Section 21.1- Mollusks

Question 1

the largest group of water animals on Earth

Answer 1

mollusks

Question 2

mollusks are distinguishable by

Answer 2

muscular FOOT
VISCERAL HUMP
MANTLE

Question 3

contains internal organs

Answer 3

visceral hump

Question 4

used for locomotion

Answer 4

foot

Question 5

skinlike organ that covers the visceral hump and produces carbonate calcium shell for protection

Answer 5

mantle

Question 6

the most familiar classes of mollusks

Answer 6

bivalves
gastropods (univalves)
cephalopods

Question 7

two-shelled mollusks

clams, scallops, oysters, mussels

Answer 7

bivalves

Question 8

edible clams, scallops, oysters, mussels are called

Answer 8

shellfish

Question 9

each shell of a bivalve consists of________ distinct layers

Answer 9

three

Question 10

the inner shell layer of some inedible oysters and clams is called

Answer 10

mother-of-pearl

Question 11

the substance from which the pearly layer is formed in a clam or oyster is formed

Answer 11

nacre

Question 12

the sheets of nacre build up around the irritant and eventually form a

Answer 12

pearl

Question 13

hold together the two shells of a bivalve

the main parts of the scallops and muscles that are eaten

Answer 13

adductor muscles

Question 14

a clam uses its foot for …

Answer 14

burrowing very quickly into the sand

Question 15

scallops swim rapidly by

Answer 15

opening and closing shells

Question 16

oysters are

Answer 16

sessile

Question 17

one of the most critical activities for a bivalve is the movement of water into and out of its ____________

the open chamber in which gills are located

Answer 17

mantle cavity

Question 18

the siphon in the mantle cavity that takes water into the mantle cavity to the gills

Answer 18

incurrent siphon

Question 19

where oxygen and carbon dioxide are echanged in bivalves

Answer 19

gills

Question 20

most of the water passes out of the mantle cavity and gills through the

Answer 20

excurrent siphon

Question 21

a bivalve has an ____________ circulatory system

Answer 21

open

Question 22

bivalves have a well-developed _______ system

Answer 22

nervous

Question 23

reproduction in most bivalves is sexual, with ________________ fertilization

Answer 23

external

Question 24

stomach-footed mollusks that are often called univalves because most of them have one shell

Answer 24

gastropods

Question 25

when a gastropod’s shell spirals clockwise to open on the right

Answer 25

right-handed or dextral

Question 26

a few univalve shells spiral counterclockwise and are said to be

Answer 26

left-handed or sinistral

Question 27

T/F: All gastropods have shells

Answer 27

FALSE

Question 28

gastropods that look like snails without shells

Answer 28

slugs

Question 29

marine slugs that include some of the most beautiful and graceful sea creatures

Answer 29

nudibranchs

Question 30

T/F: Univalves have a visceral hump, foot, and (usually) shell

Answer 30

TRUE

Question 31

the gastropod’s belly rests on its

Answer 31

foot

Question 32

a rough, filelike organ found in univalves that scrapes food and carries it like a conveyer belt into the digestice tract

Answer 32

radula

Question 33

consists of octopus, squid, cuttlefish, and chambered nautilus

head-foot mollusks

Answer 33

cephalopods

Question 34

a torpedo shaped cephalopod noted for its ability to move by “jet propulsion” by forcing water out of a siphon

Answer 34

squid

Question 35

three categories of squids

Answer 35

common squid (large numbers in marine waters)
giant squid (found in temperate regions of ocean)
colossal squid (lives in the oceans around Antarctica)

Question 36

the largest invertebrates

Answer 36

colossal squids

Question 37

cephalopods have a ______________ circulatory system

Answer 37

CLOSED

Question 38

cephalopod that has 8 arms which are studded with suction cups for catching prey

Answer 38

octopus

Question 39

the most conspicuous part of the octopus is the

Answer 39

head

Question 40

the only cephalopod with an external shell

Answer 40

nautilus

Question 41

the angles of the chambers of a nautilus are mathematically precise and form what mathematicians call a

Answer 41

logarithmic spiral

Question 42

cephalopod with poorest vision

Answer 42

nautilus