Deck 10: Molluscs

Question 1

The class Gastropoda is the most diverse and ecologically the most successful mollusc group.

Answer 1

True

Question 2

The cephalopods are the marine active predators.

Answer 2

True

Question 3

In coelomate animals,the coelom

A)develops as a secondary cavity within the mesoderm.
B)is filled with fluid.
C)can serve as a hydrostatic skeleton.
D)all of these

Answer 3

D

Question 4

The Polyplacophora

A)have a coiled shell.
B)live in the ocean.
C)lack gills.
D)all of these

Question 5

The molluscs are the second most diverse phylum known.

Question 6

The water current in the body of a cephalopod mollusc provides

A)oxygen for respiration.
B)jet power for rapid locomotion.
C)a means of carrying wastes and gametes out of the body.
D)all of these

Question 7

Members of the class Monoplacophora were believed extinct until some living specimens were found off the coast of Costa Rica in 1952.

Question 8

Concerning reproduction in Bivalvia,

A)they tend to be hermaphroditic.
B)fertilization is usually external.
C)development is direct (no larva).
D)the adult stage is called a glochidium.

Question 9

Most molluscs are found in fresh water,but a few live in the ocean or on land.

Question 10

The mantle cavity in a mollusc houses the gills,foot,and head.

Question 11

The cephalopod __________ has a mantle length of 5 to 6 m,eyes up to 25 cm in diameter,and feeds on fish and other squids.

A)Tegelus
B)Cyphoma
C)Haliotis
D)Architeuthis

Question 12

Molluscs are important to humans because of their important ecological niches,because a variety of them are eaten,and because some kinds produce pearls.

Question 13

Molluscs evolved in fresh water,and therefore the majority of species are found in fresh water.

Question 14

The Solenogasters

A)live on the sea bottom and feed on cnidarians.
B)have a shell of eight articulating plates.
C)resemble the squids.
D)are called chitons.

Question 15

The characteristics that generally typify molluscs are

A)foot,mantle,protonephridia,shell.
B)radula,open circulation,mantle,shell.
C)coelom,mantle,closed circulation,radula.
D)no anus,pseudocoel,mantle,shell.

Question 16

The Monoplacophora

A)lack a shell.
B)live in fresh water.
C)have several internal organs that are serially repeated.
D)lack a foot.

Question 17

Some bivalves have an operculum which prevents drying when the tide goes out.
Multiple Choice Questions

Question 18

Locomotion in most of the Bivalvia is accomplished by

A)a muscular foot.
B)ciliary action.
C)jet propulsion.
D)all of these

Question 19

Chitons have eight plates embedded in their dorsal surface.

Question 20

The nudibranchs belong to the

A)ProsobranchiA.
B)Opisthobranchia.
C)Pulmonata.
D)Scaphopoda.

Question 21

Though they evolved from a torted ancestor,opisthobranchs have undergone various degrees of _________________.

Question 22

The empty chambers of Nautilus are connected by a cord of living tissue called the __________.

Question 23

The circulatory system of cephalopods is more efficient than other molluscs because it is ____________ and has accessory ___________ at the base of each gill.

Question 24

Most cephalopods can move by a kind of jet propulsion by expelling water through their _____________.

Question 25

The pulmonate snails lack gills,and their mantle cavity functions in an analogous fashion to a __________.

Question 26

Torsion in gastropods caused the mantle cavity and the organs it contained to lie above the _________.

Question 27

The shell of Polyplacophora is divided into (#)_________ valves.

Question 28

The circulatory system of cephalopods is more efficient than that of other molluscs because

A)it has blood.
B)it is closed.
C)cephalopods breathe air.
D)all of these

Question 29

The muscles which hold the valves of a bivalve together are the

A)umbo muscles.
B)adductor muscles.
C)synergist muscles.
D)fixator muscles.

Question 30

The group of molluscs which are most endangered are the

A)freshwater bivalves.
B)marine bivalves.
C)terrestrial gastropods.
D)marine gastropods.
Fill in the Blank Questions

Question 31

One group of molluscs in particular,the _____________,serve as intermediate hosts for many harmful parasites.

A)bivalves
B)chitons
C)gastropods
D)cephalopods

Question 32

Molluscs with a tubular shell,open at both ends are the class _____________.

Question 33

Opisthobranchs that have no shell or true gill are commonly known as ____________.

Question 34

Most cephalopod molluscs can change colors because of special pigment cells that are called _____________.

Question 35

With respect to obtaining food,most clams and related organisms can be described as ________.

Question 36

The edible clams,oysters,and scallops belong to the class _____________.

Question 37

The tongue-like,rasping organ in the head of most molluscs is the ______________.

Question 38

Many freshwater clams have specialized,parasitic ___________ larvae.

Question 39

The Polyplacophora are commonly called _______.

Question 40

The largest invertebrate known,the giant squid,belongs to the class _____________.

Question 41

Because of "coiling," most gastropods can be characterized as being bilaterally ___________.

Question 42

The most primitive conditions in today's molluscs are found in the ____________ with a mantle,calcareous spicules,a radula,and gills.

Question 43

The ______________ is a rod in the stomach of a bivalve which aids in digestion.

Question 44

Most cephalopods can secrete and expel an ink containing _____________ to confuse enemies.

Question 45

Classes _______________ and _______________ are small groups of wormlike molluscs with no shell.

Question 46

There are two hypotheses that explain molluscan evolution.In the _______ hypothesis,the wormlike body is the ancestral trait,but in the ______ hypothesis the multiple foot retractor muscles would be the ancestral trait.

Question 47

The ______________ is the outer layer of a typical mollusc shell.

Question 48

The shell of a mollusc is rich in the element _____________.