Chapter 33 bio

catelunida

"chain worms," are mostly free-living and reproduce asexually by budding (small clade; about 100 species)

Tapeworms

- Parasites of vertebrates - Absorb nutrients directly from the host's intestine (have no mouth or gastrovascular cavity) - The scolex contains suckers and hooks for attaching to the host - Proglottids are units that contain sex organs and form a ribbon behind the scolex - Fertilized eggs, produced by sexual reproduction, leave the host's body in feces

Trematodes

- Parasitize a wide range of hosts - Most have complex life cycles with alternating sexual and asexual stages - Trematodes that parasitize humans spend part of their lives in snail hosts - Can survive in humans for 40+ years - Produce surface proteins that mimics the host's - Manipulate the host's immune system to tolerate its presence - Eg. Schistosoma mansoni (blood fluke)

open circulatory system

A circulatory system in which fluid called hemolymph bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid

alimentary cannal

A complete digestive tract, consisting of a tube running between a mouth and an anus. - property of rotifiers

choanocyte

A flagellated feeding cell found in sponges. Also called a collar cell, it has a collar-like ring that traps food particles around the base of its flagellum.

parthenogenesis

A form of asexual reproduction in which females produce offspring from unfertilized eggs

planarians

A free-living flatworm found in ponds and streams. Can reproduce: - asexually - sexually - hermaphrodites

mesohyl

A gelatinous region between the two layers of cells of a sponge.

exoskeleton

A hard encasement on the surface of an animal, such as the shell of a mollusc or the cuticle of an arthropod, that provides protection and points of attachment for muscles.

osculum

A large opening in a sponge that connects the spongocoel to the environment.

eumetazoan

A member of a clade of animals with true tissues. All animals except sponges and a few other groups are eumetazoans

arachnid

A member of a subgroup of the major arthropod clade Chelicerata. Arachnids have six pairs of appendages, including four pairs of walking legs, and include spiders, scorpions, ticks, and mites. Gas exchange in spiders occurs in respiratory organs called book lungs Many spiders produce silk, a liquid protein, from specialized abdominal glands

water vascular system

A network of hydraulic canals unique to echinoderms that branches into extensions called tube feet, which function in locomotion and feeding. - unique to echinoderms

Phylum Nematoda (roundworms) trichinella spiralis

A parasite that can be acquired by humans from undercooked pork (trichinosis)

Ectoprocts

A sessile, colonial lophophorate; also called a bryozoan are sessile colonial animals that superficially resemble clumps of moss Are among the most widespread marine sessile animals; also in freshwater A hard exoskeleton encases the colony, and some species are reef builders

echinoderm

A slow-moving or sessile marine deuterostome with a water vascular system and, in larvae, bilateral symmetry. Echinoderms include sea stars, brittle stars, sea urchins, feather stars, and sea cucumbers.

radula

A straplike scraping organ used by many molluscs during feeding.

Clade Myriapoda (myriapods - millipedes and centipedes)

A terrestrial arthropod with many body segments and one or two pairs of legs per segment. Millipedes and centipedes are the two major groups of living myriapods Have a pair of antennae and three pairs of appendages modified as mouthparts

incomplete metamorphosis

A type of development in certain insects, such as grasshoppers, in which the young (called nymphs) resemble adults but are smaller and have different body proportions. The nymph goes through a series of molts, each time looking more like an adult, until it reaches full size. Many insects undergo metamorphosis during their development After the final molt, the wings develop and the insect becomes sexually mature

mantle cavity

A water-filled chamber that houses the gills, anus, and excretory pores of a mollusc.

five clades of echinoderms

A) Asteroidea (sea stars and sea daisies) B) Ophiuroidea (brittle stars) C) Echinoidea (sea urchins and sand dollars) D) Crinoidea (sea lilies and feather stars) E) Holothuroidea (sea cucumbers)

Class Gastropoda - snails and slugs

About 75% of all living molluscs Most are marine, but there are many freshwater and terrestrial species Gastropods move slowly by a rippling motion of the foot or by cilia Most have a single, spiraled shell that functions in protection from injury, dehydration, and predation Most are herbivores, but some species use modified radula to feed on prey

Three main parts of mollucs

All have a similar body plan with three main parts: Muscular foot Visceral mass Mantle

amoebocytes

An amoeba-like cell that moves by pseudopodia and is found in most animals. Depending on the species, it may digest and distribute food, dispose of wastes, form skeletal fibers, fight infections, or change into other cell types.

Filter feeders

An animal that feeds by using a filtration mechanism to strain small organisms or food particles from its surroundings. - sponges

chelicerates

An arthropod that has chelicerae and a body divided into a cephalothorax and an abdomen. Living chelicerates include sea spiders, horseshoe crabs, scorpions, ticks, and spiders. Named for clawlike feeding appendages called chelicerae The earliest chelicerates were eurypterids (water scorpions) Most marine chelicerates (including eurypterids) are extinct, but some species survive today, including horseshoe crabs

protonephridium

An excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings.

book lung

An organ of gas exchange in spiders, consisting of stacked plates contained in an internal chamber

Class Bivalvia - clams, oysters, mussels, and scallops

Aquatic Have a shell divided into two halves drawn together by adductor muscles Some have eyes and sensory tentacles along the edge of their mantle Mantle cavity contains gills that are used for feeding and for gas exchange Most species are sedentary, but some have limited motility

Phylum Nematoda (roundworms) Ascaris lumbricoides

Ascaris lumbricoides (causes ascariasis / ascaridosis in humans) About 1 in 7 people worldwide are infected Often, no symptoms if infection is mild

barnacles

Barnacles are mostly sessile crustaceans and have a cuticle that is hardened into a calcium carbonate shell

Phylum cnidaria

Both sessile and motile forms including jellies, corals, and hydras Exhibit a relatively simple diploblastic, radial body plan The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity A single opening functions as mouth and anus

centipedes

Centipedes are carnivores Centipedes have one pair of legs per trunk segment Poison claws on the foremost trunk segment paralyze prey and aid in defense

Four main classes of phylum mollusca

Class Polyplacophora - chitons Class Gastropoda - snails and slugs Class Bivalvia - clams, oysters, mussels, and scallops Class Cephalopoda - squids, octopuses, cuttlefish, and chambered nautiluses

Phylum annelida

Coelomates with bodies composed of a series of fused rings Modern classification: Errantia (mostly polychaetes) Sedentaria (mostly oligochaetes and leeches) "little rings"

Phylum Chordata (lancelets, tunicates, and vertebrates)

Consists of two basal groups of invertebrates as well as vertebrates Bilaterally symmetrical coelomates with segmented bodies Chordates did not evolve from echinoderms, but have evolved separately from them for at least 500 million years

Anthozoans

Corals and sea anemones Occur only as polyps Corals often form symbioses with algae (zooxanthallae) and secrete a hard exoskeleton (external skeleton) Each generation grows on the skeletal remains of the previous generation, forming "rocks" that provide habitat for other species

crustacean

Crustaceans (crabs, lobsters, shrimps, barnacles, and others) live in marine, freshwater, and terrestrial environments Many crustaceans have highly specialized appendages Small crustaceans exchange gases through the cuticle; larger crustaceans have gills Most crustaceans have separate males and females

Three major clades of bilaterian animals

Deuterostomia, Lophotrozoa, and Ecdysozoa

trochophore larval stage

Distinctive larval stage observed in some lophotrochozoan animals, including some annelids and molluscs.

earthworms (sedentaria)

Eat through soil, extracting nutrients as the soil moves through the alimentary canal Hermaphrodites but cross-fertilize Some reproduce asexually by fragmentation

Phylum nematoda

Found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals Have an alimentary canal, but lack a circulatory system Body wall muscles are all longitudinal, and their contraction produces a thrashing motion

Phylum Platyhelminthes (flatworms)

Free-living species live in marine, freshwater, and damp terrestrial habitats Many flatworms are parasites (e.g. flukes and tapeworms) Unlike most triploblastic animals, flatworms are acoelomates (lack a body cavity) Excretory apparatus: protonephridia - networks of ciliated tubules that pull fluid through ducts opening to the outside Dorsoventrally flattened body shape - all cells are close to water in the surrounding environment or in their gut (maximized surface area)

Class Cephalopoda - squids, octopuses, cuttlefish, and chambered nautiluses

Have a closed circulatory system, well-developed sense organs, and a complex brain Ammonites were common but went extinct at the end of the Cretaceous (65.5 mybp) Most squids are less than 75 cm long, but some species can grow from 10 to 14 m long

clade Ophiuroidea (brittle stars)

Have a distinct central disk and long, flexible arms that they use for movement Some species are suspension feeders, while others are predators or scavengers

insects

Hexapoda is an enormous clade including insects and their relatives Insects live in almost every terrestrial habitat and in fresh water; flying insects fill the air They are rare in marine habitats The internal anatomy of an insect includes several complex organ systems

Acanthocephalans

Highly modified rotifers Sexually reproducing parasites of vertebrates Lack a complete digestive tract Less than 20 cm long Called "spiny-headed worms" after the curved hooks on the proboscis

nematocyst

In a cnidocyte of a cnidarian, a capsule-like organelle containing a coiled thread that when discharged can penetrate the body wall of the prey.

lophophore

In some lophotrochozoan animals, including brachiopods, a crown of ciliated tentacles that surround the mouth and function in feeding.

Rotifiers

Inhabit freshwater, marine, and damp soil habitats Smaller than many protists but are truly multicellular and have specialized organ systems Have an alimentary canal, a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom Rotifers reproduce by parthenogenesis (females produce offspring from unfertilized eggs) or sexually Some species are all-female species

facts about insects

Insects diversified rapidly following the evolution of flight 359-252 million years ago (Carboniferous and Permian periods) An animal that can fly can escape predators, find food, and disperse to new habitats much faster than organisms that can only crawl Insects evolved flight without sacrificing a pair of walking legs because wings are an extension of the cuticle Periods of rapid insect diversification followed radiations of the plants on which they fed The diversity of insect mouthparts in the fossil record indicates that specialized modes of feeding evolved in response to gymnosperm (non-flowering plants) diversification A later insect radiation appears to have been stimulated by the expansion of flowering plants about 100 million years ago Insect and plant diversity declined during the Cretaceous mass extinction, but has been increasing in the 66 million years since

Phylum Arthropoda (arthropods)

It is estimated that there are about a billion billion (1018) arthropods living on Earth More than 1 million species have been described, and two out of every three known species of animals are arthropods Found in nearly all habitats of the biosphere A segmented ecdysozoan with a hard exoskeleton and jointed appendages. Familiar examples include insects, spiders, millipedes, and crabs.

E) Holothuroidea: Sea cucumbers

Lack spines, have a very reduced endoskeleton, and do not look much like other echinoderms Have five rows of tube feet; some of these are developed as feeding tentacles

Dugesia

Live in fresh water and prey on smaller animals Have light-sensitive eyespots and centralized nerve nets

millipedes

Millipedes eat decaying leaves and plant matter Millipedes have many legs, with two pairs per trunk segment

clade errantia

Most are mobile marine predators or grazers Many have a pair of paddle-like or ridge-like structures called parapodia ("beside feet") on each body segment (some sedentarians also have parapodia) Each parapodium has numerous chaetae, bristles made of chitin

reproduction in insects

Most insects have separate males and females and reproduce sexually Individuals find and recognize members of their own species by bright colors, sound, or odors Fertilization is generally internal In some species copulation occurs; in others, the male deposits a sperm packet that the female picks up Eggs are generally laid on a food source

leeches (sedentaria)

Most species live in freshwater; some are marine or terrestrial Include predators of invertebrates and parasites that suck blood Some parasitic leeches slit the skin of their host and secrete an anesthetic to prevent detection Secrete another chemical (hirudin, an anticoagulant)

Echinoidea (sea urchins and sand dollars)

No arms, but have five rows of tube feet Use their spines for locomotion and protection Feed on seaweed using a jaw-like structure on their underside Sea urchins are roughly symmetrical; sand dollars are flat disks

chelicerae

One of a pair of clawlike feeding appendages characteristic of chelicerates.

tube foot

One of numerous extensions of an echinoderm's water vascular system. Tube feet function in locomotion and feeding.

mantle

One of the three main parts of a mollusc; a fold of tissue that drapes over the mollusc's visceral mass and may secrete a shell. See also foot and visceral mass.

foot

One of the three main parts of a mollusc; a muscular structure usually used for movement. See also mantle and visceral mass.

visceral mass

One of the three main parts of a mollusc; the part containing most of the internal organs. See also foot and mantle.

Class Polyplacophora - chitons

Oval-shaped marine animals encased in an armor of eight dorsal plates Use their foot like a suction cup to grip rock, and their radula to scrape algae off the rock surface

origins of artrhopods

Over time, segments became functionally united into "body regions" specialized for feeding, walking, or swimming The diversity of arthropod body plans was more likely driven by changes in the sequence or regulation of existing Hox genes

Lophophorates

Phylum Ectoprocta - ectoprocts, aka bryozoans Phylum Brachiopoda - brachiopods Have a lophophore, a crown of ciliated tentacles around their mouth used for feeding Lophophorates have a true coelom

Phylum syndermata

Rotifiers and acanthocephalans

Crinoidea (sea lilies and feather stars)

Sea lilies live attached to the substrate by a stalk Feather stars can crawl using long, flexible arms Both use their arms in suspension feeding Crinoidea have changed little over the course of evolution

clade asteroidea

Sea stars (aka star fish) have multiple arms radiating from a central disk The undersurface of each arm bears tube feet, which grip a substrate with adhesive chemicals Sea stars feed on bivalves by prying them open with their tube feet, everting their stomach, and digesting their prey externally with digestive enzymes Sea stars can regrow lost arms Sea daisies are a group of armless species; only three species are known Sea daisies live on submerged wood and absorb nutrients through a membrane that surrounds their body

Phylum Echinodermata (echinoderms - sea stars, sea urchins, sea cucumbers, etc)

Slow-moving or sessile marine animals A thin epidermis covers an endoskeleton of hard calcareous plates Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion and feeding Males and females are usually separate, and sexual reproduction is external

Mollusca

Soft-bodies animals; most are protected by a calcium carbonate shell Most are marine; some slugs and snails are terrestrial and some inhabit freshwater Most have separate sexes (gonads are located in the visceral mass), but many snails are hermaphrodites Trocophore = ciliated larval stage in many molluscs

Phylum sedentaria

Tend to be less mobile than errantians Some species burrow into the substrate, while others live in protective tubes Tube-dwelling sedentarians often have elaborate gills or tentacles used for filter feeding Contains the leeches and the earthworms

Clade Pancrustacea (crustaceans and insects

Terrestrial insects are more closely related to crustaceans than myriapods Some lineages of crustaceans are more closely related to insects than other crustaceans A member of a diverse arthropod clade that includes lobsters, crabs, barnacles and other crustaceans, as well as insects and their six-legged terrestrial relatives.

Phylum Arthropoda (arthropods) General characteristics

The appendages of some living arthropods are modified for functions such as walking, feeding, sensory reception, reproduction, and defense These modified appendages are jointed and come in pairs Body is completely covered by the cuticle, an exoskeleton made of layers of protein and the polysaccharide chitin When an arthropod grows, it molts its exoskeleton Evolution of the exoskeleton in early arthropods enabled them to be among the first animals to colonize land Its relative impermeability to water helped prevent desiccation Its strength provided support without reliance on the buoyancy of water Arthropods have eyes, olfactory receptors, and antennae that function in touch and smell Arthropods have an open circulatory system in which hemolymph is circulated into the spaces surrounding the tissues and organs A variety of organs specialized for gas exchange have evolved in arthropods

Medusa

The floating, flattened, mouth-down version of the cnidarian body plan. the alternate form is the polyp

complete metamorphosis

The transformation of a larva into an adult that looks very different, and often functions very differently in its environment, than the larva. Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar The larval stage looks entirely different from the adult stage Metamorphosis from larva to adult occurs during a pupal stage

decapods

are all relatively large crustaceans (e.g. lobsters, crabs, crayfish, and shrimp) the cuticle of decapods are hardened by calcium carbonate

Two lineages of platyhelminthes

catelunida and rabditophora

poiyps

cylindrical forms that adhere to the substrate by the aboral end of their body( the end the mouth) and extend their tentacles, waiting for prey. - Hydras and sea anemones

isopods

e.g. pillbugs) are one of the largest groups of crustaceans. abundant in habitats at the bottom of the deep ocean

Deuterostmia

hemichordates( acorn worms), echinoderms (sea stars), and chordates( vertebrates and invertebrates)

Phylum Nematoda (roundworms) Necator americanus

hookworm Intestinal parasite, often asymptomatic

Rhaditophora

include both free-living and parasitic species (most flatworms; about 20,000 species)

Planktonic crustaceans

include many species of copepods, which are among the most numerous of all animals

Ecdyzozoa

include nematodes, arthropods and other ecdyzoan phyla - secrete external skeletons

Phylum Nematoda (roundworms) Enterobius vermicularis

pinworm; causes enterobiasis Infects about 1 in 10 people worldwide Asymptomatic; but anal itching is common

Meduzoan

scyphozoans (jellies) cubozoans( box jellies) hydrozoans Most hydrozoans alternate between polyp and medusa forms Hydra, a freshwater cnidarian, exists only in polyp form and reproduces by budding most acyphozoans and cubozoans ( highly toxic ----- Australian sea wasp) spend the majority of their life cycles in the medusa stage

Lophotrozoa

some develop lophophore for feeding, others pass through a trochophore larval stage, and a few have neither feature

Brachipods

superficially resemble clams and other hinge-shelled molluscs, but the two halves of the shell are dorsal and ventral rather than lateral as in clams Brachiopods are marine, and most attach to the seafloor by a stalk Most species in the phylum are extinct and fossil record from paleozoic and mesozoic is rich

spongocoel

the central cavity of an sponge

Phylum Nematoda (roundworms) Tubatrix aceti

vinegar eel Live in acidic oceans and lakes Harmless; feed on bacteria Usually cultured as fish food