chapter 34
sensory setae
hairlike structures that are widely distributed over the body. sensitive to mechanical and chemical stimulation and are linked to nerve cells. abundant on the antennae and legs, the parers of the insect most likely to come into contact with other objects
deep-sea squids
harbor symbiotic luminescent bacteria. may be emitted with the ink to produce a glimmering cloud or they may inhabit cells like chromatophores so they can light up the surface of the animal
many marine mollusks have ? fertilization
external gametes are released by males and females into the water where fertilization occurs.
torsion is a unique characteristic of the
gastropods
in aquatic mollusks internal organs are
gills
excretory system of annelids
has ciliated, funnel-shaped nephridia. each segment has a pair of nephridia that collect wastes and transport them out of the body by excretory tubes.
red-water fever/texas fever
important tick-borne protozoan disease of cattle, horses, sheep, and dogs
tracheoles
in direct contact with individual cells, allowing oxygen and carbon dioxide to diffuse across the plasma membranes.
arthropods originated
in oceans
hemocoel
includes several sinuses and a network of vessels in the gills
nematodes once were thought to be closely related to rotifers due to the presences of a pseudocoelom, but are now considered closer to the arthropods due to
molting
parts of the digestive tract in annelids
pharynx, esophagus, crop, gizzard, intestine ; each specialized for a different function
stylets
piercing organs near the mouth of a nematode
pedipalps
resemble legs but have one fewer segment and are not used for locomotion.
most octopi and squids are capable of changing
skin color and texture to match their background or to communicate with one another. they do so using chromatophores
meat that is cooked "rare" infects humans by?
tapeworms getting into the cattle (1% of cattle in US are infected) and when we eat the infected beef, we will have a parasite
individual bryozoan is called a
zooid
examples of decapods are
lobsters and crayfish
among the lophotrochozoans with a trochophore are phyla
mollusca and annelida
ecdysis
molting
exhalant siphon
water exits through here taking wastes and gametes with it
neodermata: parasitic flatworms
"new skin all neodermatans lvd as ectoparasites on or endoparasites in the bodies of other animals for some period of their lives neodermis is resistant to the digestive enzymes and immune defenses produced by the animals parasitized by these flatworms lack eyespots
decapoda
"ten footed" because of their five pairs of thoracic appendages. exoskeleton is reinforced with calcium carbonate. cephalothorax is covered by a dorsal shield, or carapace, which arises from the head. the pincers are used in obtaining food (crushing mollusk shells)
sexual dimorphism
"two bodies" tail end of the smaller male is hooked, the female is straight
prosoma
(cephalothorax) head and thorax fuse in many crustaceans and chelicerates
spirilia
- develop as embryos using spiral cleavage. - most live in water and move through it using cilia or contractions of the body musculature - two clades
platyzoans
- most prominent group; flatworms - have a simple body with no circulatory or respiratory system but a complex reproductive system - includes marine and freshwater planarians, parasitic flukes and tapeworms
platyzoans: flatworms
- platyhelminthes - flatworms have incomplete gut ~ 20000 species - ciliated, soft bodied animals are flattened dorsoventrally - their bodies are solid aside from an incomplete digestive cavity - have the most complex life cycles among animals - occur in a wide variety of marine, freshwater, and even most terrestrial habitats - carnivores and scavengers - move around by ciliated epithelial cells (partially concentrated on their ventral surfaces, but have some well-developed musculature) - many species are parasitic
four classes of arthropods
1. chelicerates 2. crustaceans 3. hexapods 4. myriapods a fifth is extinct: trilobites
key adaptations that allow gastropods to colonize the land
1. internal fertilization 2. a foot 3. efficient excretory system that prevents desiccation
annelida is composed or two or three classes
1. polychaetes (polychaeta) 2. earthworms and leeches (clitellata)
four classes of mollusks
1. polylacophore (chitons) 2. gastropoda (limpets, snails, slugs) 3. bivalvia (clams, oysters, scallops) 4. cephalopoda (squids, octopi, cuttlefish, chambered nautilus)
earthworms
100-175 similar segments on the body head is not well differentiated no parapodia "few chaetae" eat their way through soil, ingesting it by a muscular action of their strong pharynx what passes through is deposited outside the opening of its burrow as castings that form irregular mounds. they contribute to loosening, aeration, and enrichment of the soil. have no eyes have light-, chemo-, and touch-sensitive cells at end of body where most likely to encounter light hermaphroditic (have separate sexes but cross-fertilize through mating)
clams, mussels, and cockles (bivalvia)
10000 species mostly marine, some freshwater. more than 500 species are in rivers and lakes of north america
lophotrochozoans; annelids (annelida)
12000 species .5 mm to giant Australian earthworms > 3 m long
an individual fluke may live for
15 to 30 years in the liver
diversity and distribution of rotifers
1800 species. most are in fresh water. some live in soil, mosses and the ocean. lifespan is 1-2 weeks, but some can survive in desiccated, inactive state on the leaves of plants. when it rains, they become active and feed in the film of water that temporarily covers the leaf
filariasis (wuchereria bancrofti)
250 million people infected live in circulatory system. may produce elephantiasis
the heart of most mollusks has ? chambers
3 two collect aerated blood from the gills, one pumps it into the hemocoel
centipede species
3000 known. carnivorous, feed mainly on insects appendages of first trunk segment are modified into a pair of poison fangs. poison can be toxic to humans, and although extremely painful, centipede bites are never fatal.
crustaceans
35,000 species largely marine organisms freshwater: crayfish some crabs and copepods are among the most abundant multicellular organisms on Earth. pillbugs/Isopoda 4500 species, terrestrial some sand fleas or beach fleas are semiterrestrial
parasitic nematodes molt ? times
4
snails and slugs (gastropoda)
40,000 species primarily marine, but has a lot of freshwater species and only terrestrial mollusks. most have a single shell, some have lost their shell. most creep on a foot, but some have it modified for swimming head has a pair of tentacles (serves a chemo-or mechanoreceptor) with eyes at the base. undergo torsion during larval life
earthworm has ? blood vessels on each side that help to move blood from the main dorsal vessel to the ventral vessel
5
beef tapeworms can remain viable for up to
5 months after being shed from the human feces
chelicerata
57,000 species chelicerae anterior appendages. body is divided into two magmata: anterior prosoma, and posterior opisthosoma terrestrial:spiders, mites, ticks, scorpions, daddy long legs freshwater: 4000 known species of mites and one species of spider marine: horseshoe crabs, and sea spiders have pedipalps most chelicerates are carnivorous subsist on liquids, including solid food that they liquefy by injecting with digestive enzymes and then suck up with the muscular pharynx respiratory is by means of tracheae or directly through the body surface.
octopi have ? legs
8
chamber nautilus has ? tentacles
80-90
squids have ? legs
8; two tentacles also
lophotrochozoans; nemerteans (nemertea)
900 species of cylindrical to flattened very long worms most are marine, few live in freshwater and humid terrestrial habitats. many break into pieces when disturbed or handled. difficult to measure because they can stretch.
sporocyst
a baglike structure containing embryonic germ cells
how are pearls formed
a foreign object (sand, etc) becomes lodged between the mantle and the inner shell layer. the mantle coats the object with layer upon layer of nacre to reduce the irritation caused by the object.
the distinguishing feature of the bryozoa and brachiopoda is
a lophophore
what group would a species that does not molt, possesses a coelom and has a trochophore larva belong to?
a lophotrochozoa
basic annelid body plan is
a tube within a tube, the digestive tract -- extending from mouth to anus -- passing through the septa, and suspended within the spacious coelom, which is surrounded by the body wall.
nematode lifestyles
active hunters, preying on protists and other small animals. many are parasites of plants or live in the bodies of larger animals.
nudibranchs (sea slugs)
active predators. get name from gills, which are exposed along dorsal surface. many have chemicals. prey on animals that are avoided by other predators. some have extraordinary abilities to extract the nematocysts undischarged, transfer them through their digestive tract to the surface of their bodies, and use them for their own protection
cercomeromorpha: tapeworms and their relatives
adult tapeworm hangs on the inner wall of its hosts intestine by means of the terminal attachment structure. lacks a digestive cavity and digestive enzymes.
neodermis
animal's outer surface
serial segmentation is a key characteristic of which of the following phyla
annelida
blood-sucking leeches secrete
anticoagulant into the wound to prevent blood clots and vasodilators to keep the blood flowing
lobsters and crayfish
appendages called swimmerets are along the ventral surface of the abdomen are used in reproduction and swimming. at the posterior end of the abdomen, paired flattened appendages known as uropods form a kind of paddle between which is a telson
excretory system in arthropods
aquatic: waste may diffuse from blood in the gills fluid passes through the walls of the malpighian tubules to and from the blood in which the tubules are bathed. nitrogenous wastes are precipitated as concentrated uric acid or guanine, are emptied into the hindgut, and eliminated. most of the water and salts in the fluid are reabsorbed by the hind gut and rectum to be returned to the arthropods body.
deep-sea tube worms (riftia)
are gutless as adults. projections from the body of these worms house sulfur-oxidizing bacteria that synthesize organic compounds used by the worm. they aggregate near hydrothermal vents where sulfur is plentiful and can grow to more than a meter in length
ticks
are parasites that attach to the surface of humans and other animals, causing discomfort by sucking blood. can carry disease-causing agents
in terms of numbers of species, the most successful phylum on the planet is
arthropoda
ecdysozoa contains
arthropods and nematodes (tons and tons of animals in each phyla)
sessile crustaceans: barnacles (cirripedia)
at the end of its larval life, a barnacle nauplius attaches by its head to a piling, rock, or other submerge object, metamorphoses, grows calcareous plates around it, and spends the rest of its life capturing food with its jointed, feathery legs.
leech with suckers on both ends moves by
attaching first one and then the other end to the substrate, looping along
scolex
attachment structure in tapeworms
parapodia
bear chaetae. used in swimming, burrowing, or crawling and those of polychaetes that live in burrows or tubes may have chaetae with hooks that help anchor the worm. increase the surface area of the body= important for gas exchange
anterior prosoma in chelicerata
bears all the appendages
most adult gastropods are NOT
bilaterally symmetrical
nematode structure
bilaterally symmetrical unsegmented worms covered by a flexible, thick cuticle that is molted as they grow lack specialized respiratory organs
mollusks are
bilaterally symmetrical but it is modified during the development of gastropods
rotifers (rotifera)
bilaterally symmetrical, unsegmented pseudocoelomates, spiralian platyzoa
mandibles
biting jaws
in an open circulatory system in mollusks
blood (hemolymph) is propelled by a heart through the aorta vessel that empties into the hemocoel. then it moves through the hemocoel being recaptured by other vessels before reentering the heart
schistosomes live in
blood vessels associated with the intestine or the urinary bladder (depending on the species)
centipedes and millipedes (myriapoda)
body of both consists of head region posterior to which are numerous segments.
Schistosomes fertilized eggs must
break through the wall of the blood vessel to get into the intestine or urinary bladder, from which it can exit the body.
chaetae
bristles of chitin on each segment of annelids.
two spiders that can be fatal to humans
brown recluse and black widow
two phyla of mostly marine animals
bryozoa and brachiopoda; characterized by a lophophore
some clam species and file clams can move
by clapping their shells rapidly together (but can't control direction of movement). the adductor muscle that allows this clapping is the part of the scallop eaten by humans.
how do leeches detect prey
by sending gradients of carbon dioxide in the environment
mollusk shells have two layers of
calcium carbonate
zooid
can divide or bud to create asexually another zooid beside the existing one so one wall of the new zooid's zoecium is shared with that of the existing one; constituting a colony
a closed circulatory system in an annelid
carries blood the length of the animal, anteriorly in the dorsal vessel and posteriorly in the ventral one. connections from the ventral to dorsal vessel in each segment bring the blood near enough to each cell so oxygen and food molecules diffuse from the blood into the cells of the body wall and carbon dioxide and other wastes diffuse from the cells into blood.
lyme disease
cause by spirochaetes
rocky mountain spotted fever
caused by bacteria
which is most closely related to lobsters and what characteristics are significant in determining this relationship
centipedes: lobsters, centipedes, and nematodes are all ecdysozoans, but centipedes and lobsters have segmented bodies with appendages, which makes them more closely related
intelligence and complex behaviors are characteristics of the
cephalopods
nauplius larva
characteristic of crustacea providing evidence that all members descended from a diverse group
mouthparts of chlicerates
chelicerae (pincers)
spiders, mites, ticks, and horseshoes crabs are apart of what class
chelicerata
what classes of arthropods posses chelicerae
chelicerata
how do individuals in the colony communicate
chemically through pores between the zoecia
trochophore swims by ?
cilia that encircle the middle of its body
miracidium
ciliated first-stage larva
polychaetes (polychaeta)
clamworms, scaleworms, lugworms, sea mice, tube worms, etc. crucial part of many marine food chains and are very abundant in particular habitats. on most segments, it has a paired, fleshy, paddle-like lateral projections (parapodia) "many chaetae" can swim or crawl. some live in tubes or burrows of hardened mud, sand, mucus-like secretions, or calcium carbonate. have gonads in most segments, but in some, gonads are confined to certain segments.
what characteristic is not found in the arthropods
closed circulatory system
annelids have a ? circulatory system
closed. exchange oxygen and carbon dioxides with the environment through their body surfaces. gas are distributed throughout the body in blood vessels
internal organs of mollusks
coelom is limited to small spaces around the excretory organs, heart, and part of the intestine. the digestive, excretory, and reproductive organs are concentrated in a visceral mass
nephrostome
coiled tube running from the bladder, then connects to an excretory pore
hookworms (necator)
common in southern states. suck blood through the intestinal wall can produce anemia
rotifers have ?
complex bodies with three cell layers, highly developed internal organs, and a complete gut. has a rigid external covering, but the body can lengthen and shorten because the posterior part is tapered so it can fold up like a telescope. many have adhesive toes for clinging to vegetation and other objecys
exoskeleton on arthropods
confers protection against predators, acts like a straight-jacket, restricting motion
wings of insects
consist of chitin and protein, arise as saclike outgrowths of the body wall. generally one or two pairs of wings, not homologous to the other appendages, attach to the middle and posterior segments of the thorax. veins strengthen the wings.
outer shell layer of mollusks
consists of densely packed crystals.
thorax of insect
consists of three segments, each with a pair of legs (6 legs) almost entirely filled with muscles that operate the legs and wings
corona in rotifers
conspicuous ring of cilia at the anterior end "wheel animal"
blood of the closed circulatory system of cephalopods is
contained in a continuous system of vessels. does not contact other tissues directly
ecdysozoa
contains animals that molt when an animal grows large enough that it completely fills its hard external skeleton, it must lose that skeleton by molting while the animal grows, forms a new exoskeleton underneath the existing one upon molting that skeleton, the animal inflate the soft, new one, expanding it using body fluids (air sometimes also) when the new one hardens, it's larger than the molted one was and has room for growth. cicadas molt
ink sac of cephalopods
contains purplish fluid. can eject its contents through the siphon as a cloud that may hide it and confuse predators
posterior opisthosoma in chelicerata
contains the reproductive organs
how are proglottids formed
continuously in a growth zone at the base of the neck, with maturing ones being pushed posteriorly as new ones are formed
annelids move by
contracting their segments. contraction of the circular and longitudinal muscles against the hydrostatic skeleton
in male spiders, the pedipalps are
copulatory organs
wings of moths and butterflies
covered with detachable scales that provide most of their bright colors
the mantle in bivalves
covers the internal surface of the shells, enveloping the visceral mass on its inner side and secreting the shells on its outer side
difference between crabs and lobsters
crab carapace is relatively much broader and the abdomen is just a small vestige tucked under the cephalothorax abdomen of a male crab is much narrower than the female of the same species and size female carried her eggs attached to appendages of the abdomen between it and the thorax
coelomic fluid in annelids
creates a hydrostatic skeleton that gives each segment rigidity (like an inflated balloon)
most hermaphroditic mollusks engage in
cross fertilization; some oysters are able to change sex
crabs, shrimps, lobsters, and pill bugs are apart of what class
crustacea
the ? of a mollusk is a highly efficient respiratory structure
ctenidium
shell-less mollusks
cuttlefish, squids, octopi (cephalopods) slugs (gastropods)
slug and snails are pests how
damage flowers, vegetable gardens, and crops
shrimps, lobsters, crabs, and crayfish are
decapoda
trochophores in marine snails and bivalves
develop into a second free-swimming stage (veliger)
some clams can ?
dig into sand or mud very rapidly by means of muscular contractions of their foot
internal organization of insects
digestive tract is a tube about the same length as the body. insects that feed on juices have sucking mouthparts (leaf hoppers, cicadas, many flies) the coiled digestive tube may be several times longer than the body. digestion takes place primarily in the stomach or midgut, and excretion takes place through malpighian tubules. digestive enzymes are mainly secreted from the cells that line the midgut, but some are contributed by the salivary glands near the mouth in winged insects, tracheae are dilated in various parts of the body, forming air sacs that are surrounded by muscles to form a kind of bellows system that forces air deep into the body
by extending the chateau in some segments so they protrude into the substrate and retracting them in other segments, the worm can do what?
extend its body, but not slip
nervous system in arthropods
double chain of segmented ganglia along the animal's ventral surface. at anterior end, there three fused pairs of dorsal ganglia which constitute the brain. ventral tangle control much of the animal's activities (can carry out eating, moving, and copulating even if brain is gone) brain is a control point or inhibitor (not a stimulator)
predatory gastropods use the radula for what
drill through clam shells so the snail can eat the clams.
ommatidia
each covered with a lens and including a complex of eight retinular cells and a light-sensitive central core, the rhabdom
hermaphroditic
each individual containing both male and female sexual structures
bivalves that live deep in mud or rock the siphons allow them to ?
eat and breathe, functioning like snorkels
redia
elongated, non ciliated larva
chromatophores
epithelial cells that contain pigments
ancestors of springtails and silverfish
evolved before wings did, so they safe considered primarily wingless
how do nematodes respire
exchange oxygen and carbon dioxide through their cuticles. muscles beneath the epidermis, which underlies the cuticle, extend longitudinally, from anterior to posterior. lack circular musculature, so they can shorten but not change diameter the pulling of the muscles against the cuticle and pseudocoelom produces the wriggling motion
chitons (polyplacophora)
exclusively marine 1000 species oval body is covered dorsally with 8 overlapping dorsal calcareous plates. non segmented body, but do have 8 sets of dorsoventral pedal retractor muscles and serially repeated gills. the broad, flat, ventral foot (animal creeps on this) is surrounded by a groove, the mantle cavity, in which the gills are suspended. most are grazing herbivores and live in shallow marine habitats occur to depths of more than 7000 m
sensory receptors in insects
eyes. sensory setae, sound is detected by a tympanum for grasshoppers, crickets, cicadas, and some moths. in other insects sound is detected by sensory hairs. most communicate by means of chemicals known as pheromones.
lophophore
feeding structure, a horseshoe-shaped crown of ciliated tentacles around the mouth used in filter-feeding the coelom extends functions as a surface for gas exchange cilia serve to guide the organic detritus and plankton on which the animal feeds to the mouth
in both centipedes and millipedes
fertilization is internal, and all lay eggs. young millipedes usually hatch with three pairs of legs; they add segments and legs as they pass through growth stages, but they don't change in general appearance. centipedes have several types of development, young of some hatching with their final number of legs and others adding legs after bathing.
which nematode causes disease
filarial worms, pinworms, and trichina worms
the most terminal proglottid is
filled with embryonated eggs. it breaks off or ruptures and the embryos are surrounded by a shell, are carried out with the hosts feces OR the entire proglottid is carried out, where the embryos emerge from it through a pore or the ruptured body wall.
the gills of most bivalves
filter out food. the outlets from the excretory, reproductive, and digestive organs open into the mantle cavity, wastes and gametes are carried away from the mollusk's body with the exiting water stream
book gills
flaps under the prosoma that appear to have evolved from legs
flame cells
flickering movements of the flagella beating inside them
blood flow of nemerteans
flows entirely in vessels that are derived from the coelom.
mollusks are important source of
food. also used for jewelry (pearls), and decorative objects
scolex of many species bears what?
four suckers (and may have hooks)
trochophore
free-swimming/living larva
chelicerae
function as fangs or pincers
in most mites, the cephalothorax and abdomen are ?
fused into an unsegmented, ovoid body.
nauplius
hatches with three pairs of appendages and undergoes metamorphosis through several stages before reaching maturity. in many groups, this stage is passed in the egg, and the hatchling resembles a mini adult
excretion and osmoregulation in flatworms
have an excretory system consisting of fine tubules that run throughout the body. flame cells located on the side branches of the tubules flagella in the flame cells move water and excretory substances into the tubules and then to ores located between the epidermal cells through which the liquid is expelled flame cells mostly regulate water balance of the organism excretory function is secondary to flame cells a lot of the waste diffuses into the gut and is eliminated through the mouth
cephalopods
have largest brain sizes among invertebrates and highly developed nervous systems. many have complex patterns of behavior and very smart. lack external shell. (allows for more movement) water in pumped in by muscles and exits through a siphon, allowing the animal to move by jet propulsion and can be directed to steer. have direct development, oak a larval stage, hatching as mini adults
digestion in flatworms
have only a single opening for their digestive cavity, a mouth located on the bottom side of the animal at mid body - ingests its food and tears it in small bits using muscular contractions in the upper end of the guy (pharynx) - lack circulatory system for the transport of oxygen and food molecules - thin body allows gas to diffuse between its cells and the surrounding environment - branches of the gut extend through the body, so the gut functions in both digestion and distribution of food - cells that line the gut engulf most of the food particles by phagocytosis - some particles are digested externally tapeworms for example, have a mouth at the front of their body and no digestive cavity, they absorb food directly through the body wall
sessile barnacles
have shell-like exoskeleton. had been thought to be related to mollusks until they were discovered to have a nauplius larva.
barnacles
have the longest penis in the animal kingdom, relative to their size, which, considering that they can't move, is useful for mating with other barnacles located the same distance away
scolex is not a
head (has neither concentrated nervous tissue or a mouth)
annelid body plan is composed of ringlike segments
head (has well-developed) cerebral ganglion, or brain, and sensory organs occurs are the anterior end of a series of ringlike segments that resemble a stack of coins. eyes (have lenses and retinas)
in embryonic development of worms, what forms first
head and tail, and then segments form between them
millipede species
herbivores, feed mainly on decaying vegetation like leaf litter and rotting logs (typical habitats for the animals) can roll their bodies into a flat coil or sphere to defend themselves. more than 12,000 species (no more than 1/6 of the number of species that exists)
mites are
herbivorous
flatworm reproduction
hermaphroditic copulation is required between two individuals, and fertilization is internal, each partner depositing sperm in the copulatory sac of the other sperms travels along special tubes to reach the eggs in most freshwater flatworms, fertilized eggs are laid in cocoons strung in ribbons and hatch into mini adults in some marine species, they develop indirectly, the fertilized egg undergoing spiral cleavage, and the embryo giving rise to a larva that swims/drifts until metamorphosing, when it settles in an appropriate habitat
each proglottid is a complete ?
hermaphroditic unit (both male and female reproductive organs)
shell forms
hydrostatic skeleton
development in nematodes
indirect (egg hatches into a larva, which does not grow directly into an adult. must pass through several molts and transfer from one host to another
pinworms (enterobius vermicularis)
infect about 30% of children 16% of adults adult pinworms live in human rectum where they cause itching of the anus. large numbers can lead to prolapse of the rectum. easily killed by drugs
intestinal roundworm (ascaris lumbricoides)
infects ~ 1/6 of people rare in areas with modern plumbing adult female can release as many as 20000 fertilized eggs each day into the gut of its host. eggs are carried from the body in the host's feces and can remain viable for years in the soil. dust can carry them on food, eating lips. once ingested, eggs hatch. the larva flows a circuitous path through the body, and metamorphoses into an adult, which live in human intestine
most gastropods have ? fertilization
internal male inserts sperm directly into the female's body
metamorphosis of a trochophore
involves differentiation of a head and tail end, with development of segments in between, from a posterior growth zone
torsion
involves twisting of the body so the mantle cavity and anus are moved from a posterior location to the front of the body; essentially so the snail doesn't poop in it's shell and die
what is found in the arthropods
jointed appendages, segmentation, and segmented ganglia
lophophorates: brachipods (brachipoda)
lamp shells resemble clams because they have two calcified valves valves are dorsal and ventral many attach to rocks or sand by the pedicle (stalk) that protrudes through an opening in one shell in others, one valve is cemented to the substrate and the animal lacks a pedicle gut is U-shape but some has no anus at all 300 species used as index fossils
in scorpions, the pedipalps are
large pincers
if a beef tapeworm is ingested by cattle what happens?
larva burrows through the intestine wall, reaching muscle tissue through blood or lymph vessels.
mosquitoes and flies
legs are absent in the larvae of certain groups
large adductor muscles in bivalves function
link the shells internally and when they contract, they counteract the hinge ligament to draw the shells together.
spiracles on insects
located on or between the segments along the sides of the thorax and abdomen. can be opened by muscular action. in some parasitic and aquatic groups, the spiracles are permanently closed and the tracheae are just below the surface of the insect and gas exchange takes place by diffusion
proboscis
long muscular tube that can be thrust out quickly from a sheath to capture animal prey
nervous system and sensory organs in flatworms
made of anterior cerebral ganglion and nerve cords that run down the body, with cross-connections that give it a ladder-like shape free-living flatworms are poorly cephalic, with eyespots on their heads these inverted, pigmented cups, which contain light-sensitive cells connected to the nervous system, enable a worm to distinguish light from dark most flatworms move away from strong light
exoskeleton in arthropods
made of chitin and protein. provides antagonism for muscles, support for the body, and protection against physical forces. protests against water loss. the chitin and protein provide a covering that is strong while allowing flexibility in response to the contraction of muscles attached to it. has inherent limitations. as they increase their size, their exoskeletons get disproportionately thick to bear the pull of the muscles. another limitation: b/c body is encased in rigid skeleton, they periodically undergo ecdysis. the anterior and posterior regions of digestive tract and compound eyes are covered with cuticle and also shed ecdysis.
the circulatory system in mollusks
main coelomic cavity is a hemocoel where gas exchange takes place.
jointed appendages in arthropods
maintain protection while providing some flexibility. have developed many efficient modes of locomotion "jointed feet" may be modified into antennae, mouthparts of various kinds, or legs. advantage: extend and retract by bending. joints serve as a fulcrum, or stable point, for appendage movement so leverage is possible.
mouthparts of crustaceans, hexapods, myriapods
mandibles
mollusk body includes
mantle, foot, head
nematodes
many are microscopic and live in soil. a spadeful of fertile soil may contain a million
segmentation in arthropods
many body segments look alike. in others, segments are specialized into functional groups or tagmata (head, thorax, abdomen of insect) fusion of segments (tagmatization) is of central importance in their evolution segments can be distinguished during larval development, but fusion in development obliterates them. all have a distinct head.
crustacean reproduction
many kinds of copulation occurs and the members of some groups carry their eggs (singly or in pouches) until they hatch. develop through nauplius stage.
insect life histories
many undergo metamorphosis. grasshoppers ; immature individuals are quite similar to adults, a series of molts results in an individual getting bigger and more developed; >> simple metamorphosis moths and butterflies ; wormlike larval stage, a resting stage called a pupa or chrysalis, during which metamorphosis occurs, then a final molt into the adult form or imago >> complete metamorphosis
exceptions of respiratory system in arthropods
marine arthropods (crustaceans) have gills marine chelicerates (horseshoe crabs) have book gills some arthropods lack structures for exchanging oxygen, and their outer epithelium or gut have a respiratory function.
caenorhabditis elegans
matures in 3 days. body is transparent. 959 cells. only animal whose complete developmental cellular anatomy is known
head in mollusks
may be well developed or not
sedentary polychaetes
may project feathery tentacles that sweet the water for food, filter feeding; the tentacles may also serve as gills, exchanging gas.
mollusks range in size from
microscopic to huge
part of arthropod success is because of the
modularity of the segmented body, exoskeleton, and jointed appendages
trematoda: the flukes
more than 10000 species attach themselves within the bodies of their hosts with suckers, anchors or hooks. takes in food through its mouth life cycle usually involves two or more hosts first host is almost always a snail, and the final host is almost always a vertebrate getting from one host to another is very risky, and most individuals die in the transition
Lophotrochozoans: mollusks (mollusca)
more than 110,000 species. second in size to arthropods. examples: snails, slug, clams, scallops, oysters, cuttlefish, octopi, squids, etc
octopi, squids, and nautiluses (cephalopoda)
more than 600 species strictly marine active predators that swim only mollusks with closed circulatory system foot has evolved into a series of arms equipped with suction cups, adhesive structures, or hooks that seize prey.
insects (hexapoda)
most abundant animals on earth. live in every habitat on land and in freshwater. very few have invaded the sea. 90,000 species are in the US and Canada.. actual # approaches 125,000. a quintillion individual insects are alive at one time
Acari
most diverse of the chelicerates. 30000 species of mites and ticks have been named. found in nearly every habitat. feed on various organisms as predators and parasites
reproduction in mollusks
most have separate sexes but some are hermaphroditic.
leeches
most live in freshwater, some are marine, and some terrestrial dorsoventrally flattened, 2-6 cm hermaphroditic (clitellum develops only during breeding season) can cross fertilize coelom is reduced and not divided into segments. the suckers are one or both end are used for locomotion and to attach prey capable of swimming no chaetae (except one species) some eat debri/waste/etc or small animals, others suck blood or fluids from hosts.
trichinosis (trichinella)
most serious and common nematode live in small intestine of some mammals (pigs, bears) where fertilized females burrow through the intestinal wall and release live young the young enter the lymph channels, transporting to muscles throughout the body. they mature and form highly resistant, calcified cysts. 20 deaths in the past decade
ecdysozoans: arthropods (arthropoda)
most successful of all animals well over 1,000,000 species 2/3 of animals on earth belong here insects alone are 30 million species small enormous economic importance affecting all aspects of human life pollinate crops, valuable as food for humans and other animals. compete with humans for food and damage crops. insects most important herbivores in terrestrial ecosystem
when a cercariae encounters a fish of the family cyprinidae (carp, goldfish) it bores into the
muscles, loses it's tail, and encysts, transforming into a metacercaria
centipede segments
nearly all have one pair of appendages technically means 100 legs but all centipedes have fewer than 100 legs (15, 21, or 23 pairs of legs)
millipede segments
nearly all have two pairs of appendages. each segment is a simple tame derived evolutionarily from two ancestral segments never reaches 1000 legs, most have 100 or fewer in each, they have a pair of complex glands that produce a bad-smelling fluid, which they exude for defense through openings along the sides of the body. some produce cyanide gas from segments near their head
torsion may lead to the reduction/disappearance of the
nephridium, gonad, or other internal organs on one side
cercaria (plural cercariae)
next larval stage, the tadpole-like
removal of wastes in mollusks
nitrogenous wastes are removed by the nephridium. a typical one has an open funnel (nephrostome) lined with cilia. a coiled tube runs from the nephrostome into a bladder, connecting to an excretory pore. Wastes are gathered by the nephridia from the coelomic cavity and discharged into the mantle cavity. Sugars, salts, water, and other materials are reabsorbed by the walls of the nephridia and returned to the body as needed to maintain water balance
are all zoecia identical?
no some are specialized for functions such as feeding, reproduction, or defense
are leeches usually noticed right away?
no, they inject anesthetics into the prey to prevent being noticed while piercing the skin. usually detected after detaching
turbellaria; free-living flatworms
not monophyletic so it is likely to be divided into several classes. one of most familiar members is freshwater members of the genus Dugesia, the common planarian used in bio labs
ocelli
occur in some arthropods with compound eyes. distinguish light from darkness.
malpighian tubules
occur in terrestrial insects, myriapods, and chelicerates. slender projections from the digestive tract attached at the junction of the midgut and hind gut
beef tapeworm (taenia saginata)
occurs as a juvenile in the inter muscular tissue of cattle. as an adult, it inhabits the intestines of humans beings, where a mature worm may each to 10 m or more.
simple eyes are also called
ocelli
compound eyes are composed of hundred or more independent visual unites called
ommatidia
arthropods colonized
on land
all mollusks except cephalopods have an ? circulatory system
open
hemocoel
open circulatory space
circulatory system in arthropods
open. longitudinal muscular vessel called the heart, near dorsal surface of thorax and abdomen. when heart contracts, blood is pumped anteriorly. then flows through open spaces between tissues toward posterior end. when heart relaxes, blood returns to it from spaces through one-way valves in the posterior region of the heart
spiracles
openings in the exoskeleton that can be opened and closed by valves. prevent water loss by closing them
flukes that cause disease in humans
oriental liver fluke (clonorchis sinensis) cercariae flukes of the genus schistosoma
in the flatworm, flame cells are involved in what metabolic process?
osmoregulation
each segment in an annelid has a
pair of excretory organs, ganglion, and locomotory structure in most marine annelids, each also has a set of reproductive organs
flatworms consist of two major groups
parasitic and free-living
worm pentastomids
parasitize the respiratory tracts of vertebrates crustaceans
oriental liver fluke
parasitizes humans, cats, dogs and pigs. lives in the bile duct of the liver. common in asia. 1-2 cm long. fertilized egg containing a ciliated first-stage larva, the miracidium, is passed in the feces. if the larva reaches water, it may be ingested by an aquatic snail, but most do not reach water and most that do are not ingested. the prodigious number of eggs a parasitic flatworm produces is an adaptation to this life cycle full of risks. within the snail, the ciliated larva transforms into a sporocysts which develops into a redia. each of these larvae grows within the snail, then gives rise to several individuals of the next larval stage, the tadpole-like cercaria
mites
pass through several stages during they rife cycle
inner shell layer of mollusks
pearly in appearance and called "mother-of-pearl/nacre"
largest known nematode parasitizes what animal
placenta of sperm whales
two clades of spirilians
platyzoans and lophotrochozoans
all spiders have
poison glands with channels through their chelicerae, which are pointed and are used to bite and paralyze prey
spiders play a major role in almost all terrestrial ecosystems how?
predators of insects and other small animals. hunt their prey or catch it in silk webs of remarkable diversity. silk is formed from a fluid protein that is forced out of spinnerets on the posterior portion of the spiders abdomen. trap-door spiders construct silk-lined burrows with lids, seizing their prey as it passes by. wolf spiders and tarantulas hunt rather than spin webs
external features of insects
primarily terrestrial. mouthparts have the same basic structures: modifications reflect feeding habits. most have compound eyes and many have ocelli
foot in mollusks
primary means of locomotion (except cephalopods >> squids, octopi, chambered nautilus)
the gonads in the proglottis do what
progressively mature away from the neck, fertilization occurs, and the embryos form
gills in mollusks
project into the mantle cavity. consist of filaments rich in blood vessels that increase the surface area and capacity for gas exchange. continuous stream of water that passes through the mantle cavity, propelled by cilia on the gills carries oxygen in and carbon dioxide away. so efficient that they can extract 50% or more of the dissolved oxygen from the water that passes through.
some polychaete worms have
protonephridia like flame cells of planarians
leeches pharynx
pumps the blood out quickly once a hole has been opened
posterior end of the worm
pygidium
feeding a prey capture of mollusks
radula consists of dozens to hundred of microscopic, chitinous teeth arranged in rows on an underlying membrane and lies in a chamber at the anterior end of the gut. membrane wraps around a muscular support structure so the radula can be protruded through the mouth and move something over what is being rasped.
cone snails
radula is transformed into a harpoon to capture prey and some can even kill humans
bivalves are the only mollusks that don't have a
radula. their gills are adapted to filter food particles from the water. primitive bivalves pick up bits of food from soft sediments using appendages around the mouth
radula
rasping, tonguelike structure used in feeding for mollusks
zebra mussel are pests how
recently invaded many North American freshwater ecosystems
flatworms are known for their
regenerative capacity; when a single individual of some species is divided into two or more parts, an entirely new flatworm can regrow what is missing from each bit
freshwater parasitic leeches
remain on hosts for long periods of time, sucking their blood from time to time.
foot for bivalves
wedge-shaped adapted for burrowing or anchoring the animal in its burrow.
nemertean body plan
resembles flatworm with networks of fine tubules constituting the excretory system and with internal organs not lying in a body cavity. a bit of cephalization is present, with two lateral nerve cords extending posteriorly from an anterior ganglion. some have eyespots on the head. has a complete gut (mouth and anus connected by a straight tube)
nemerteans have a fluid cavity called
rhynchocoel
rhynchocoel
sac that serves as a hydraulic power source for the proboscis
embryos of tapeworms are
scattered in the environment, on leaves, in water, or in other places where they may be picked up by other animals
most important trematodes to human health are blood flukes of the genus
schistosoma
about 800,000 people die each year from the disease called
schistosomiasis (or bilharzia)
tapeworms are divided into three zones
scolex, proglottids, neck
veliger
second free-swimming stage
fleas and lice are considered
secondarily wingless, having descended from ancestors with wings
shells of mollusks
secreted by the outer surface of the mantle. protects against predators and adverse environmental conditions. not essential.
phoronid
secretes a chitinous tube around itself from which it can extend its lophophore to feed. quickly withdraws into the tube when disturbed. 10 species some live buried in sand some are attached to rocks (singly or in groups) forming loose colonies
salivary gland of cephalopods
secretes a toxin that can be injected into prey; the tiny blue-ringed octopus of Australia can kill a human with its deadly bite
clitellum in earthworms
secretes mucus that holds the worms together during copulation, their anterior ends pointing in opposite directions, their ventral surfaces touching.
annelids
segmented coelomate worms, the most familiar of which is the earthworm, but also leeches and largely marine polychaetes
palolo worms (palola vidiris)
segments are found at the end of the body; spawning involves the end of the worm breaking off and swimming to the surface of the sea, where it ruptures, releasing the gametes. the gamete-filled terminal parts of palolo worms are considered delicacies by some in the south pacific
in most chelicerates, the pedipalps are
sensorial, acting like the antennae of other arthropods
pheromones
sent forth to into the environment, where they convey a variety of messages, including mating signals and trail markers
internally, segments are divided from one another by
septa
book lungs
series of leaflike plates within a chamber into which air is drawn and from which it is expelled by muscular contraction
proglottids
series of repetitive structures in tapeworms
lophophorate animals are
sessile (anchored in place, don't move)
respiratory structures in bivalves
set of complexly folded gills on each side of the visceral mass, lie in the mantle cavity. edges may be partly fused.
reproduction in nematodes
sexual males and females differ in form (sexual dimorphism) fertilization is internal. male uses hooked end and associated structure to help inseminate the female.
nemerteans have ? reproduction
sexual; some are capable of asexual reproduction by fragmentation but usually results in death
bivalves are pests how
ship-worms burrow through wood exposed to the sea, damaging boats, docks, and pilings
lophophorates: bryozoans (bryozoa)
small live in colonies that look like patches of moss on the surfaces of submerged objects "moss animals" digestive system is U-shape, with the anus opening near the mouth, as in many sessile animals 4000 species both marine and freshwater each zooid secretes a tiny chitinous chamber (zoecium)
respiratory in most terrestrial arthropods
small, branched, cuticle-lined ducts (tracheae) tracheae branch into small tracheoles insects depend on respiratory system to carry oxygen to their tissues, so all parts of the body must be a respiratory passage. limitations on arthropods size:air passes into tracheae through spiracles. many spiders have book lungs
cephalopod getting prey
snares it with arms, bites it with strong beaklike jaws, pulls it into mouth by the action of the radula.
brachiopods and phoronids are
solitary lophophorates
adults of nematodes
some species consist of a fixed number of cells (eutely) because of this, nematodes are extremely important for genetic and developmental studies
earthworms and leeches (clitellata)
some think earthworms belong to oligochaeta and leeches to class hirudinea. now it is one class (clitellata)
nephridium
sort of a kidney in a mollusk
male mosquitoes use thousands of sensory hairs on their antennae to detect
sounds made by the vibrating wings of female mosquitoes
reproduction in earthworms
sperm cells are released from pores in specialized segments of one partner into the sperm receptacles of the other, the process going in both directions simultaneously. a few days after worms separate, the clitellum of each worm secretes a mucus cocoon, surrounded by a protective layer of chitin. as the worm moves, this sheath passes over the female pores of the body, receiving eggs and incorporating the deposited sperm so that fertilization takes place with the cocoon. when the cocoon passes over the end of the worm, its edges pinch together. in the cocoon, the fertilized egg develop directly into young worms that are similar to the adults
mollusk zygote undergoes
spiral cleavage embryo develops into a free-swimming larva (trochophore) that resembles the larval stage of many marine annelids
fertilization in annelids results in
spiral cleavage followed by the production of ciliated, mobile trochophore larvae (similar to mollusks)
coiling
spiral winding of the shell (also occurs in cephalopods)
Protostomes clades
spirilia ecdysozoa
chambered nautilus lack
suckers
telson
tail spine
centipedes that do onto add legs as they grow tend to ?
take care of their young, a behavior rather uncommon among invertebrates
projecting from the edge of a scallops mantle are
tentacle-like projections having complex eyes between them
veliger forms
the beginnings of a foot, shell, and mantle
advantage of segmented body plan
the development and function of individual segments or groups of segments can differ (some segments may be specialized for reproduction, but other are adapted for locomotion or excretion)
a ventral nerve cord connects
the ganglia in each segment with one another and with the brain. these neutral connections allow the worm to function as a unified and coordinated organism
elephantiasis
the lower extremities may sweep to disfiguring proportions. occurs because worms clog lymph nodes, cause severe inflammation and resulting in sweeping by preventing the lymph from circulating. larval filiarial worms are transmitted by intermediate host (typically mosquito)
in terrestrial gastropods
the mantle cavity (as gills inside) is extremely rich in blood vessels and serves as a lung. the lung absorbs oxygen from the air much more effectively than a gill could but a snail will drown if its lungs fill with water. for this reason, they can close the opening of the lung to the outside
mollusks evolved in
the oceans, and most have remained there
what happen when circular muscles are contracted around a segment (in annelids)
the segment decreases in diameter, so the coelomic fluid causes the segment to elongate.
what happens when longitudinal muscles contract (in annelids)
the segment shortens, so the coelomic fluid causes the segment to increase in diameter.
when a lobster or crayfish contracts its abdomen muscle what happens
the uropods rapidly and forcefully backward through the water. it is this very large muscle that constitutes the "lobster tail" so valued by human dinners
schistosomiasis
the worms protect themselves from the body's immune system in part by coating themselves with some of the host's own antigens that effectively render the worm immunologically invisible
alternating the circular and longitudinal contractions in annelids allows what
the worms to move in complex ways
mantle in mollusks
thick epidermal sheet, covering the dorsal (top) side of the body and bounds the mantle cavity. secretes the calcium carbonate of the shell
tympanum
thin membrane associated with the tracheal air sacs.
if a worm is cut in pieces what happens
those parts containing the head or tail can regenerate the missing parts, but the parts coming from the middle die
hermaphroditic state of barnacles
thought to be related to their sessility.
insect body
three regions: head, thorax, and abdomen.
nematodes digestive system
well-developed. feed on a diversity of food sources. near the mouth (anterior end) theres hairlike sensory structures mouth may equipped with stylets food passes into the mouth from the sucking action by the rhythmic contraction of a muscular pharynx and continues through the intestine; waste is eliminate through the anus
crustacean body plans
three tagmata: anteriormost two (cephalon and thorax) may fuse to form the cephalothorax most have two pairs of antennae, three pairs of appendages for chewing and manipulating food, various pairs of legs. appendages are biramous "two-branched" resemble myriapods with their appendages on their abdomen as well as their thorax. only arthropods with two pairs of antennae large crustaceans have feathery gills for respiration near the bases of their legs. oxygen extracted from the gills is distributed through the circulatory system. in smaller crustaceans, gas exchange takes place directly through the thinner areas of the cuticle or the entire body
zoecium
tiny chitinous chamber that is attached to rocks or other substrates such as the leaves of marine plants and algae. calcium carbonate is deposited in the wall
benthic mollusks use their radula for what
to scrape up algae and other food materials
leeches were used in medicine for what reason
to treat patients whose diseases were mistakenly believed to be caused by an excess of blood.
gastropods undergo
torsion
neodermata contains two subgroups
trematoda and cercomeromorpha
lophotrochozoa has two major phyla
trochophore and lophophore
siphons
tubes
torsion
twisting of the body
bivalves have
two shells that are hinged dorsally so the shells are oriented laterally. a ligament lays on the hinge is structured to cause the shells to open.
mollusks
unsegmented, and their coelom is reduced to a hemocoel and some other small body spaces includes animals as diverse as octopuses, snails and clams.
food gathering of rotifers
use corona to beat cilia to make it appear that the wheel is rotating around the head of the animal. used for locomotion, but the cilia sweets food in the rotifers mouths. once food is swallowed, it's crushed with a complex jaw in the pharynx
how are leeches used in medicine today
used to remove excess blood after surgery or to keep blood from coagulating in severed appendages that have been reattached
polychaete gametes
usually are released into the water, where fertilization occurs externally.
ecdysocoans: roundworms (nematoda)
vinegar eels, eelworms 20000 species (actual # might approach 100X that) marine and freshwater parasites of plants and animals
inhalant siphon
water enters the mantle through here bringing oxygen and food