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