chapter 33

Question 1

What 2 phyla belong to the lophophorates? Structure and function of lophophores?

Answer 1

Bryozoa and brachiopoda. Both groups have a lophophore which is a U shaped ridge around mouth bearing ciliated tentacles, used for gas exchange and guiding food to mouth.

Question 2

characteristics of bryozoans

Answer 2

they’re exclusively colonial animals. Very small animals known as “moss animals”. Both marine and freshwater form. U shaped digestive system with anus outside ring of lophophore

Question 3

Characteristics of brachiopods (lampshells)

Answer 3

look like clams but are not. dorsal is back side. ventral is belly side. They are deuterostomes, attach to rocks by pedicel or one shell vavle, lophophore located between shells, u shaped gut in some others have no anus

Question 4

Characteristics of phoronid tube worms

Answer 4

protostomes!, worm secreres chitinous tube, withdraws into tube when disturbed, some buried in sand; others attached to rocks

Question 5

examples of mollusks? what type of habitats do they occupy?

Answer 5

snails, slugs, clams, octopus, cuttlefish, oysters, mussels, squid etc. occupy every habitat on earth.

Question 6

where did mollusks evolve?

Answer 6

evolved in the ocean; some slugs and snails are adapted to life on land or freshwater

Question 7

size range of mollusks?

Answer 7

few millimeters to a giant squid that could grow to 15 meters and 250 kg

Question 8

examples how mollusks are beneficial to economy. Examples of how mollusks are detrimental to economy.

Answer 8

benefical for food, mother of pearl for jewelry. they can damage boats, docks, pilings, and wood exposed to the sea, zebra mussels invade freshwater ecosystems. Some slugs/snails damage flowers, vegetables and crops, some are intermediate hosts to larval stages of parasites such as flukes

Question 9

symmetry found in mollusks?

Answer 9

bilateral symmetry

Question 10

location/structure and function of mantle, foot, and head of a mollusk

Answer 10

mantle: thick epidermal sheet surrounding the mantle cavity; secretes calcium carbonate shell
foot: primary means of locomotion, can be used for attachment, capturing food and digging
Head: may be well developed or not

Question 11

what organs are contained in the visceral mass

Answer 11

visceral mass contains digestive, excretory, and reproductive organs

Question 12

structure and function of ctenidia

Answer 12

cten(comb) idia(gills) in aquatic mollusks. have much surface area for gas exchange; gills of bivalves also filter out food

Question 13

Composition of a mollusk shell? How are they formed? Do all mollusks have shells?

Answer 13

2 layers of calcium carbonate; inner layer is pearlescent (mother of pearl or nacre); pearls form when a grain of sand or other irritant lodges between inner shell layer and mantle layers of nacre reduce irritation. Some mollusks have reduced, internalized, or no shell at all. Shell is secreted by mantle and protects against predators

Question 14

structure and function of radula. Do all mollusks have a radula?

Answer 14

radula is rasplike structure with rows of chitinous teeth used to scrape food off surfaces. some radular structures are modified for drilling; others work like harpoon along with a venom gland. Bivalves are the only mollusks without a radula.

Question 15

how do mollusks remove nitrogenous wastes?

Answer 15

nephridium removes nitrogenous wastes works somewhat like a kidney. Wastes are dumped into mantle cavity. Sugars, salts, water, and other materials are absorbed by nephridial walls and returned to animal’s body to maintain osmotic balance

Question 16

what type of circulatory system do mollusks have? How many chambers are in a mollusk heart?

Answer 16

open circulatory system with 3 chambers in their hearts

Question 17

what is a hemocoel? what is a hemolymph?

Answer 17

hemocoel is made of several sinuses and vessel network in gills and hemolymph is equivalent of blood

Question 18

are mollusks separate sexes or hermaphroditic?

Answer 18

most have separate sexes, a few bivalves and many freshwater and terrestrial gastropods are hermaphroditic. Some oysters can change sex

Question 19

which mollusks have external fertilization and which mollusks have internal fertilization

Answer 19

marine mollusks have external fertilization
gastropods have internal fertilization

Question 20

what is a trochophore and a veliger?

Answer 20

trochophore is a free swimming larva that is feature of mollusks and marine annelids
Veliger is 2nd free swimming larval stage.

Question 21

major features and unique features of mollusk class polyplacophora: Chitons

Answer 21

marine only, 8 overlapping dorsal plates, body is not segmented, most are grazing herbivores living in shallow marine habitats

Question 22

feautres and unique characteristics of mollusks class Gastropoda: snails and slugs

Answer 22

primarily marine, there are freshwater species also, the only terrestrial mollusks are gastropods. Most gastropods have single shell, but some have lost their shell. Creep on their foot in some foot is modified for swimming. Head has pair of tentacles, eyes located at base of tentacles. Unique feature is torsion which is twisting of body during larval growth so mantle cavity and anus are moved to front of body. Predators.

Question 23

features and characteristics of class Bivalvia mollusks: Mussels, cockles

Answer 23

marine some freshwater, no radula, no head, wedge shaped foot for digging, have 2 shells (valves), inhalant or incurrent siphon is where water enters bringing food and oxygen, exhalant or excurrent siphon is where water exits

Question 24

features and characteristics of class cephalopoda: octopuses, squids, nautiluses

Answer 24

more than 600 species, marine only, very active predators, only mollusks with closed circulatory system, foot evolved into arms with suction cups, adhesive devices and hooks for capturing prey, strong beak like jaws; radula; salivary glands, largest relative brain size; highly developed nervous system, complex behavior patterns, highly intelligent, cephalopod eyes, move by jet propulsion, ink sac

Question 25

what type of organisms belong to phylum nemertean? what habitats are they found?

Answer 25

ribbon worms found in mainly marine, few freshwater or humid terrestrial habitats.

Question 26

basic body plan of a nemertean

Answer 26

resembles plan of a flatworm, some cephalization with 2 lateral nerve cords, complete gut with both mouth and anus

Question 27

what is a rhynchocoel

Answer 27

fluid filled sac that serves as hydraulic power source for proboscis

Question 28

are nemerteans gonochoric or hermaphroditic? how do they reproduce

Answer 28

they are gonochoric (separate sexes) and reproduce by sexual reproduction some asexually by fragmentation

Question 29

phylum annelida includes segmented worms, What is the advantage of segmentation?

Answer 29

development and function of individual segments or groups of segments can differ

Question 30

basic body organization of an annelid worm

Answer 30

ringlike segments. brain or cerebral ganglion and sensory organs at anterior. many have eyes, head and tail develop first then segments form between, segments divided by septa, each segment has pair of excretory organs, a ganglion and locomotory structure. closed circulatory system. ventral nerve contracts

Question 31

how do annelid worms move?

Answer 31

move by contracting circular and longitudinal muscles against the hydrostatic skeleton

Question 32

what are chaetae (setae) and what is their function

Answer 32

bristles made of chitin that help anchor annelid in substrate so they don't slip when they move

Question 33

characteristics of class polychaeta belonging to clade errantia. what are parapodia? how do polychaetes reproduce?

Answer 33

marine worms, gonochoric, parapodia are fleshy paddle like lateral projections used for swimming, burrowing, or crawling. parapodia help gas exchange

Question 34

what 2 groups of organisms belong to class sedentaria? which orgnaisms were formerly described as oligochaetes? which organisms were formerly described as hirudineans?

Answer 34

earthworms and leeches. earthworms were formerly in class oligochaeta and leeches were formerly class hirudinea

Question 35

function of clitellum?

Answer 35

a thickened band on body that secretes mucus to hold worms together during copulation and to form a cocoon for fertilized eggs to develop

Question 36

characteristics of earthworms

Answer 36

head is not well developed, no parapodia, few chaetae and project directly from body wall, eat their way through soil, no eyes, hermaphroditic

Question 37

leech characteristics

Answer 37

most freshwater few marine, dorsoventrally flattened, hermaphroditic, cross-fertilization, clitellum only develops during mating season, coelom reduced and not segmented. no chaetae, some suck blood

Question 38

what fraction of all animals are arthropods?

Answer 38

2/3rds of all animals are arthropods

Question 39

examples (good and bad) of economic importance of arthropods

Answer 39

good: pollinate crops, food for humans and other animals bad: damage crops; insects are voracious herbivores, carriers/spreaders of disease to plants and animals including humans

Question 40

organisms in class chelicerata (arthropods)

Answer 40

spiders, mites, ticks, horseshoe crabs

Question 41

organisms in class crustacea (arthropods)

Answer 41

crabs, shrimp, lobsters, barnacles, pill bugs)

Question 42

organisms in hexapoda (arthropods)

Answer 42

insects

Question 43

organims in myriapoda (arthropods)

Answer 43

centipedes, millipedes

Question 44

organisms in class trilobita

Answer 44

EXTINCT

Question 45

distinguish between chelicerae and mandibles. Which group exhibit one or the other of these?

Answer 45

chelicerae (pincers) in chelicerates, mandibles (biting jaws) in hexapods, crustaceans, and myriapods

Question 46

what is tagmatization? what are 3 tagmata usually seen in arthropods? what is a cephalothorax?

Answer 46

tagmatization= the fusion of segments into specialized functional groups. Three tagmata in arthropods are head, thorax, and abdomen. Cephalothorax is when the head and thorax are fused together.

Question 47

what is an exoskeleton, what is it made of? what are its functions? what limits are placed on organisms that have exoskeletons?

Answer 47

external covering for the body. made of chitin and protein this combination is strong and flexible. provides antagonism for muscles, support for body, protection against physical forces, can protect against water loss. Limitations are size and rigidity. Weight gets too great with increased size, arthropods must undergo ecdysis(shedding) or molting

Question 48

functions of jointed appendages in arthropods?

Answer 48

may be modified into antennae, various kinds of mouthparts and legs. can bend to extend or retract, joints serve as a fulcrum for appendage movement so leverage is possible.

Question 49

what kind of circulatory system do arthropods have? how does it operate?

Answer 49

open circulatory system, heart pumps blood anteriorly; blood flows toward posterior through spaces between tissues; when heart relaxes, blood returns to posterior region of heart through one-way valves

Question 50

typical nervous system of an arthropod

Answer 50

double chain of segmented ganglia along ventral surface, three fused ganglia form brain, functions such as eating, moving, copulating

Question 51

what is ommatidia and ocelli

Answer 51

ommatidia (individual visual units) compund eyes are composed of that ocelli are simple eyes present in some arthropods

Question 52

what are these respiratory structures in arthropods. Gills, book gills, tracheae, spiracles, book lungs

Answer 52

gills- in marine crustaceans book gills- in horseshoe crabs tracheae- in terrestrial arthropods; tracheae branch into tracheoles spiracles- openings in exoskeleton where air enters; they can be closed to prevent water loss book lungs- in many spiders

Question 53

how do marine arthropods get rid of excretory wastes? what are malpighian tubules and what type of arthropods are they found?

Answer 53

waste diffuses from blood in gills. malpighian tubules occur in myriapods, and chelicerates. They are slender projections from digestive tract, attached at junction of midgut and hindgut, tubules contain fluid and nitrogenous wastes from blood that bathes tubules.

Question 54

what kind of organisms are found in class chelicerata? what are the basic characteristics of the chelicerates?

Answer 54

Spiders, mites, ticks, scorpions, daddy long-legs, horseshoe crabs. They have 2 tagmata= anterior prosoma which bears all appendages and opisthosoma which contains reproductive organs. Pair of chelicerae (fangs or pincers) Pair of pedipalps: copulatory organs in male spiders, large pincers in scorpions, sensorial in most other chelicerates, 4 pairs of walking legs, mostly carnivorous but mites are herbivorous

Question 55

what organisms are found in order araneae? what unique features or structures do they possess?

Answer 55

Spiders. Important as predators of insects, produce silk that is forced out of spinnerets, wolf spiders and tarantulas hunt rather than spin webs, all spiders have poison glands with channels through their chelicerae, poison/venom paralyzes prey, bites of black widow and brown recluse can be fatal to humans and mammals.

Question 56

what organisms are found in order Acari? describe how these organisms "make their living"

Answer 56

Mites and Ticks. found in every habitat, predators and parasites of organisms, less than 1 mm long, cephalothorax and abdomen fused into ovoid body, respiration using tracheae or directly through body surface, ticks are blood-sucking parasites of humans and other animals, some ticks carry disease causing agents such as Rocky Mountain spotted fever, Lyme disease, and red water fever (affects cattle, horses, sheep, dogs)

Question 57

what kind of organisms are found in class crustacea? in what habitats are these organisms found?

Answer 57

crabs, shrimps, lobsters, barnacles, pill bugs. about 35,000 species are mainly marine but some crayfish live in freshwater; still others are terrestrial (pill bugs) or semi terrestrial (sand fleas and beach fleas)

Question 58

Typical characteristics of crustacean organisms

Answer 58

3 tagamta= cephalon and thorax and abdomen. Two pairs of antennae (CRUSTACEANS ARE ONLY ARTHROPODS TO HAVE THIS!!) 3 pairs of appendages for chewing and manipulating food, various pairs of legs on abdomen and thorax, crustacean appendages (with possible exception of first pair of antennae) are biramous ("two-branched") large crustaceans have feathery gills for respiration/gas exchange, gas exchange in smaller crustaceans occurs directly through thin regions of cuticle or entire body

Question 59

what is a nauplius larva?

Answer 59

crustaceans begin life as an egg then go through series of larval stages. The First larval stage for them is called nauplius.

Question 60

What are the functions of the following structures found in decapod crustaceans (shrimp, lobsters, crab, crayfish): Pincers, swimmerets, uropods, telson

Answer 60

Pincers: used for obtaining food Swimmerets: on ventral surface of abdomen in lobsters and crayfish used for swimming and reproduction Uropods: paired flattened appendages at posterior that form a paddle, push water anteriorly, propelling animal posteriorly Telson: tail spin

Question 61

characteristics of barnacles with regard to habitat, feeding, and reproduction

Answer 61

Barnacles= sessile crustaceans sessile adults but nauplius larva is mobile, adults are filter-feeders; sweep legs through water in order to gather small food particles, hermaphroditic condition is thought to be related to sessile lifestyle, have longest penis relative to their size, allows sessile animals to cross-fertilize

Question 62

External characteristics of hexapods(insects)?

Answer 62

Primarily terrestrial, size range .1mm to 3cm in length or wingspan, mouthparts modified piercing, sucking, or sopping up liquids. Most have compound eyes some with ocelli, head thorax abdomen, thorax has 3 segments, each segment with a pair of legs, many insects have 1 or 2 pairs of wings, wings are saclike outgrowths of body wall

Question 63

internal organization of hexapods (insects)

Answer 63

digestive tract tube is same length as body, but insects that feed on juices, their digestive system is coiled and may be several times longer than body. digestion occurs in stomach or hindgut, malphigian tubes for excretion, trachea for gas exchange, spiracles are openings between segments along side abdomen and thorax where air enters