Invertebrate Final

What are the categories of endangered invertebrates?

1. Extinct 2. Extinct in the wild (only survivors in captivity) 3. Critically endangered (likely to be extinct soon) 4. Endangered (risk of extinction in near future) 6. Vulnerable (risk of extinction further in the future).

What are some management approaches?

1. Identify all species through surveying, inventory, and publishing the taxonomy, natural history, and ecological roles of these organisms. 2. Identify critical areas using mapping and GIS locally, regionally, and globally. 3. Eduction and action plans using scientists to create or disseminate recovery plans with lay people assisting in education and action. 4. Create or change government policy through convincing the decision-makers.

What are the seven impediments to conservation?

1. Public: invertebrates and the ecosystem services are widely unknown to the public 2. Politics: policy makers are unaware of the importance of invertebrates 3. Science: the study of these animals is scarce and underfunded 4. Linnean shortfall: there are too many undescribed species 5. Wallacean shortfall: the distribution of the species is poorly known 6. Prestonian shortfall: the changes in space and time of these animals is unknown 7. Hutchinsonian shortfall: the natural history and habitat needs are largely unknown.

What are the particular challenges for invertebrate conservation?

1. Small macroscopic or microscopic animals 2. These creatures are least like humans often without eyes as would be expected to be found 3. Funding is often dominated by successful charismatic megafauna

What is the tardigrade reproductive system?

Almost all tardigrades are gonochoric but few are hermaphroditic species. Many are parthenogentic and males are unknown in some genera. The gonad is a single unpaired elongate sac situated above the gut and by ligaments to the dorsal body wall. It probably is a coelomic derivative. In the male, two sperm ducts exit the testis and open via a single median gonopore immediately anterior to the anus. The male reproductive system is independent of the gut. Sperm are flagellated. In females the single oviduct opens on the surface near the anus or joins the rectum which then functions as a cloaca. One or two seminal receptacles may be present.

What are the types of bryozoan zooids?

Autozooids: These ar the feeding zooids that make up the bulk of the colony. Heterozooids: these are modified, nonfeeding zooids specialized to serve a variety of other functions, typically with reduced or absent polypide and consist chiefly of the cystid. These can be attachment discs and rootlike holdfasts as well as defensive spines (Kenozooids). Avicularium: This is usually smaller than an autozooids and its polypide is greatly reduced. This is a type of heterozooid. The operculum is modified to serve as a movable jaw. These can be sessile or stalked. These are compared to bird beaks to be used for defense and cleaning of the colony.

How does a tardigrade undergo locomotion?

Contraction of the muscles achieves flexion of the body and appendages that is opposed by the hemocoel that functions as hydrostatic skeleton. Tardigrades move about slowly by crawling with their legs using their claws or discs to grasp the substratum. The first three pairs of legs are used in forward locomotion and the last pair function in retreat or grasping the substratum. The claws of the last pair are reversed to face forward in contrast with those of the first three pairs.

What is postecdysis?

Early in this stage the new cuticle consists of epicuticle and exocuticle and is soft and flexible and the animal cannot support itself. The new endocuticle is secreted and calcification and sclerotization of the skeleton take place around the water or air swollen body. Calcium is transferred from the blood to the cuticle causing blood calcium levels to drop as the cuticle is calcified. At the same time, proteins are sclerotized. As the new exoskeleton hardens, excess body water is eliminated and the soft tissues shrink away from the now oversized exoskeleton to leave room for tissue growth during intermolt. The animal remains sequestered in its retreat and doesn't feed durign the first part of this phase.

What are the types of bryozoan colonies?

Encrusting: this is the most common form in which side by side and end to end zooids are united in a two-demiensional crust or sheet one zooid thick that is attached to rocks, seaweeds, and shells. Stolonate: These resemble hydroids where feeding zooids arise from a stemlike creeping or erect stolon. The stolons have a jointed appearance that is composed of linear series of specialized tubular zooids. Fruticose: This is found with many calcified species to form erect busy colonies that resemble seaweeds. Foliaceous: These are colonies composed of a single sheet of zooids or two sheets attached back-to-back that rise leaflike above the substratum.

What are the divisions of the exoskeleton for arthropods?

Hardened cuticle is separated into sclerites (plates) that are joined together using articular membranes (soft, flexible cuticle). Muscles originated on the inner surface of one sclerite cross an intervening articular membrane and insert on another sclerite with contraction of the muscle resulting in movement of one or both sclerites relative to each other. The cuticle is typically divided into four major regions (dorsal tergite, two lateral pleurites, ventral sternite) that may or may not be sclerotized. Articular membranes connect the sclerites to form a complete ring around the segment. Each body segment has one of these four-part rings but this pattern is frequently modified by secondary fusion, subdivision, or loss of sclerites. The appendages typically articulate with the lateral pleurites. Sclerites of adjacent segments may fuse together to form a continuous sheet of rigid, sclerotized exoskeleton. Commonly the articular membrane between segments is folded beneath the anterior segment to permit expansion when the joint is extended. The appendage exoskeleton is composed of cylindrical articles connected by articular membranes to create a movable junction or articulation (joint) where the two elements are articulated.

What is the method of gas exchange for arthropods?

In small arthropods a unspecialized body surface is usually sufficient to supply adequate oxygen. Larger arthropods require more specialized structures for oxygen such as gills, book gills, book lungs, and tracheae.

What is a Christian ethics approach to conservation of invertebrates?

Invertebrates are part of God's good creation and Humans are called to "keep" and "tend" the creation. This includes permission to "use" but not "use up" (see examples in Genesis and OT, careful to not use up), many evangelicals that get this, other faiths have different approaches. There is intrinsic value of individual created beings so therefore God demands respect for his works. The covenant was with Noah and the other animals so therefore all of creation. We need to work toward redemption, as can be seen in Romans 8 where the rest of creation waits for humans to work towards second coming or new creation.

What is the Oregon forest snail, Allogona townsendiana, case study?

Management actions were taken to minimize trails and roads to avoid further habitat fragmentation. There is a push to retain stinging nettle, bigleaf maple, as these are important habitats. These organisms need us to allow fallen trees/limbs to decompose. Remediate with above elements if necessary to protect the species. Plants that were recommended for species restoration include the: Bigleaf maple, Black cottonwood, Western red cedar, Red elderberry, Indian plum, Salmonberry, Stinging nettle, and Sword fern.

How do arthropods reproduce?

Most are gonochoric and dioecious with some exceptions. Fertilization may be external or internal but is internal in all terrestrial species. There usually is mating involving some selectivity between the partners. Females usually store sperm in a seminal receptacle and later use it to fertilize the eggs. Sperm transfer can be direct but in many it is indirect and there is no direct contact between male and female gonopores, likely using spermatophores. The spermatophore is found by the female by following chemical cues and taking the entire packet or just the sperm into the gonopore, often depositing after the male has located a receptive female which may require elaborate courtship rituals.

How do tardigrades gain nutrition?

Most tardigrades feed on the cytoplasmic contents of plant cells. Soil tardigrades feed on algae and probably detritus and some are predators of nematodes and other minute soil animals including other tardigrades. The foregut and hindgut are lined with cuticle that is molted but the midgut is not. The foregut is equipped with a pair of cuticular stylets used to puncture the cells of plants or animal prey. The sharp tips of the needlelike stylets protrude into the buccal tube and are extended and withdrawn by a set of protractor and retractor muscles. The stylets are housed in stylet sheaths and braced by transverse stylet supports. that are also cuticular and extend from the stylet to the buccal tube. The stylet apparatus is homologous to a pair of head appendages and is unique to tardigrades with similar structures in herbivorous nematoides and rotifers. These species have a unique telescopic mouth cone equipped with the stylets that can be extended from the body surface along with numerous sensory structures. The stylets have salivary glands closely associated with them to secrete new stylets just before ecdysis and secrete saliva during feeding. The pharynx is a muscular pump that sucks liquid food into the gut with a Y-shaped or triradiate lumen, the most efficient configuration for radial muscles surrounding a distensible lumen. When feeding, the mouth is placed against the prey and the stylets are protruded to puncture the cell or body wall to allow for the prey contents to be sucked out by the pharynx. The midgut is secretory and absorptive as well as the side of hydrolysis and absorption. Food may be enclosed in a peritrophic membrane secreted from the midgut epithelium. The rectum receives digestive wastes, nitrogenous wastes from the Malpighian glands and is where the oviducts of females opens.

What is the development of juvenile arthropods?

Pycnogonids and many crustaceans have small eggs that hatch into larvae with three pairs of legs. These pycnogonid protonymphon larva hatches with chelicerae, pedipalps, and the first walking legs all of which are uniramous. the crustacean nauplius larva has the first antennae, second antennae, and mandibles, the latter two of which are biramous. After hatching, growth, and the addition of new segments and appendages occur only in conjunction with ecdysis. Many other arthropods exhibit direct development in which all larval stages are suppressed or occur in the egg prior to hatching and the young hatch as miniature adults with a full complement of appendages and segments.

What are Euchelicerates?

The abdomen is well developed and often segmented. The cephalothoracic segments are fused and covered by a continuous sclerite (carapace). They have lateral compound eyes. They have lost one of the two pairs of median eyes and their gonopores are on the second abdominal segment.

How do arthropods gain nutrition?

The arthropod gut consists of three regions . The foregut is responsible for ingestion, storage, and the initial processing of food prior to chemical digestion or prior to ingestion. The midgut functions in enzyme secretion, hydrolysis, and absorption of the digestive ceca, to increase the surface area for absorption and intracellular digestion. The ceca may be extremely large and occupy much of the hemocoel. The hindgut is responsible for feces formation, feces storage, and the reclamation of valuable materials. It sometimes has a respiratory role. The foregut typically includes a pharynx, esophagus, crop, and proventriculus. Its epithelium often secretes elaborate, sclerotized, cuticular structures such as teeth and setae. The midgut has at least one pair of digestive ceca. A valve separates the foregut from the midgut and another lies between the midgut and the hindgut. The epithelium in the vicinity of the foregut-midgut valve secretes a thin, permeable, peritrophic membrane around the food mass to protect the delicate midgut walls from abrasion by the food and plays and important role in localizing digestive enzymes. The digestive tract has additional accessory organs with mouth parts that are modified appendages.

What is the structure of the body wall of onychophora?

The body is covered by a thin chitinous cuticle or exoskeleton. The cuticle is flexible and permeable, composed of α-chitin and protein with a thin epicuticle underlaid by a procuticle with an exocuticle and endocuticle. The exocuticle and outer epicuticle layer contains tanned proteins. The cuticle is molted frequently (sometimes as much as eery two weeks during lifespan of six years). The cuticle has no sclerotized plates and is flexible to allow it to squeeze into small crevices. The cuticle is secreted by a monolayer of epidermis. Muscles join the cuticle using tonofilaments transversing epidermis. Pigment granules of a variety of color are found in the epidermal cells. The papillae and scales give the body a velvety and iridescent appearance. There is a thick layer of connective tissue below the epidermis with layers of collagen fibers in either a parallel or perpendicular to the long axis of the body.

What is the characteristic chelicerata form?

The body is divided into a cephalothorax and an abdomen. The cephalothorax consists of the acron plus seven segments and bears six pairs of appendages. It forms in the embryo through fusion of the ad and the thorax. The appendages of the first cephalothoracic segment have been lost. There are no antenna present. The first appendages on the chelicerate cephalothorax are a pair of prehensile chelicerae on the second cephalothoracic segment. Each chelicera consists of two or three articles, the distal two of which form a chela or pincer. The second appendages are pedipalps modified to perform various but often sensory functions in the different taxa. The remaining cephalothoracic appendages are four pairs of walking legs. Primitively the head bears four median pigment-cup ocelli and two lateral compound eyes. The remaining trunk segments constitute the abdomen or opisthosoma consisting of 12 or fewer segments. Abdominal appendages, when present, are primitively platelike and have a respiratory function. The abdomen of derived chelicerates usually have highly modified appendages on some segments or lacks appendages. Primitively the abdomen is divided into an anterior preabdomen of seven segments and a posterior postabomen with five segments and a terminal telson or spike. This original pattern has been variously modified in the many chelicerate taxa. The gonopores have moved anteriorly to the second abdominal segment.

What does the body cavity of a tardigrade look like?

The gonads appear to be derived from a coelomic space while the chief body cavity is an expanded connective tissue compartment or hemocoel. It is filled with colorless blood containing hemocytes. Much of the hemocoel is occupied by these nutrient storage and phagocytic cells which may be attached or float freely. There is no heart and movements of the body adn appendages circulate the blood through the hemocoel. tissues in or adjoining the hemocoel are separated from it by their basal laminae.

What are the characteristics of the onychophora gut?

The gut consists of a foregut, midgut, and hindgut. The foregut includes the pharynx and esophagus and is lined with an epidermal epithelium and its cuticle. The mouth opens into the muscular pumping pharynx. The pharynx pumps partially predigested liquid food through the esophagus into the midgut. The long midgut or intestine extends most of the length of the animal and its gastrodermis is absorptive and secretory. As an endodermal derivative, it is not lined with cuticle. A peritrophic membrane similar is secreted around the food mass as it enters the midgut to protect the midgut from abrasion. The hindgut is the rectum and is ectodermal lined with a cuticle. The rectum opens to the exterior via the anus on the ventral surface near the posterior end of the animal.

How do arthropods fit within protostomes?

The larval stage resembles annelids and some mollusks. These have metamerism, 1 pair of appendages per segment like that of annelids. These have hemocoel like that of mollusks. The insect or crustacean compound eye is also found on certain bivalves and some polychaetes. The metamerism and jointed is also found in onychophorans. The molting is also seen in nematodes and other ecdysozoa.

What is the structure of the hemocoel in onychophora?

The longitudinal muscles border the hemocoel. The reduced coelom is is represented by nephridial sacs and gonads. The gut, slime glands, salivary glands, heart, saccate nephridia, reproductive system, and nervous system are immersed in the body of the hemocoel.

How do onychophora move?

The onychophora hold their body above the substratum and crawl slowly using their legs in combination with extension and contraction of the body. Body length is controlled by the circular and longitudinal body-wall muscles acting in conjunction with the hemocoel. When a segment is extended by contracting the circular muscles, both of that segment's lift off the ground and move forward in a recovery stroke. The effective stroke is accomplished by shortening the segment by contracting the longitudinal muscles. The effective strokes of the two legs of a segment do no alternate as they do in most crawling arthropods.

What is the arthropoda body wall?

The outermost layer of the body wall is the nonliving, secreted cuticle composed of α-chitin and protein. collagen, abundant in the cuticle of annelids, is absent from that of arthropods. The living components of the body wall are reduced and simple. Strength and protection is provided by the exoskeleton and therefore there is little connective tissue other than the blood. The continuous sheets of unspecialized circular and longitudinal muscles characteristic of annelids has been replaced by specialized muscles that connect adjacent regions of the exoskeleton or extend into appendages. The cuticle is secreted by the ectodermal epidermis lying immediately below it. The epidermis is a monolayered epithelium that secretes and is underlaid by the basal lamina or a more elaborate basement membrane of protein fibers and ground substance that surrounds and contains the musculature, hemocoel, and viscera. The body cavity of arthropods is a large space in the connective tissue compartment derived from the blastocoel of the embryo. It is a hemocoel not a coelom filled with hemolymph (blood) that is lined by the basal laminae of the gut and epidermis.

What is the asexual reproduction for cycliophora?

The pandora larva produced by stem cells exits the adult and crawls about using a ventral ciliary field to attach and develop into a new feeding-stage adult on the original lobster.

What is the sexual reproduction for cycliophora?

The stem cells produce male or female larva. The prometheus male is an immature male which produces cells that become a functional male. The female produces only one oocyte that is fertilize by the male that is still attached to the larger feeding stage. This allows movement to a new lobster.

How is molting controlled?

The steroid hormone ecdysone targets the epidermal cells that secrete the cuticle and controls the molting process in all arthropods. It is secreted by endocrine glands (prothoracic glands in insects, Y-organ in crustaceans) and is distributed to the epidermis by the blood. The synthesis and release of this hormone is regulated by neurohormones from sources that vary with taxa. In insects the brain hormone goes to the prothoracic gland to release the ecdysteroid hormone causing the molt. In crustaceans the X-organ releases an inhibitory hormone preventing ecdysis but in the absence of the X-hormone the Y-organ secretes ecdysone causing molting.

What is the structure of the tardigrade body wall?

The thin body wall consists of only two layers. The outermost cellular layer is the epidermis known as eutelic (composed of a constant and genetically determined number of cells). Many tardigrade tissues are eutelic, also seen in small-bodied gnathiferan and cycloneuralian taxa. Tardigrades lack motile cilia. The epidermis secretes a cuticle composed of four layers (epicuticle, exocuticle, mesocuticle, endocuticle) made up of chitin, tanned, and untanned glycoproteins, mucopolysaccharides, polysaccharides, lipids, and lipoproteins. Some species (armoured) have articulated sclerites in the dorsal cuticle. The cuticle often contains spines, granules, pores, or other sculptures. The exoskeleton which includes the cuticular claws and stylets as well as lining the fore and hindguts is molted periodically where the body contracts and pulls away from the old cuticle that is then slipped off and left behind as a relatively intact exuvium. The cuticle of the body and gut is secreted by the epidermis but stylets and chitinous supports are secreted by the salivary glands. The stylets are often calcified with new claws secreted by ectodermal claw glands.

What are the dominant phyla of invertebrates?

The top ten are: arthropods, molluscs, nematodes, platyhelminthes, annelids, cnidarians, porifera, echinoderms, bryozoan, and rotifers.

What are hexapods?

The trunk of these animals is divided into thorax and abdomen. Adults and usually immatures have three pairs of legs while the adults of most taxa have two pairs of wings. Wings are not found on primitive hexapods. The legs and wings are always present on the thorax. Only one pair of antennae is present. A tracheal system provides for gas exchange, the gonoducts open at the posterior end of the abdomen, and Malpighian tubules are the excretory organs. Armoured cuticles provide protecting from predators, pathogens, and desiccation as well as attachment sites for skeletal muscles. Adaptations for water conservation include the tracheae, Malpighian tubules, and waterproof cuticle and eggshell to all these animals to be well adapted for terrestrial environments.

What is the pre-history scope of the problem on extinction?

There is climate change and humans use of fire and introduction of disease through migrations.

What are the characteristics of the arthropoda phylum?

These animals include segmented animals with exoskeletons and jointed appendages. These account for 80% of all known species with an ability to survive virtually every environment with presence in marine, terrestrial, freshwater, and aerial habitats. They are easily the most successful colonizers of terrestrial habitats. These are protostome bilaterians that are triploblastic and metameric. New molecular biology evidence suggests a more distant relationship to nematodes and cycloneuralians. These species have segmented body, chitinous exoskeleton with ecdysis, jointed and paired segmental appendages, and the absence of locomotory cilia. These species have a ventral nerve chord and well-developed eyes.

How do Onychophora get nutrition?

These animals prey on small arthropods using jets of slime excreting from the slime glands of the oral papillae extending up to 15 cm from the animal to entangle the animal. The slime undergoes denaturation by exposure to air causing the stickiness to be lost after a few minutes. The slime does not stick to the hydrophobic cuticle of the Onychophoran itself.

What are cycliophora?

These are a phylum also known as small wheel bearers with one species (Symbion pandora, discovered in 1995). This is commensal or parasitic on lobster mouthparts. These have a buccal funnel (inverted bell with mouth at large open anterior end surrounded by ring of multiciliated epithelium to created downstream suspension-feeding system), adhesive disc (large ovoid trunk joined to this, attaches individual to the host), and internal buds for new feeding parts (produces new buccal funnel and gut for existing feeding-stage individual, no new organism). The nervous system is poorly understood.

What are urochordata?

These are a phylum of chordata known as the tunicates that make up 90% of chordates. These are found throughout the ocean as well as polluted and estuarine waters as sessile and attached with the body attached and covered to the substratum by a complex tunic. Many are colonial. With the exception of Appendicularia, the main chordate characteristics are only found in the larval stage. These use filter-feeding and bear tunics all using pharyngeal baskets or bars with an endostyle that produces mucus. The brain is improved in larvaceans and thaliaceans.

Are lophophorates deuterostome or protostome?

These have a trochophore larvae most of the time which is found in proteosomes. The eucoelomate with radial and indeterminate cleavage makes them deuterostome. Molecular data indicates a protostome connection but the developmental data indicates a deuterostome link.

What are the characteristics of the onychophora phylum?

These are also known as velvet worms. These are terrestrial, wormlike bilaterians with strong morphological similarities to arthropods and annelids. The 110 described species are found in the tropics and temperate southern hemisphere. These are nocturnal, negatively phototactic, and found in humid and usually dark habitats. They often live in rain forests in leaf litter or under objects on the forest floor but will move into the soil to become dormant in unfavorable environmental conditions.

What is the reproductive system of onychophora?

These are always gonochoric and sexually dimorphic with males being smaller than females. The gonads are paired coelomic derivatives connect by gonoducts to an unpaired gonopore on the posterior ventral surface.

What are setae for arthropods?

These are articulated chitinous projections of the exoskeleton secreted by a trichogen cell in the epidermis. Setae are hairlike usually flexible, solid, or hollow bristles. their morphological and functional variety is almost limitless. The external sensory receptors usually involve modified setae. Branched, plumose setae are used to increase the surface area of swimming appendages and as filters to extract food particles from water. Dense, feltlike coverings of very fine setae are used in aquatic insects to trap and hold air while the insect is submerged. Heavy, inflexible setae are spines.

What is the form of tardigrades?

These are bilaterally symmetrical bodies that appear plump and cylindrical. These appear to be composed of five segments superficially including a short heat of one segment and a trunk with four segments. The head may actually consist of three segments while the trunk consists of four or five internally, as transverse cuticle folds are misleading and do not correspond to actual segments. Each trunk segment has a pair of short stubby legs. The tip of each leg has four to eight retractile claws or adhesive discs. The legs, like those of the onychophorans, are lobopods. Each leg has weakly separated regions that are sometimes designated as coxa and femur. short, intrinsic muscles are located inside the legs. The legs of many marine species are capable of telescoping.

What are the digestion characteristics of echinodermata?

These are carnivores (sea stars), herbivores (sea urchins), deposit feeders (sea cucumbers), and filter feeders (sea cucumbers and brittle stars).

What are arthropod book gills?

These are characteristic of horseshoe crabs that are flat, pagelike lamellae extending from the ventral surface of the abdomen.

What is the hemichordata phylogenetic relationship?

These are clearly deuterostomes. These undergo radial cleavage and show a molecular data relationship to echinoderms. These have the gill slits, nerve cord, stomochord support rod (rudimentary notochord), and molecular data linking them to chordates. Some molecular data also links these to lophophorates.

What are diplopoda?

These are commonly known as millipedes, with no one species having any more than 710 legs and most having fewer. These are secretive, nocturnal detritivores that subsist on decaying vegetation. Negatively phototactic, they avoid light and live beneath leaves, stones, bark, and logs. Millipedes are common in soil and leaf litter and many are cave dwellers. They vary from 2 mm to almost 30 cm in length.

What is the structure of the arthropod paired, jointed, segmental appendages?

These are composed of a linear series of articles each being a cylinder of hardened exoskeleton that joins or articulates with the body or with another article. Successive articles are connected by flexible cuticle that permits movement of the articles with respect to each other. Flexor and extensor muscles inside the cylinders that extend across the flexible articulations contract to produce movement. The head appendages tend to be specialized for sensory reception or feeding while the thoracic and abdominal appendages might be adapted for locomotion, reproduction, respiration, food manipulation, and other functions. Appendages can be lost from some regions (particularly the abdomen). The appendages of many arthropods have a single branch or ramus (uniramus, hexapods, myriapods, arachnids) while others have two major branches (biramous, crustaceans, trilobites).

What are the reproduction and development characteristics of echinodermata?

These are dioecious with external fertilization. Some species brood their young such as the six-rayed star. There is a radial cleavage pattern of development. The larval stages are bilaterally symmetrical. The pluteus larva are found in urchins and brittle stars. The brachiolaria larva is found in sea stars, the bipinnaria or auricularia larva is found in sea stars and sea cucumbers. The doliolaria is found only in crinoids. Asexual reproduction requires a fifth or more of the central disc to allow it to occur.

What are nephrocytes?

These are excretory cells common in the arthropods that are large pinocytic cells in the hemocoel that process wastes and toxins that the nephridia or Malpighian tubules are unable to eliminate. These may metabolize the waste and return it to the hemocoel in a form that can be eliminated by the principal kidneys or they may function as storage kidneys and sequester it indefinitely.

What are arthropod tracheae?

These are found in arachnids, onychophorans, and tracheates. These tubular invaginations of the epidermis and cuticle extend inward from an opening, the spiracle, on the body surface. These branch into ever-smaller tubes ultimately delivering oxygen directly to individual cells without the mediation of the hemal system in most cases.

What are Malpighian tubules?

These are found in terrestrial arthropods for excretion. This tends to be the principal or sometimes only excretory organ for insects and arachnids. These excrete nitrogen in the form of insoluble uric acid or guanine. These are blind-ended tubular diverticula of the gut located at or near the midgut-hindgut junction. These extend into the hemocoel to be bathed in blood.

What are arthropod campaniform organs?

These are highly modified sensilla in which the seta forms a cuticular dome to which a sensory dendrite is attached. The dendrite is sensitive to deformation of the dome. In cockroaches this is responsible for the inhibition and excitation of the righting response.

What are mechanoreceptors for arthropods?

These are hollow seta with one or more sensory neurons inside. Deflection of the seta from its resting position affects the polarity of the neuronal membrane and the brain is informed of the disturbance. The amount of pressure required to deflect the seta and activate teh neuron is related to the size of the seta. Fine setae detect gentle pressures such as weak air currents and robust setae respond to heavy pressures.

What are saccate nephridia?

These are known as a number of different names such as end sac organs, sacculi, coxal glands, green glands, antennal glands, and amaxillary glands. These are found in aquatic arthropods as well as many terrestrial chelicerates and few terrestrial tracheates. These are filtration kidneys consisting of a tubule draining into the end sac. The nephridium is surrounded by blood which is pressurized by the heart. The walls of the end sac have basal lamina and podocytes that form the filter. The ultrafiltrate or primary urine forms in the end sacs. The tubule connects the end sac with a nephridiopore on the exterior where valuable resources are removed from the ultrafiltrate until exit from the nephridiopore.

What are the structures of the onychophora leg?

These are known as lobopods. These have internal musculature that can bend at any position along their length, ending with a sclerotized claws that have a set of spiny pads at the base of the claws to contact the substratum (lobopods). Males tend to have fewer legs than females. Each lobopod has numerous sensory papillae. On each leg is a coxal organ on the ventral surface of its base that are eversible to be used to gather water from the substratum. Some species have crural glands at the base of some legs that open via the crural papillae.

What is decapoda?

These are large, abundant, and ecologically and economically imporant species. Most are marine and benthic but crayfish and some shrimps and crabs have invaded freshwater. Few crabs are terrestrial and some are planktonic. The head often has anterior, median, immovable rostrum with both pairs of antennae being biramous. The appendages of the first three fused segments are maxillipeds that function as mouthparts. The remaining five pairs of thoracic appendages are the ten pereopods from which the name decapoda is derived. The first pair is frequently enlarged and chelate to form a prehensile cheliped or pincer in which the last two articles form opposable fingers (one is movable and closes against the other). The pereopods are usually stenopodous walking legs although some may be chelate. Decapod pereopods usually lack exopods and are uniramous but typically bear epipods modified as gills. The carapace is fused dorsally with all eight thoracic segments.

What are the Onychophora slime glands?

These are large, branched organs found in the middle region of the hemocoel. Each of the two glands connects to the pores on the oral papillae by a thick duct that serves as a reservoir for undischarged slime. The slime glands are modified crural glands of the segment of the oral papillae.

What are important secretory glands or cells of the arthropod cuticle?

These are located in the epidermis or may be insunk below the basal lamina into the connective tissue compartment. These connect with the surface via long ducts that traverse the exoskeleton. Tegumentary glands may be unicellular or multicellular. they are thought to secrete an enzyme that promotes tanning and are abundant in sclerotized areas of the cuticle. Some tegumentary glands may have other as yet unknown functions. Trichogen cells secrete setae whereas tormogen cells create the flexible sockets for the setae.

What are arthropod book lungs?

These are present in many arachnids. This is an invaginated pocket of the exoskeleton that contains numerous secondary evaginations. The evaginations are flat, leaflike lamellae whose function is to increase surface area for exchange. Oxygen transport from the lungs to the tissues is through the blood.

What is the relationship of kamptozoa to lophophorates?

These are protostomes with spiralian cleavage. There is also possible cycliophoran relatives.

What are arthropod exoreceptors?

These are receptors for light, taste, smell, equilibrium, touch virbrations, and pressure. These penetrate the exoskeleton as well as modify it to allow it to become part of the sensory system. These are sensilla consisting of modified regions of the cuticle associated with a derived cilium, sensory neurons, and support cells. Each is specialized structurally to respond to a specific stimulus.

What are amphipoda?

These are small crustaceans found in large numbers and high diversity in aquatic habitats. Most are marine but many are found in freshwater and one family has terrestrial and semiterrestrial species. These are flattened horizontally. These are often described as being unstable, as they will tip over if not in water. This contains beach hoppers that breakdown seaweed and act as food for other animals. This includes Orchestia and Caprella (skeleton shrimp, marine benthic, cling to complex substrata, consume diatoms)

What are arthropod ocelli?

These are small, nonimage forming, and useful only in detecting the source of light but some are large with abundant retinal cells to form images (spiders). The lens is a thickened area of the cuticle and the retina and pigmented layer is derived from the epidermis. These are referred to as median eyes.

What are serial homologs?

These are structures arising from the equivalent embryonic primorida of different segments but share in a similar pattern of morphogenesis. This is within a single individual. Homonomy is when all segments and their appendages were similar or identical in structure, function, and position. Heteronomy is when modifications as a result of natural selection have resulted in segments and appendages specialized for many different functions.

What are the arthropoda acron and telson?

These are the anterior and posterior end of the arthropod body respectively. These are not serially homologous to the segments that lie between them. The first true segment bears the mouth and is immediately posterior to the acron (preoral). The telson is postanal. Growth results from new segments arising from mitotically active teloblast regions anterior to the telson. Segments anterior to the telson are progressively older and the youngest is adjacent to the telson. The acron and telson are present in larva and don't arise from teloblasts.

What are chilopoda?

These are the centipedes that have between 15 to 191 pairs of legs but always has an odd number of pairs. These are distributed throughout the world in both temperate and tropical regions from sea level to high elevations in soil and humus, beneath stones, bark, logs, in caves, and mosses. Most are nocturnal while some are intertidal. These are poison-fanged raptors and some of the larger species will bite humans.

What is stomatopoda?

These are the mantis shrimps that are predators of fish, crabs, shrimps, and molluscs with many distinctive features for their raptorial behaviour. The raptorial claw used to capture prey is extended rapidly and has long spines or is shaped like the blade of a knife on the inner edge of the distal article. These have the best developed compound eyes of any crustacean, capable of detecting moving objects and depth perception.

What are chaetognatha?

These are the marine arrow worm phylum that is somewhat deuterostome and protostome like. The development has radial and spiral cleavage, coelom, and three body parts. The head cuticle is periodically shedding spines in a molt like fashion. There is a ventral nerve cord. Molecular data points to a possible ecdysozoa connection. These are less than 15 cm with fins, a spiny head, trunk, and tail. These are fish-like predators with teeth, spines, and eyes making them brainy. These tend to lie-in-wait with vertical migration and neurotoxins. They are mainly swim head first like an arrow shot from a bow followed by a slow decent head first to detect the swimming vibrations of their prey (mostly small crustaceans and planktonic animals).

What are anomura?

These are the strange tail crabs, containing crayfish, lobsters and burrowing shrimps that include Pagurus (hermit crabs, use discarded snail shells), Lithodes (king crab), Petrolisthes (porcelain crab, common shallow-water decapod, swim by flapping abdomen), and Upogebia (mud shrimp, shallow water or intertidal, long, deep burrows). These are benthic animals adapted for crawling with a body that is dorsoventrally flattened. The legs are usually heavier than those of shrimps and typically the first pair are powerful chelipeds. The pleopods are not adapted for swimming.

What are brachyura?

These are the true crabs that include Cancer (used as food, Dungeness or market crab), Hemigrapsus (shore crabs), Pinnixa (pea crab, lives within bivalve shell), and Uca (fiddler crab, related to ghost crabs, found along sea beaches and brackish inter-tidal mud flats, lagoons and swamps). These have the most highly specialized body form found in moth benthic marine habitats.

What are Caridea?

These are the true shrimps with a cylindrical or laterally compressed body with a well-developed muscular abdomen. Most shrimps are bottom dwellers that use pereopods for crawling sometimes using for intermittent swimming. These live among algae and sea grasses, beneath stones and shells, and within holes and crevices in coral and rock. Crangon (peraeids and sand shrimp_ are shallow burrowers in fot bottoms and use the beating pleopods for digging with activity patterns coordinated with light or tidal cycles. There is also the Pandalus shrimp in this order.

What are euphausiacea?

These are the whale shrimp or krill and are pelagic crustaceans with a shrimplike body with a highly developed carapace fused with all thoracic segments. These swim using the large, setose pleopods. These are suspension feeders of zooplankton but many consume phytoplankton. Most are bioluminescent and the body is speckled with 10 eyelike photophores located on the coxae, eyestalks, and abdominal sternites consisting of lens, pigment cup, reflector, and mass of cells that produces light. Luminescence is probably an adaptation for schooling and courtship. These tend to have cosmopolitan distributions with about two thirds occurring in all oceans. These are the chief food of many marine animals and a blue wale may consume a ton of these at just one of up to four feedings each day. Some may molt very rapidly and many will literally jump out of their skins to function as decoys to foil sight-orienting predators.

What are the characteristics of the tardigrada phylum?

These are tiny metazoans known as water bears or slow walkers. They have typical body length of 100 to 150 µm but can be up to 1.5 mm. There are common in a variety of habitats including marine, freshwater and intermittently moist terrestrial habitats. These show similarities to cycloneuralians and arthropods, being closest to arthropods. If found in terrestrial environments such as mosses, lichens, leaf litter, and soil, these individuals are only active when a film of water covers them, without this they are in a state known as cryptobiosis.

What are the body plan characteristics of echinodermata?

These are triploblastic, unsegmented, tube-in-tube structure that has pentamerous radial or biradial symmetry in adults. There are no heads but some have arms. These can be divided into aboral and oral surfaces.

What are arthropod arteries?

These are tubular extensions from the heart that open into the hemocoel. The largest are sometimes referred to as aorta. The principal arteries are the anterior aorta, paired segmental arteries, and in some taxa, a posterior aorta. In derived arthropods the number of pairs is less than the number of segments and the arteries are no longer segmental.

What are arthropod equilibrium receptors?

These are used in the detection of gravity, balance, and acceleration. These are found only in malacostracan crustaceans. This is similar to a statocyst for the detection of a gravitational field.

What is the female reproductive system of onychophora?

These consist of paired ovaries coalesced along the midline and attached to the horizontal diaphragm. The paired female gonoducts connect the ovary with the single gonopore located on the posterior ventral midline. Each gonoduct is differentiated into a proximal oviduct and distal uterus in viviparous species. The uteri join to form a single vagina that connects with the gonopore. Eggs are gestated in the uteri which may contain many embryos simultaneously. In females of oviparous species, there is a seminal receptacle for the storage of sperm and the gonopore opens at the end of a large ovipositor.

What are arthropod chemoreceptors?

These detect chemicals from distant or contact sources. These require a thin, permeable or perforated cuticle that permits passage of the chemical to the membrane of a chemosensory neuron. A reaction between the stimulus molecule and specific receptor proteins on the neuronal membrane affects the membrane potential and sends a signal to the brain. Chemoreceptive sensilla are modified hollow setae with substrate-specific chemosensory neurons inside. There may also be more elaborate chemosensory peg organs with numerous sensory neurons.

What are the crustacea characteristics?

These have a crust or carapace that is often hardened with calcium carbonate. There are two pairs of antennae along with other anterior appendages. These species have three or four simple pigment-cup ocelli grouped to form a median naupliar eye. The legs are biramous with endopodite (used for walking) and exopodite (used to create currents and swimming, leaf like) that readily autonomize that are regenerated in one to two molts. These have a characteristic triangular nauplius larval form. These contain chromatophores in their cuticle and can also undergo color change in some species. These contain a maximum of two pairs of saccate nephridia (second antenna segment, second maxilla segment).

What are enteropneusta?

This is a class of hemichordates known as the gut breathers. These are large, solitary acorn worms with a U-shaped burrow in mud or sand. Some produce phosphorescent slime. These leave in shallow water but some occur in the deep in and in association with hydrothermal vents.

What are the movement and support characteristics of echinodermata?

These have an endoskeleton (internal skeleton) known as the test in urchins that contains calcareous ossicles that are articulating or sutured while bearing spine. The ossicles are located in connective tissue dermis to provide skeletal support. There is also the important water vascular system which is a series of fluid-filled canals that goes from the madreporite, stone canal, ring canal, radial canal, ampullae, and finally the tube feet or podia. The polian vesicle is additional water storage for the water vascular system. The tube feet adhere through suction and duo-glands (double glands for grabbing and releasing).

What are mandibulata?

These have antennae on the first head segment, a three part brain with a deutocerebrum, mandibles on the third head segment, and maxillae on the fourth.

What are the respiration and circulation characteristics of echinodermata?

These have gills, podia, and an extensive coelom. These animals can use tube feet for the gill surface. The coelomocytes are the white blood cells used for phagocytosis and oxygen transport. The hemal system uses the perivisceral coelom for nutrient transport possibly.

What are apposition eyes?

These have no cone ctalk and the cone cells are close the the rhabdome. Both screening pigments are maximally dispersed in their cells so the ommatidium is isolated optically from adjacent ommatidia by the resulting curtain of dark pigment. Light entering a given cornea is confined by the screening pigment to one ommatidium, stimulates the rhabdome of that ommatidium and cannot escape to stimulate the rhabdomes of adjacent ommatidia. These eyes function well in bright light and permits the greatest resolution of the image.

What are the inarticulata?

These have no processes with a complete gut. This has a hinge with valves held together only by muscles and connective tissue but no hinge teeth or sockets. Valves are closed by direct muscular action, opened by hydrostatic coelomic pressure. Valve musculature is complete. There is no brachidia from the dorsal valve to support the lophophore. Development is direct with larva resembles a tiny adult.

What is the onychophora form?

These have numerous paired segmental appendages. They are soft bodied and the skin is dry and velvety smooth to the touch. Most are 5 mm to 15 cm with a body that is more or less cylindrical in cross section, although flattened ventrally and coated with numerous large and small papillae. There is no external signs of segmentation other than the segmental spacing of the appendages with serial repetitions of ostia, nephridia, and ganglia internally. The body bears 13 to 43 pairs of segmental trunk appendages with all trunk appendages being similar, uniramous, stubby, fleshy legs. The head contains annulated sensory antennae as well as sharp sclerotized and claw-like mandibles to lacerate the prey. The oral papillae open onto a pair of slime glands (modified crural glands) that ejects milky-white slime to be used to entangle prey and predator.

What are the muscle layers of the onychophora body wall?

These have smooth and unspecialized body wall muscles inside the connective tissue. The outermost layer of circular muscle is adjacent to the connective tissue. The innermost layer consists of longitudinal fibers. There is a thinner sheet of oblique muscles in the middle. The dorsoventral muscles divide the hemocoel into compartments (two lateral and one median). These body wall muscles are used to move the legs.

How do arthropod muscles attach to the cuticle?

These have tendons that join muscle fibers ending in the epidermis to the cuticle. The tendons are composed of a patch of specialized epidermal cells and their secreted fibers. The fibers are two sequential bundles of tension-bearing protein strands spliced together end-to-end. One bundle, composed of intracellular microtubules, spans the tendonal cells and links them to the muscle myofilaments by desomosomes. The seond bund of extracellular tonofilaments is secreted from the apex of the tendonal cells and attaches them to the cuticle. The tonofilaments are not hydrolyzed during the molting process and the connection between the muscle and the exoskeleton is maintained thorughout ecdysis.

What are parasitic crustaceans?

These include sacculine (barnacle parasitic to crab, creates robot crab that attacks the thoracic ganglion) and Salminocola (copepod parasitic on salmon).

What are the taxa of arthropoda?

These include the Chelicerata, Mandibulata (crustacea and tracheata, appendages for feeding known as mandibles), and Trilobitomorpha (extinct).

What is the monarch butterfly, Danaus plexippus, case study?

These organisms require milkweed for their life cycle with a migration pattern from North America to Central America. Planting of milkweed and restoring native plants will help in the species management.

What is the propertiius duskywing, Erynnis propertius, case study?

These require Garry oak Quercus garryana meadows. These are present on TWU Crow's Nest Ecological Research Area on Salt Spring Island.

What are the characteristics shared by phylum tardigrada and phylum onychophora?

These share arthropod characteristics that include a chitinous cuticle that is molted, striated muscles, and a molecular relationship. These two phylum also share non-arthropod characteristics included lobopods (unjointed appendages), and annelid-type segmentation as well as other annelid characteristics.

What are the characteristics of panarthropoda?

These species are segmented and have paired segmented appendages. The exoskeleton is secreted that must be molted (ecdysis) to permit growth. This includes phylum tardigrada, onychophora, and arthropoda.

What is the arthropod nervous system?

These species central nervous system consists of a dorsal supraesophageal ganglion or brain in the head, a pair of circumenteric connectives that encircle the gut just posterior to the brain, and a paired, ventral, longitudinal nerve cord with paired segmental ganglia, and segmental sensory and motor nerves. This central nervous system also has a ventral double nerve cord. There is also a peripheral nervous system that takes sensory and motor neurons in the nerves to carry sensory information to the central nervous system and motor commands back. This nervous system is capable of a high firing rate.

What are crustacea?

This is a subphylum of Mandibulata. that includes the shrimps, crayfish, lobsters, and woodlice. This is a chiefy aquatic taxa with a few that have colonized terrestrial environments but are not as well adapted to this lifestyle as arachnids and tracheates. Most are free-living and can be swimming, crawling, burrowing, or living between sand grains.

What are arthropod muscles, especially with their importance in flight?

These species have a complex array of small, individual, specialized flexor and extensor muscles attached to the exoskeleton. These muscles are cross-striated and originate and insert on adjacent sclerites of the body or appendages. Contraction of the muscle results in movement, either flexion or extension, of one sclerite or article with respect to another. These muscles use alternating power and recovery strokes for flying in rapid movements.

What is the arthropod excretion system?

These species have green glands or coxal glands that are used for water and nitrogen balance. Ion uptake and expulsion occurs at the gills.

What are the characteristics of arthropoda segmentation?

These species have linear series of segments. There is a tendency in some arthropods to reduce or eliminate the outward signs of segmentation. Typically the exoskeleton is divided into hardened segmental rings that are clearly visible externally. Successive rings are separated by flexible areas and the pairs of appendages are attached in obvious correspondence with the segments. Internally the systems have segmentally repeated components. There can be a tendency for adjacent skeletal rings to fuse together causing loss of internal and external segmentation characteristics in derived arthropods.

What are the specifics of tardigrade development?

These species undergo holoblastic cleavage and equal but neither spiral nor radial. Development in direct with juveniles resembling adults and therefore no real larval stage. The blastocoel is indistinct or absent and the hemocoel develops as a new cavity in the connective-tissue compartment. The gonad develops from a coelomic space. First instar tardigrades have a mouth but no other openings. Second instars have a mouth and anus and third instars have a mouth, anus, and gonopore. Development in completed within 14 days or less and little bears hatch by breaking the eggshell with their stylets. Tardigrades are eutelic and further growth is achieved by increasing the size of cells rather than by adding new cells. As many as 12 molts may take place over the lifetime of a tardigrade which has been estimated to be 3-30 months with frequent periods of cyptobiosis lengthening this to decades or more.

What are biramous appendages?

These typically begin with a proximal protopod that is often divided into two articles (coxa and basis). From the basis are the two rami consisting of a lateral exopod and medial endopod. There may be other branches in addition to the endo- and exopod. The uniramous appendages of the modern chelicerates and tracheates probably arose from this ancestral pattern through loss of the exopod.

What is onychophoran development?

These undergo superficial (shared with arthropods) or total cleavage. The type of cleavage depends on the amount of yolk in the egg but there is no spiral cleavage. Viviparous species have developing embryos retained in the uterus and the adult gives birth to juveniles with a gestation period that may be a year or more with developing embryos that may be of different or same age. In matrotrophic, viviparous taxa eggs are usually tiny, yolk-less, and nourished in utero by secretions of the uterine epithelium causing holoblastic cleavage. There may be a tissue connection or placenta present between the uterine epithelium and embryo for transport of these secretions. Without a placenta secretions are released into the uterine lumen and absorbed by the embryo. Lecithotrophic viviparous species retain the embryos in utero but are nourished by the moderate amounts of yolk present in the egg to undergo superficial cleavage. Oviparous species have large yolky eggs enclosed in a chitinous eggshell undergoing superficial cleavage. Development for these species occurs outside the mother's body without maternal care.

What are the offense and defense characteristics of echinodermata?

These use autonomy (the ability to drop body parts, sea cucumbers and brittle stars, local softening of connective tissue causing the affected region to loosen and detach) as well as catch tissue (connective tissue goes from soft to hard). The appendages have spines, some of which are venomous. The pedicellariae are valved jaws that can also be venomous.

What are the nervous coordination characteristics of echinodermata?

These use circumoral rings and radial nerves but no real brain is found. There is a diffuse nerve network using ectoneural (sensory from epidermis), hyponeural (motor function of brittle stars), and entoneural (only in crinoids) networks. There are eyespots and lenses on the ray tips or chromatophores in brittle stars (entire central disk has multiple light sensing capabilities on the aboral surface).

Why are humans the entire problem of extinction?

They were the cause of the fall and the curse. Technology is also a problem as the geometric population increases so too does the need for food (hunting/gathering), space (habitat destruction), and energy (pollution, pesticides, climate change). It is possible the only survivors will be mosquitoes and cockroaches.

What are larvacea?

This class urochordates is also known as appendicularia or larval. These are planktonic mobile tunicates that build houses for food capture. These can build up to 15 houses of mucus and abandoned them per day. Water is filtered through the house by pumping water with its tail. A common species is Oikopleura (tail flexed anteriorly and projects forward in front of mouth). These are filter feeders.

What are cladistics?

This creates 25 major taxa based on molecular data. This results in rapid change as new data produced on genomes of various species becomes available.

What are trilobitomorpha?

This is a subphylum of arthropoda found only in fossils. The closest living relatives are probably the chelicerates. The commonality of these fossils allows for identification and arrangement of sedimentary rock strata into proper geological sequence. These species had a three part body (cephalon, thorax, and pygidium).

What is the arthropod exoskeleton?

This cuticle is responsible for protecting surfaces from abrasion, from attack by pathogens, for structural support, and for maintaining body shape. This can be a rigid skeleton that mediates the interactions of antagonistic muscles or can be soft, flexible, and hingelike. This exoskeleton must be shed or molted for the animal to increase in size or add segments and appendages. This cuticle is secreted wherever there is epidermis and covers the entire outer surface of the body as well as many surfaces that extend deep into the body (foregut, hindgut, book lungs, trachea). The cuticle is naturally soft and flexible until it is hardened via sclerotization (chemical reactions using tannings that harden, strengthen, and darken cuticle by forming covalent cross-links between protein molecules) or mineralization (incorporation of calcium salts). Sclerotization occurs in all arthropods, being the only hardening mechanism used in the chelicerates and hexapods.

What is the arthropod tympanic membrane?

This forms a thin sheet of cuticle that functions like an eardrum in response to vibrations in the air. The sensory dendrites attached to the inner surface of the tympanum depolarize in response to vibrations of the membrane. Tympanal organs may be located on the forelegs, first abdominal segment, or metathorax.

What is the arthropod hemal system?

This includes a heart, arteries, sinuses, blood, and hemocoel. The tissues are bathed in the blood that nourishes them. The system functions in transporting nutrients, wastes, hormones, and sometimes gases. In the absences of a coelom, the hemocoel is the functional body cavity of arthropods.

What are symphyla?

This is a class of arthropod species found in moist soil and leaf litter in the most parts of the world. their permeable cuticle restricts them to humid habitats. These superficially resemble centipedes in being elongate and multisegmented.

What are pauropoda?

This is a class of arthropod species that are soft-bodied, nocturnal animals. These are widely distributed in both temperate and tropical regions in leaf litter, soil, damp wood, and under stones. All are minute. Most feed on fungi or decomposing plant tissue but some are predaceous.

What are aracnidia?

This is a class of arthropods that includes well-known animals such as spiders, scorpions, mites, and ticks. Almost all arachnids are terrestrial carnivores with some that have returned to an aquatic habitat. The epicuticle of these animals have become waxy to reduce water loss along with the use of book lungs and tracheae. Malpighian tubules and uricotely evolved to deal with the end product of nitrogen metabolism. Some appendages became adapted for terrestrial locomotion and an array of sensilla suitable for use in air appeared. Some unique innovations (silk, poison glands) evolved independently.

What are pycnogonida?

This is a class of arthropods that is exclusively marine also known as sea spiders. These have eight long legs and a small body, but otherwise would not be considered a spider. These are common benthic animals that occur from the intertidal zone to the deep sea. They live in all oceans, typically in bryozoans, hydroids, and anemones. Most are bottom dwellers that crawl about over irregular substrates as if on stilts. Some can swim by flapping their legs alternately up and down. Few are pelagic, some are interstitial, and some are commensal or ectoparasitic on other invertebrates.

What are articulata?

This is a class of brachiopods that have shells with processes with a blind sac. These have a complex hinge with interlocking teeth and sockets. There is a calcite shell while the periostracum lacks chitin. The dorsal valve usually has calcareous brachidia to support the lophophore. The shell is open and closed by the direct action of the adductor and abductor muscles. The pedicle is supported by connective tissue. There is no anus. Locally found species include Terebratalia transversa.

What are gymnolaemata?

This is a class of bryozoan that are mostly marine with a circular lophophore. Most live in coastal waters attached to surfaces. Those with fan-shaped colonies have cylindrical zooids. Those with encrusting colonies have flattened zooids. Locally Membranipora and Bugula (eel grass leaves) are found.

What are phylactolaemata?

This is a class of bryozoan. These are found exclusively in freshwater. Zooids are cylindrical while the lophophore is horseshoe-shaped. These have zooecium that is compressible, uncalcified, thin, or thin and sometimes gelatinous. The trunk coelom is continuous between zooids. Colonies are monomorphic with all zooids being autozooids. These have an important statoblast stage found if they are in a dry or hot environment.

What is the Xiphosura?

This is a class of chelicerata that are represented as horseshoe crabs. These are the largest modern chelicerata (up to 75 cm). These retain many of of the characteristics of stem chelicerate including living in an aquatic habitat. These crabs live in shallow marine water on soft bottoms where they plow through the upper surface of the sediment. These are not in fact true crabs.

What are cepalocarida?

This is a class of crustaceans also known as "head shrimp" that are epibenthic deposit feeders with undifferentiated trunk appendages. These live from subtidal to deep water as interstital (between grains, mud and sand). These are tiny of less than 4 mm in length.

What are remipedia?

This is a class of crustaceans also known as "oar child" found in undersea caves in the Bahamas, West Indies, and Yucatan Peninsula. So far all representatives have been found in water-filled caves connecting with the sea at one end and with freshwater ponds at the other. These are carnivores or scavengers. The large first antennae are biramous and bear chemosensory aesthetascs. The second antennae are paddlelike.

What are cirripedia?

This is a class of crustaceans also known as feather foot or barncles. Some compare the barnacle to a shrimp on its back. These are benthic marine animals. These inhabit a rigid calcareous shell that grows without molting, many are hermaphroditic and are sessile. These are crustaceans mostly because of the nauplius larva. This includes the Balanus (stalkless barnacle), Pollicipes (gooseneck barnacle), and Sacculina (parasitic)

What are chelicerata?

This is a subphylum of arthropoda that includes spiders, scorpions, harvestmen, mites, horseshoe crabs, and sea spiders. Most are terrestrial. This subphylum consists of classes Euchelicerata (Arachnida, Eurypterida, Xiphosura) and Pycnogonida.

What are myriapoda?

This is a superclass of mandibulata containing millipedes and centipedes. This includes classes such as diplopoda, chilopoda, symphyla, and pauropoda.

What are pentastomida?

This is a class of crustaceans also known as five mouth or tongue worms that are elongate, vermiform parasites of the nasal passages, sinuses, and lungs of vertebrates. All stages of the life cycle are obligatory parasites and most require an intermediate and definitive host. Around 90% parasitize reptiles (snakes, crocodiles, lizards). Only a few infect mammals and birds. The parasites feed on blood in the reptile but mucus and cells in mammals. There is usually a vertebrate but sometimes an arthropod intermediate host. These have been reported from North America, Europe, Australia, and Arctic but are largely tropical.

What are branchiura?

This is a class of crustaceans also known as gill tails or fish louse. These are intermittent ectoparasites on freshwater and marine fishes and occasionally tadpoles.

What are tantulocardia?

This is a class of crustaceans also known as head-shield shrimp. These are marine ectoparasites of deepwater copepods, isopods, and ostracods. These are tiny animals that do not exceed 1 mm in length with most being about 0.5 mm.

What are mystacocarida?

This is a class of crustaceans also known as mystery shrimp that are found mostly in the North and South Atlantic that are 0.5 to 1.0 mm in length for living in the interstices between sand grands in he intertidal zone. The body is long, cylindrical, and vermiform.

What are copeoda?

This is a class of crustaceans also known as oar foot that is mostly marine with a few freshwater and terrestrial forms (moss, soil-water films, leaf litter). These are tiny and range from less than 1 to about 5 mm although larger free living species have been found. Parasitic copepods attack various marine and freshwater animals. This dominates freshwater zooplankton. These are a major part of the diet of many marine animals. Calanus is a major free living copepod order that is an important food source.

What are ostracoda?

This is a class of crustaceans also known as oyster shrimp or seed shrimp. These are tiny microcrustaceans found in most aquatic habitats both freshwater and marine. These are completely enclosed in a bivalve carapace and resemble seeds or minuscule clams. Some are planktonic but most live on or near the bottom where they swim intermittently or crawl over or plow through the upper layer of mud and detritus from the shoreline to great depths. These may be suspension feeders, carnivores, detritivores, or herbivores. Some are commensal with other animals. Some are bioluminescent. This includes Cypris (marine or freshwater, benthic, no antennal notic, ventral valve margin is straight or concave, two pairs of antenna with well developed endopods and reduced exopods, mandibles and first maxillae lack filtering setae, second maxillae are sometimes leglike, one or two pairs of trunk appendages).

What are ascothoracida?

This is a class of crustaceans that are echinoderm (ecto) and coral (endo) parasites. The gut is adapted for sucking.

What are phyllopoda?

This is a class of crustaceans that are mostly freshwater that include tadpole and clam shrimps as well as water fleas. These species live where they are free from fish prey such as temporary ponds, ditches, cave pools, and alkaline lakes. These have a well-developed carapace shaped like that of a horseshoe crab.

What are anostraca?

This is a class of crustaceans that inhabits inland but not necessarily fresh water, including fairy and brine shrimp. These habitats tend to not have fish either because the habitat dries up periodically or because the water is too saline. Brine shrimp are more commonly known as sea monkeys. These tend to be relatively large ranging from 15-30 mm in length. There is no carapace present. These shrimp usually swim upside down but when experimentally light from below they will roll over and swim right side up.

What are holothuroidea?

This is a class of echinoderms that are the "hollow form", as known as sea cucumbers. Many burrow, crawl, occupy crevices, attach to hard surfaces, climb, or are pelagic. These lack arms and the oral surface and ambulacra are expanded aborally along the elongate polar axis. The oral pole does not lie against the substratum. These are worm shaped or vermiform and have calcarious spots internally for an endoskeleton. There is a decrease in the number of ossicles but contain a respiratory tree (bilateral pair, internal, ventilated by muscular pumping of the cloaca to cause an inrush of water through the anus, principle gas exchange site) and cuverian tubules (sticky tubules from anus, attached to base of one or both respiratory trees, releases when irritated or attacked). Tube feet are absent or reduced on one side of the body to allow for slow movement. These have five muscle bands or sections on the ambulacrum on the coelomic side of a radial canal. All muscles are smooth. Locally Cucumaria, Parastichopus, and Eupentacta are found.

What are Crinoidea?

This is a class of echinoderms that contains sea lilies, and feather stars. These are deep water species closely related to brittle stars. There are many found in fossils that are now extinct. These are radially symmetric, sessile, or semisessile suspension feeders that live with the mouth oriented upward. These collect food with the tube feet on their long often branched arms. The arms constitute most of the body with the disc being small and often inconspicuous. A long stalk attaches sea lilies to the substratum but the stalk tissues are primarily skeletal and may demand only a modest amount of metabolic energy. The sedentary habitats or slow space, heavily ossified, jointed appendages, and floral appearance confer on them a primordial elegance that has been retained in the present. Feather stars occur in shallow water and are common and spectacular members of coral-reef communities.

What is the class stellaroidea?

This is a class of echinoderms that includes the subclass Asteroidea and Ophiuroidea.

What are echinoidea?

This is a class of echinoderms that is the spiny form containing sea urchins and sand dollars. There are regular echinoids that are radially symmetrical (urchins) with long spines and are herbivores. Locally we find Strongylocentrotus. There is also irregular echinoids that are bilaterally symmetrical (sand dollars and sea biscuits) that have shorter spines and are deposit and filter feeders. These are bilaterally symmetrical mostly because of the repositioning of the anus to the rim or midway between the pole and rim as well as the body depression. Locally we fine Dendraster (sand dollar).

What are pterobranchia?

This is a class of hemichordates known as the feather gills or sea angels. These make small bryozoan-like colonies on hard surfaces mainly in deep water with ciliated tentacles, while being relatively uncommon. These have a cephalic shield with glands that produce tubes. This has a U shaped gut with most being colonial to phoronid like.

What are malacostraca?

This is a class of over half of the crustaceans. The head has five segments, the thorax has eight segments and the abdomen has 6 plus the telson, but in the most species the abdomen only has six segments. This class also has abdominal appendages with a carapace that may or may not be present with the amount of trunk covered varying. The first antenna is often biramous while the exopod of each second antenna is frequently a flattened antennal scale. The thoracic appendages are used for crawling or grasping well the exopod is lost and results in a pereopod that is uniramous. In most species one, two, or three anterior thoracic segments fuse with the head to form a cephalothorax with the appendages that are turned forward to become maxillipeds used in feeding. Usually the first five pairs of abdominal appendages are used for swimming, burrowing, creating a ventilating or feeding current, brooding eggs, or gas exchange. The pleopods are also present along with a uropod. The telson is the tail of the species. These contain compound eyes.

What are ascidiacea?

This is a class of urochordata known as the sea squirts that are common sessile marine animals throughout the world. these are either solitary or colonial. Most occur in shallow water where they attach to rocks, shells, pilings, and ship bottoms. These use the buccal and atrial siphons for the filter-feeding water stream. The tadpole larva resorbs the tail and notochord. These have a U-shaped gut and reversible heart (reverse blood flow, occurs every few minutes when heartbeats stop and then resume in opposite direction, average the supply of metabolites to tissues). Locally found species include the Aplidium, Boltenia, and Corella.

What are thaliacea?

This is a class of urochordata known as the swimming squirts. These can be planktonic, solitary, or colonial. These includes the orders Salps (prism shaped zooids, single mid-dorsal gill bar and no side walls, feed using endostylar mucous net, found in upper levels of all oceans but more common in warmer seas), Pyrosomes (brilliantly luminescent colonies when disturbed, hollow tube closed at one end, zooids embedded in wall), and Doliolids (barrel-shaped zooids, prevent backflow through buccal siphon, clonal and sexual phases, solitary and colonial forms, tadpole larva). Some are luminescent.

What are Limulus polyphemus?

This is a common horseshoe crab found in shallow water along the North American Atlantic coast.

What is hemocyanin?

This is a copper-based pigment used for respiration. Hemoglobin is found in a few crustaceans and insects. Respiratory pigments are in simple solution in the blood plasma, rarely in corpuscles.

What are the characteristics of the arthropod heart?

This is a mid-dorsal muscular tube in the pericardial sinus. The length of the heart varies. The heart wall is composed of circular muscles. Peristaltic contractions of these muscles propagate from posterior to anterior and propel the blood anteriorly from the heart. The heart is perforated by paired ostia equipped with one-way valves permitting blood to enter the heart from the pericardial sinus but preventing flow in the reverse direction. The ostia number is reduced and segmental heart arrangement lost in most arthropods. Elastic suspensory ligaments or contractile alary muscles extend from the outside of the heart to the nearby exoskeleton or connective tissue.

Wha are Kamptozoa?

This is a phylum of 150 small, sessile, mostly colonial marine animals. These are sometimes known as the nodders because of their amusing habit of bobbing on the end of their stalk. These live attached to firm substrata with many being epizoic or commensal on sponges, polychaetes, bryozoans, ascidians, and other marine invertebrates. These have interconnected zooids that are somewhat ovoid or boatshaped. The upper ventral margin of the calyx bears an encircling tentacular crown of 8 to 30 solid tentacles that are extensions of the body wall. Both the mouth and anus are located within the ring of tentacles. These are filter feeders that use the tentacles to capture suspended organic particles and small phytoplanketon using a downstream collecting system for food gathering

What are hemichordata?

This is a phylum of acorn and tongue worms. These are marine worms with a proboscis, collar and trunk that can be up to 1.5 meters. These are suspension or deposit feeders.

What are phoronida?

This is a phylum of lophophorates of wormlike, sessile, benthic animals found only in the sea. Externally they are bilaterally symmetrical but internally they are asymmetrical with left-side dominance. Phoronoids live in secreted chitinous tubes buried in sand or attached to rocks, shells, and other objects in shallow water. Some have bright green lophophores. Some species bore into mollusc shells or calcareous rocks. These are 2 to 20 cm in length but only 1 to 2 mm in diameter. Most are found in the relatively shallow water of the continental shelf. Primitively the lophophore is a circular tentacle-bearing ridge around the mouth and epistome but frequently the circular ring is collapse inward dorsally to form a crescent or horseshoe of two parallel rows of tentacles with the horns of the crescent directed dorsally and rolled up as a spiral on each side. The lophophore is used in gas exchange and feeding. The hemal system consists of blood confined to definite vessels. A ring vessel at the base of the lophophore gives rise to blind-ended tentacular vessels with a large descending and ascending vessel. The blood contains hemocytes that have hemoglobin. The intraepidermal nervous system has a nerve ring at the base of the lophophore to supply the tentacles and body-wall muscles with nerves. There is a left nerve cord containing giant axons in all species. These are hermaphroditic species where gametes are shed into the trunk coelom to escape via the metanephridia for internal fertilization followed by brooding in the lophophore or release into the plankton. Locally found species include the phoronis and phoronopsis.

What are bryozoa?

This is a phylum of lophophorates that are benthic and colonial with most species living attached to firm substrata but one genus is solitary and a few form motile colonies. The colonies may be large but each is composed of numerous tiny zooids and are unmistakably animal like. There are 5,000 living and 15,000 fossil species. Most are marine but some are freshwater with a calcareous exoskeleton. These can produce asexually to produce colonies or sexually through external fertilization for larvae production. There is no respiratory or circulatory system, with gas exchange occurring across the exposed body surface, especially the lophophore while the coelomic fluid coelomocytes engulf and store waste materials but there is no heart or typical blood vessels.

What are echinodermata?

This is the largest exclusively marine phylum found in estuarine locations from shallow marine to deep sea. These are benthic except for the larval stage. This is the largest deuterostome invertebrate group with at least a dozen classes known only from fossils.

What are brachiopoda?

This is a phylum of lophophorates that resemble bivalve molluscs that have suspension feeding with a mantle, mantle cavity, and bivalved calcareous shell. The two mineralized valves enclose a soft body with dorsal and ventral valves. These are marine, benthic suspension feeders found from the intertidal zone to the deep sea but most live on the continental shelf. These are solitary and most species live attached to the surface of rocks or other hard substrata but some live in vertical burrows in sand or mud bottoms. These are relatively large and thick-bodied with an exceptionally large lophophore to increase the surface area to volume ratio. The dorsal valve fits over the ventral valve with a posterior aperture with the pedicle (attachment stalk). These are dioecious and have an open circulatory system with a heart with hemerythrin in the coelomic fluid. There are 30,000 species in the fossils.

What are chordata?

This is a phylum that is the largest and most successful of all deuterostomes. These have a number of characteristics that are present for at least part of its life including: notochord (flexible but incompressible rod), dorsal hollow nerve cord (directly above and in contact with notochord, extends from anterior of brain to tail), pharyngeal gill slits, and postanal tail (often lost in adults). These are clearly deuterostomes with radial cleavage and coelom.

What is proecdysis?

This is a preparatory phase in which the most extensive changes occur. The animal enters from the intermolt condition and exits with the old cuticle detached but still covering the animal and the new cuticle partially formed. During proecdysis the animal does not feed and subsists on food reserves. Blood calcium levels rise due largely to the reclamation of calcium from the old exoskeleton. To initiate proecdysis the epidermis secretes a new epicuticle and releases molting fluid between the new and old epicuticle. Molting fluid is a mixture of chitinase and proteases that separates the two layers by hydrolyzing the old cuticle. The hydrolysis products are resorbed by the epidermis through the new epicuticle but the new epicuticle protects the epidermis from the enzymes. A new exocuticle is secreted while the old endocuticle is being hydrolyzed throughout this stage. At this point the animal is encased within old and new exoskeletons both consisting primarily of epicuticle and exocuticle since the new endocuticle has not yet been secreted and the old endocuticle has been hydrolyzed.

What is the zooecium for bryozoa?

This is a protective exoskeleton secreted by the metasome of the epidermis. this can be organic or mineral (calcium carbonate). There is an orifice through which the introvert and lophophore can be extended. An operculum that can be closed by an occlusor muscle is sometimes found here.

How do arthropods get their body color?

This is a result of pigments in the cuticle or the subepidermal connective tissue. Cuticular pigments are deposited in the cuticle as its secreted and once present their appearance cannot be altered. Subepidermal pigments are contained within chromatophore cells that are under neurohormonal control with altering appearance by expanding or contracting the chromatophores. Color of underlying tissues and even hemoglobin in the blood may be visible externally if the cuticle is thin and transparent enough. Very fine parallel scratches in the epicuticle that refract light of specific wavelengths can be responsible for producing an iridescent color when illuminated by white light even though no pigments are present.

What are the characteristics of the Onychophora subterminal mouth?

This is a shallow prebuccal depression on the vetnral surface of the heat. The opening to the depression is surrounded by lipds. When feeding, onychophorans lacerate the prey with the mandibles and flood it with saliva. The saliva contains hydrolytic enzymes and mucus secreted by a pair of salivary glands, which open by a single duct into the anterior foregut. The salivary glands are modified saccate nephridia of the head segments and consist of an end sac with podocytes and a duct. Digestion begins externally.

What are the arthropods hemocoel?

This is a space in the connective tissue compartment derived from the embryonic blastocoel with contributions from the mesoderm. It is filled with blood. This space is not lined by either an endothelium or other cells and is usually not restricted to narrow vessels. A thin, acellular basal lamina typically covers the surface of the tissues of the hemocoel and separates them from the blood. These laminae when close together define channels or vessels. There are patterns of blood flow and vessels may be present. The system is often referred to as being open. The blood found here is known as hemocyanin.

What is intermolt?

This is a stage that is largely free of activities directly involved with molting and may be long or short depending on the species. During intermolt the animal engages in its normal day-to-day activities including feeding, accumulation of food reserves, and reproduction if it is sexually mature. This is the period in which tissue growth occurs.

What are asteroidea?

This is a subclass of stellaroidea as known as star form that includes the sea stars. Vancouver Island has the greatest number and diversity. These can have 5 to 40 rays that are carnivorous with papulae (specialized gills associated with the perivisceral coelom, on the aboral surface of the thick arms, similar to tube foot but lacks sucker). Locally we find Pisaster, Pycnopodia, and Leptasterias. The rays are hollow and project from a central disc. These crawl about over rocks and shells or live on sandy or muddy bottoms. These occur worldwide, largely in coastal waters but the northeast Pacific Ocean has the greatest diversity of asteroids. These commonly are red, orange, blue, purple, or green but can exhibit a combination of colors.

What are ophiuroidea?

This is a subclass of stellaroidea known as snake form containing brittle stars that are common in many benthic marine habitats. This is the largest extant class with many undescribed species. This can live on, under, and between rocks, shells, and living organisms as well as in sediments. These are mostly slender five-armed stars with a distinct central disc that may be circular or pentagonal. These have increased mobility with the disc held above the substratum while one or two arms extend forward and one or two trail behind with the rowing movement of the rest of them propels the body forward in leaps or jerks. The spines on the arms provide traction. They feed through deposit (tube feet to collect substratum particles, compact into food balls and move toward mouth) and filter feeding (mucus on the arms, cilia moves it downward, arms wrap around prey). Locally we find Ophiocoma and Gorgoneocephalus.

What are the characteristics of the arthropod brain?

This is a syncerebrum consisting of the fused, paired ganglia or neuromeres of two or three anterior head segments. The protocerebrum (paired ganglia of the acron) is the anteriormost region of the brain. It receives sensory nerves from the various types of arthropod eyes and processes optical input. The commissure connecting the ganglia of the right and left sides of the protocerebrum is preoral or anterior to the mouth. The deutocerebrum is the integration center for the first head segment to connect with the sensory and motor nerves of the antenna of crustaceans and tracheates. The tritocerebrum belongs to the second head segment bearing the chelicerae or second antennae.

What is molting?

This is also called ecdysis and is a central feature of arthropod life to allow these species to increase in size. The crustacean molt cycle has four basic stages known as intermolt, proecdysis, ecdysis, and postecdysis. This is dangerous because the muscles have no rigid point of attachment making movement difficult or impossible during postecdysis making them vulnerable for predation. This is also dangerous because many arthropods are unsuccessful at extracting themselves from the exuvium and remain trapped in it until they die or get captured by a predator. The organism is known as an instar during the time between two intermolts, with the length of this time increasing as the animal becomes older and larger some molting throughout their life (lobster, crabs) or for a fixed number of instars that cease after achieving sexual maturity (insects, spiders)

What are isopoda?

This is an order of malacostraca that live in the sea to act in benthic habitats while others are found in freshwater communities or terrestrial habitats. Pill bugs are the most succesful terrestrial crustacean. These are flattened vertically and are stable when out of water. Idotea are marine benthic isopods with uropods ventral to the pleotelson to form opercula to enclose and protect the branchial chamber and pleopods. The pleotelson is often elongated.

What is cryptobiosis?

This is characterized by desiccation, reduced metabolic rate, and enhanced resistance to adverse environmental conditions including drought and temperature extremes. The shriveled dormant cryptobiotic tardigrade is known as a tun. The tardigrades can live in this state for as long as 10 to 100 years during which has periods of activity alternating with periods of cryptobiosis. This cryptobiosis allows for dispersal as it is easily transported by the wind or other organisms.

What is the arthropod compound eye?

This is composed of ommatidia (light-recieving units) with its own lens or cornea. These are found in trilobites, horseshoe crabs, arachnids, crustaceans, insects, and some myriapods. These are usually flush with the surface of the head and are said to be sessile. In some crustaceans the eyes are at the ends of eyestalks from where they have a much wider field of view.

What is the procuticle?

This is composed of protein and chitin bound together to form a complex glycoprotein. It is much thicker than the epicuticle and is responsible for most of the thickness and strength of the exoskeleton. It is composed of the outer exocuticle (proteins hardened by sclerotization in places where strength and rigidity are needed) and the inner endocuticle (less protein and more chitin, often mineralized with calcium carbonate in crustaceans).

What are arthropod gills?

This is found in crustacea and aquatic insects. These are usually modified appendages.

What is the superposition eye?

This is modified to collect and concentrate the light from several corneas onto a single ommatidium. The discontiguous cone and rhabdome are connected by a cone stalk. The two screening pigments are concentrated in a small volume of their respective cells, minimizing their effect. They do not form a curtain of pigments separating adjacent ommatidia. Light can pass from one ommatidium to another causing a rhabdome to respond to light that entered several different ommatidia. The crystalline cone tends to be twice as long as its focal length and there is considerable space between the end of the cone and the rhabdome, permitting the bent light rays to cross from the cyrstalline cone of one ommatidium to the rhabdome of another. The retinular cells are much shorter than those in apposition eyes and are restricted to the base of the ommatidium. These adaptations for low light intensity make it more likely that a rhabdome will be activated, even by a weak light source. In this mode, a single point of light is not associated with a single point in a mosaic image. A blurred image, or no image, is formed, but the brain is aware that there is light in the environment and can tell if it is moving. These are found in nocturnal species, deep-water species, and others that live in low light intensities.

What is the male reproductive system of onychophora?

This is paired proximally and single distally. The testes, seminal vesicles, and vasa efferentia join to form a single vas deferens which enlarges to become the ejaculatory duct. The ejaculatory duct opens to the exterior via the male gonopore on the posterior ventral surface. Sperm are flagellated with axonemal microtubules in the typical 9+2 pattern.

What is ecdysis?

This is the actual shedding of the old exoskeleton. This is usually brief although difficult and hazardous and often occurring in a protected retreat or burrow. In certain well-defined areas of the old exoskeleton, the exocuticle is very thin and, once the endocuticle has been removed by hydrolysis, only the thin epicuticle remains in areas known as ecodysial lines with a constant location for each species. The uptake of water or air raises the blood pressure in the hemocoel and causes the animal to swell, stretching the pliant new cuticle and splitting the old cuticle along the ecdysial lines. The animal struggles out of the old cuticle and frequently ingests it to reclaim the remaining calcium salts and organic compounds. The new cuticle is soft, wrinkled, and incomplete and before it hardens may require additional stretching to accommodate future tissue growth.

What is cephalization?

This is the development of an anterior tagma responsible for sensory reception, neural integration, and feeding. This is a strong tendency in arthropod evolution. The head is made up of five to six metameres. The head or its equivalent contains the brain (segmental ganglia), anterior gut, and the sensory and feeding appendages. The eyes are on the acron.

What is the ommatidium?

This is the individual self-contained and independent light-detecting unit of the compound eye. There may be 15 to thousands of these units per eye. These are elongate and rod-shaped. Each of these contains its own focusing system, light-transmitting system, a collection of light-sensitive photoreceptor cells, and screening pigment to isolate the unit optically from adjacent ommatidia.

What is lophophorata?

This is the superphylum containing Brachiopoda, Bryozoa, and Phoronida. These are sessile marine or freshwater suspension feeders enclosed in a secreted exoskeleton, shell, or tube with a single aperture. The mouth, anus, nephridiopores, and gonopores are at the apertural end of the body, close the the opening of the enclosing tube or exoskeleton. The gut is bent into a U bringing the anus into proximity with the mouth at the apertural end. The anus is dorsal to the mouth. On or more pairs of metanephridia or coelomoducts may be present and if so, their pores are also anterior. These feed using a lophophore or crown of hollow, ciliated tentacles encircling the mouth. The lophophore is an upstream collecting system for suspension feeding, ciliated tentacles arranged as a funnel with the small end surrounding the mouth and its large end open to the water. Lateral cilia on the sides of the tentacles create a flow of water into the large, open end of the funnel then outward between the tentacles to exit the funnel to collect planktonic food in a mucus material. The body is divided into two or three regions each with a coelomic cavity. The first region is the mesosome with most of the body posterior to this (posterior metasome, trunk). The epistome (tiny anteriodorsal lobe) may preceded the first region and overhang the mouth. The third region is often called the protocoel and is only found in some groups. The coelom for these animals is known as mesocoel. These perform gas exchange as well.

What is tagmosis for arthropoda?

This is the tendency to organize segments into regions having similar structure, function, and appendages. Each group of similar segments is a tagma. The trunk is divided into a thorax and abdomen. In many arthropods some or all of the thoracic segments are united with the head to form the cephalothroax. All hexapods have a body divided into the head, thorax, and abdomen whereas chelicerates have a cephalothorax and abdomen while the crustaceans have various arrangements of head, thorax, and abdomen.

What are cephalochordata?

This makes up 10% of chordates, a subphylum that are lancelets (fish-like, burrowing in marine sand) that use filter-feeding with a weak swimming ability. These are found in tropical and temperate oceans worldwide in intertidal or shallow subtidal sand. These have all the chordate characteristics plus photoreceptors. A common form is Branchiostoma (Amphioxus, opposite points, tapered at both ends).

How does mating occur in tardigrades?

This mating and oviposition occur in conjunction with molting by the female. In aquatic species, males may deposit sperm in the recently shed female exuvium that contains eggs. In most terrestrial species copulation occurs and the male intromits sperm into the female reproductive tract before ecdysis is complete for internal fertilization. One to 30 eggs are laid at a time depending on the species. Eggs may be deposited in old exuvium or attached to some substratum. Some species produce thin-shelled eggs when environmental conditions are favourable and thick-shelled resistant eggs when conditions are adverse. Terrestrial species eggs typically possess a thick, sculptured shell that resists the frequent periods of desiccation.

What are the excretion characteristics of echinodermata?

This occurs across the skin, through podia, or using an axial organ.

What is the arthropods color vision?

This uses photoreceptive pigments of different retinula cells that are specialized to respond to specific wavelengths of light. Some are able to response to UV light as well as IR light.

What is the historical method of classification?

This uses the Linnean scheme with 34 phyla. This is mophology based.

How does spermatophore transfer occur in onychophora?

This varies with species. In some that lack seminal receptacles the spermatophores are attached to the outside of the female's body. Amebocytes from the female's blood secrete enzymes to hydrolyze an opening in the body wall directly under the spermatophore. The sperm enter the hemocoel through this opening and make their way to the ovary, where fertilization occurs. In others the spermatophore is placed in the female gonopore. Sperm transfer with seminal receptacles is not understood. Males of some taxa have what appears to be a penis but it has not been observed in operation. Males also possess two pairs of accessory genital glands that open in the vicinity of the gonopore.

What are parasitic hexapoda?

Ticks, lice, fleas, botflies, tsetse flies, mosquitoes (botfly, malaria, zika)

What is the Giant clam, Tridacna gigas, case study?

To manage these species it was a cultural approach needed by working with local village elders and governments. This created a marine protected area.

What is the epicuticle?

this is a thin, complex, water-resistant or water-proof layer of protein, lipoprotein, lipid, and sometimes wax but no chitin. In terrestrial insects and arachnids the epicuticle includes an outer layer of wax that renders it impermeable to water and gas. The wax, secreted by gland cells in or near the epidermis and delivered to the surface by ducts, protects the organism from water loss in a dry environment. In freshwater species it prevents or restricts the osmotic influx of water into the organism. In areas such as the trachaea and gill surfaces the epicuticle is thin and the wax layer is absent. The waterproof integument is one of the adaptations responsible for the enormous success of the hexapods and chelicerates in terrestrial environments.