Chapter 10-Mollusks

Question 1

What does Phylum Mollusca consist of?

Answer 1

clams, mussels, scallops, oysters, snails, slugs, nudibranchs (sea slugs), cuttlefish, squids, and octopuses

Question 2

What is a mollusk?

Answer 2

soft-bodied creature with some sort of shell

Question 3

Where do most mollusks live?

Answer 3

marine environments; many freshwater and terrestrial environments

Question 4

What are the 3 parts of a basic mollusk body plan?

Answer 4

mantle, foot, visceral mass

Question 5

What is the mantle cavity?

Answer 5

space through which water, or in some cases air, circulates

Question 6

What is the reason for the circulation?

Answer 6

fresh oxygen for gas exchange

Question 7

What is Ctenidia?

Answer 7

vascularized filamentous projections derived for the mantle, housed within the mantle cavity and function as gills in aquatic species

Question 8

T/F Nitrogenous waste from excretory system and solid wastes from the digestive system empty into the mantle cavity and are swept away in a current flow.

Answer 8

True

Question 9

What does the mantle produce?

Answer 9

shell

Question 10

What is the foot and what does it do?

Answer 10

muscular structure used for locomotion by most mollusks, some specifically for prey capture

Question 11

What does the visceral mass contain?

Answer 11

most of the internal organs such as the digestive, excretory, and reproductive systems

Question 12

What is the coelom like in mollusks?

Answer 12

small spaces around excretory organs, heart, and intestines

Question 13

What does the shell contain?

Answer 13

2 layer sof calcium carbonate covered by an organic layer of the protein conchin

Question 14

What is the outer layer of shell?

Answer 14

periostracum which protects the inner calcium-rich layers from erosion

Question 15

What is the inner layer of shell?

Answer 15

nacreous layer which is secreted continuously by the mantle

Question 16

What is the layer between the periostracum and nacreous layer?

Answer 16

prismatic layer made form densely packed crystals of calcium carbonate

Question 17

What is the shell used as?

Answer 17

spacious retreat for the soft and vulnerable body; in some groups the shell has been reduced, internalized, or lost (slugs, cephalopods, cuttlefish, squid and octopus)

Question 18

What are member of the Class Polyplacophora called?

Answer 18

chitons

Question 19

What are characteristics of Class Polyplacophora?

Answer 19

grazing herbivores found in shallow marine environments, have dorsoventrally flattened ovoid bodies covered with 8 overlapping calcareous plates; head is poorly developed and hidden beneath a girdle formed by a thick mantle; most of ventral surface occupied by a large, muscular, elongate foot which animal uses to move slowly across a hard substrates

Question 20

What do chitons use the foot for?

Answer 20

suction, adhere tightly to surfaces

Question 21

What do chitons lack?

Answer 21

antennae and eyes

Question 22

What is a radula?

Answer 22

hard, grooved surface that animals use to scrape and grind algae off rock and other surfaces

Question 23

What is the mantle cavity’s purpose in chitons?

Answer 23

contains ctenidia (gills), surrounds foot on all sides

Question 24

What animals are in Class Bivalvia?

Answer 24

clams, mussels, scallops, and oysters

Question 25

Where do bivalves live?

Answer 25

most are marine and some live in freshwater

Question 26

How are bivalves usually recognized?

Answer 26

2 lateral shells hinged together and causes them to gape open

Question 27

What draws the 2 shells together?

Answer 27

one or two large adductor muscles

Question 28

What does the mantle secrete?

Answer 28

shells and ligament and envelops the internal organs within the shells

Question 29

How do pearls form?

Answer 29

irritant like a grain of sand, lodges between the mantle and the shell, the mantle responds by surrounding the irritant with layers of the same crystalline material used for the shell

Question 30

What is the foot used for in Class Bivalvia?

Answer 30

anchoring animal to substrate, creeping, or burrowing in soft sediments

Question 31

Do bivalves have a radula?

Answer 31

no

Question 32

Do bivalves have a distinct head region?

Answer 32

no

Question 33

How do members of Class Bivalvia capture food?

Answer 33

gills; water circulates through mantle cavity and small food particles trapped in mucus covering gill surface; near mouth, food particles are gathered by flaps of tissue called labial palps which roll to direct food in the mouth; movement of cilia on surface of gills also creates current flow through the mantle cavity; water enters and leaves the mantle cavity through openings called siphons

Question 34

What do siphons do in the bivalves that burrow?

Answer 34

extend to surface of the substrate to facilitate water circulation through the body

Question 35

What animals belong to Class Gastropoda?

Answer 35

limpets, snails, slugs, and nudibranchs (sea slugs)

Question 36

Do gastropods have shells?

Answer 36

most do which is often coiled, slugs and nudibranchs have lost their shell

Question 37

How do gastropods move?

Answer 37

crawl on muscular foot, but foot has been modified in some for swimming such as nudibranchs

Question 38

Do gastropods have a radula?

Answer 38

yes, used for scraping food off of hard surfaces

Question 39

T/F Gastropods are herbivores but some are scavengers or predators.

Answer 39

True

Question 40

Gastropods go though torsion. What is torsion?

Answer 40

asymmetric growth that repositions the mantle cavity and anus form the posterior part of the body a location nearer to the head

Question 41

What species belong to Class Cepahlopoda?

Answer 41

squid, octopus, cuttlefish, and nautilus

Question 42

T/F Cephalopods are herbivores.

Answer 42

False: carnivorous

Question 43

How are cephalopods specialized?

Answer 43

well developed sensory, nervous, locomotion systems; largest brains and well-developed eyes among invertebrates

Question 44

What are features of the cephalopod body?

Answer 44

consists of a foot, head, and visceral mass as we'll as a mantle, mantle cavity, radula, paired gills, and reduced shell

Question 45

Where are the fills housed in cephalopods?

Answer 45

mantle cavity

Question 46

What makes a foot in a cephalopod so unique?

Answer 46

developed into a ring of arms and tentacles which are usually covered in suction cups

Question 47

What are the arms used for?

Answer 47

appendages for capturing prey but in octopus arms they are also used for locomotion

Question 48

How does water flow in cephalopods?

Answer 48

muscular action of the mantle wall-drawn in mantle cavity by mantle expansion, when mantle contracts, it forms a tight seal around visceral mass and then forces the water out a narrow tubular funnel (siphon) exiting mantle cavity

Question 49

What is the pen or cuttlebone for?

Answer 49

counter the tendency of the body to lengthen during muscle contractions