Crustaceans | Ch20 – Complete Test Bank – 18th Ed

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MULTIPLE CHOICE - Choose the one alternative that best completes the statement or answers the question.
1) How do crustaceans differ from other arthropod groups?

A) Crustaceans possess a telson.
B) Crustaceans have two pairs of antennae.
C) Crustaceans have chitinous exoskeletons.
D) Crustaceans possess a two-part body plan of cephalothorax and abdomen.
E) Crustaceans possess a hemocoel.

2) Crustacea are biramous, meaning they possess

A) a telson.
B) two large pincers.
C) two pair of antennae.
D) jointed appendages having two branches.
E) a body divided into two regions, the cephalothorax and abdomen.

3) The various specialized body structures along the malacostracan body are thought to be derived from a common biramous appendage, which suggests

A) serial homology.
B) telsonization.
C) arthropodization.
D) analogous homology.
E) convergent evolution.

4) The major body space in arthropods is the

A) coelom.
B) pseudocoelom.
C) hemocoel.
D) blastocoel.
E) telson.

5) The tail fan of many malacostracans is

A) the rostrum.
B) the postcarapace.
C) the endopod.
D) a combination of uropods and telson.
E) a fusion of the last biramous appendages.

6) The segments of crustaceans are covered with a dorsal plate that is known as a/an __________ and a ventral plate that is known as a/an __________.

A) epiproct, underproct
B) flexor, extensor
C) endopod, exopod
D) endite, exite
E) tergum, sternum

7) The generalized appendage of a crustacean has a basal portion or protopod that has a lateral __________ and a medial __________.

A) epiproct, underproct
B) flexor, extensor
C) exopod, endopod
D) endite, exite
E) tergum, sternum

8) Medial and lateral processes on a crustacean limb are called __________ and __________ respectively.

A) epiprocts, underprocts
B) flexors, extensors
C) exopods, endopods
D) endites, exites
E) terga, sterna

9) As part of your lab assignment, you are charged with summarizing the characteristics of the appendages of a crayfish. After you observe the appendages, you can conclude that the appendages include

A) two pairs of abdominal swimmerets that are different in males and females.
B) a telson.
C) two large pincers.
D) two branches on all appendages.
E) All of the choices listed are crayfish appendages.

10) The "bailer" of a crayfish that draws water over the gill filaments is a part of the

A) second maxillae.
B) caudal furca.
C) third maxilliped.
D) first walking leg.
E) first swimmeret.

11) Since the hemolymph of crustaceans leaves the heart by arteries, why is it considered an open rather than a closed system?

A) The hemolymph lacks any respiratory pigments.
B) The hemolymph flows through the hemocoel and returns via venous sinuses rather than enclosed veins.
C) The heart does not pump hemolymph but it moves by ciliary action instead.
D) The arteries "dead end" and the hemolymph must backflow through the arteries.
E) The hemolymph lacks any respiratory function.

12) The respiratory apparatus of a crayfish is

A) a set of gills under the carapace.
B) book lungs inside the carapace.
C) a set of gills along the underside of the tail.
D) tracheal tubes throughout the body.
E) a cluster of alveoli under the tail.

13) The first pair of walking legs in a crayfish, lobster, crab, and their relatives, that is enlarged with a terminal claw is the

A) protopodite.
B) statocyst.
C) cheliped.
D) pedipalp.
E) exopodite.

14) What is the function of the green glands in the crayfish?

A) Secretion of fluids to aid digestion
B) Increasing oxygen absorption for respiration
C) Sensing vibrations in water
D) Reproduction
E) Excretion

15) The most accurate explanation of the management of nitrogenous wastes and ion balance in the crayfish is

A) the nitrogenous waste of crustaceans is excreted by the green glands and ion diffusion takes place by diffusion across thin areas of cuticle and the gills.
B) both ion balance and elimination of nitrogenous wastes is managed by the green glands.
C) hydrostatic pressure in the green glands forces fluid into the hemocoel and both ions, and nitrogenous wastes diffuse across thin areas of cuticle and the gills.
D) None of the choices is correct.
E) the nitrogenous waste of crustaceans is excreted by diffusion across thin areas of cuticle and the gills, while the so-called excretory organs regulate ion composition of the hemolymph.

16) The green glands form an effective "flood control" device in the freshwater crayfish by

A) forming a dilute, low-salt urine to unload the water that diffuses into the crayfish body.
B) forming a high-salt urine to unload the high salt built up in the crayfish body.
C) keeping the urine isosmotic to the blood.
D) keeping the interior hemocoel dry.
E) producing extra sodium and chloride ions to maintain the ionic balance.

17) The nerves of the eyes and the two pairs of antennae connect to the

A) statocyst.
B) supraesophageal ganglion.
C) subesophageal ganglion.
D) thoracic ganglion.
E) antennal glands.

18) If crayfish are raised in a very clean aquarium that only has iron filings in the floor, and they are allowed to go through several molts so that an iron filing is now serving as a statolith, what would be the effect of a large magnet suspended above the aquarium?

A) There would be no effect at all.
B) The crayfish would swim sideways.
C) The crayfish would swim upside down.
D) The crayfish would be unable to detect food.
E) The crayfish would be blind.

19) The photoreceptor cells in the crustacean compound eye are called

A) statocysts.
B) statoliths.
C) tactile hairs.
D) gastroliths.
E) ommatidia.

20) Which is a correct association of pigment and function in an arthropod compound eye?

A) Strong light—distal retinal pigment disappears
B) Strong light—each ommatidium is shielded from the others and sees only a limited area
C) Strong light—distal and proximal pigments separate
D) Dim light—each ommatidium is shielded from the others and sees only a limited area
E) Dim light—distal and proximal pigments fuse

21) The oldest ancestral and most widely-occurring crustacean larva is

A) a juvenile resembling the adult.
B) the trochophore.
C) the veliger.
D) the nauplius.
E) a planula.

22) Molting and subsequent ecdysis in crustaceans

A) involves production of a new cuticle and shedding of the old one.
B) is initiated by a stimulus perceived by the central nervous system.
C) involves a molt-inhibiting hormone produced by the X-organ of the eye stalk, and a molting hormone produced by the Y-organs near the mandibles.
D) cues on stimuli such as day length, temperature, or humidity.
E) All of the choices are correct.

23) Androgenic glands in the amphipod function to

A) regulate ion balance.
B) stimulate expression of male characteristics.
C) control pigmentation for camouflage.
D) secrete digestive fluids.
E) control ecdysis.

24) The crustacean group with the most ancestral features, including a long trunk with fairly uniform appendages, is

A) maxillopoda.
B) cirripedia.
C) isopoda.
D) decapoda.
E) remipedia.

25) A small group of hermaphroditic crustaceans that is unique in discharging both eggs and sperm through a common duct is

A) maxillopoda.
B) cirripedia.
C) cephalocarida.
D) decapoda.
E) remipedia.

26) Marine crustaceans that are sessile, secrete calcareous plates and filter-feed are

A) ostracods.
B) barnacles.
C) copepods.
D) decapods.
E) isopods.

27) The order that has been successful invading terrestrial environments is the

A) amphipoda.
B) euphausiacea.
C) cladocera.
D) decapoda.
E) isopoda.

FILL IN THE BLANK. Write the word or phrase that best completes each statement or answers the question.
28) The appendages of a crayfish are examples of serial __________.

29) The dorsal cuticle of the head of many crustaceans extends posteriorly to form a covering called the __________.

30) The two joints of the protopod are the lateral __________ and medial endopod.

31) The procuticle of crustaceans is often impregnated with __________.

32) A characteristic that is unique to crustaceans is the possession of two pairs of __________.

33) The process which culminates with arthropods regularly shedding their exoskeleton because it has become too small for the growing body is called __________.

34) Most appendages of crustaceans are two-branched, or __________.

35) Position sensors in the base of the first antennae of crayfish are called __________.

36) Crustaceans have better-developed sense organs than do the annelids because they have __________ hairs, which are delicate projections of cuticle distributed over the body.

37) When the juvenile that hatches from an egg resembles a miniature adult, the development is described as __________.

38) Water fleas, which belong to the branchiopodan order __________, often reproduce by parthenogenesis.

39) In crustaceans, the molt-inhibiting hormone is produced in the __________ -organ.

40) The individual units of compound eyes in crustaceans are called __________.

41) In the parasitic barnacle order Rhizocephala, the larvae metamorphose into a __________stage that injects cells into the hemocoel of the crab.

ESSAY. Write your answer in the space provided or on a separate sheet of paper.
42) Describe the sequence of events that occur during molting and ecdysis in a crayfish and explain why a "soft craw" is vulnerable until it has hardened its shell.

43) How does the statocyst work to communicate position to the crayfish?

44) Working with variable amounts of light, how do the various pigments in the ommatidium provide images of a variable field of vision or a continuous image?

45) Even though they are anchored in one place as adults, barnacles considered crustaceans. Explain why this is accepted.

46) Explain why pentastomids were placed in Ecdysozoa.

47) Crustaceans are often referred to as the "insects of the sea." This is partially because crustaceans are so abundant in the sea, as insects are on land, and because insects never successfully invaded the marine environment. Discuss why crustaceans 1) are so abundant in the ocean, and 2) why they did not radiate extensively into terrestrial environments.

48) Based on a count of individual organisms, a species in the copepod genus Calanus is likely the most abundant animal in the world. What features do copepods possess and what environmental factors contribute to this record status?

49) Both clams and crabs are referred to in common terminology as "shellfish." However, zoologists do not consider them to be closely related. Provide a contrasting list of the differences between the crustacean decapods and the molluscan bivalves.

50) Crustaceans and molluscs of course do have a common ancestor at some point. Draw a reasonable phylogeny that includes the molluscs, annelids and arthropods including the crustacea, and describe the distinguishing features on each branch. There are several legitimate phylogenies.

51) Discuss how modulation in expression of the Distal -less gene determines the location of distal ends of arthropod limbs. Why is this significant?

52) Why is the adaptive diversification of the crustaceans so great, while that of other groups, such as the annelids, so much less?

53) Discuss the evolutionary significance of the serial homology of crustacean appendages.

54) What is the evidence that the major tagmata in crustaceans are not homologous?