mollusca

Question 1

animals in the phylum mollusca are calcareous, what does this mean?

Answer 1

they have a shell enclosing a soft body, but the shell may be lost or reduced in many taxa

Question 2

what are some characteristics of mollusca?

Answer 2

1. they have a complete digestive system with a mouth
2. they have a true coelom
3. open circulatory system (no blood vessels and the coelom is small)
4. not clearly segmented

Question 3

mollusca have a mantle, what is it?

Answer 3

a thin layer of tissue that secretes the shell

Question 4

how do molluscs move?

Answer 4

muscular ventral foot

Question 5

where are a molluscs organs?

Answer 5

inside the visceral mass above the foot

Question 6

molluscs have a radula, what is it?

Answer 6

a mouthpart that has a strap-like rasping (conveyor belt with hooks/spikes)

Question 7

how do molluscs breathe?

Answer 7

gills for gas exchange and sometimes feeding

Question 8

what are the three classes of molluscs?

Answer 8

gastropoda, bivalvia, cephalopoda

Question 9

what is the most abundant class of molluscs?

Answer 9

gastropoda

Question 10

what animals does the class gastropoda encompass?

Answer 10

snails and slugs

Question 11

how do gastropods move?

Answer 11

through slime excretion, then use their muscular foot to move across the substrate

Question 12

during the larval stage, gastropods undergo _________. what is it?

Answer 12

torsion - visceral mass twists during development where their anal opening is over their head

Question 13

do gastropods have direct development?

Answer 13

only terrestrial and freshwater species, marine species have a larval stage

Question 14

how do land snails and slugs exchange gasses?

Answer 14

using a lung, which is the lining of their mantle cavity

Question 15

gastropods have a division called nudibranchs, what are they and their characteristics?

Answer 15

marine shell-less gastropods (sea slugs)
1. many are bright and vibrantly colored
2. protected by nematocysts of cnidarians (other animals)

Question 16

how are nudibranchs protected by the nematocysts of cnidarians?

Answer 16

eat cnidarians, but prevent their nematocysts from firing but instead storing it in their own tissues and firing the nematocysts when threatened

Question 17

where does the term ‘bivalvia’ come from?

Answer 17

having two hinged shells

Question 18

what animals does the class bivalvia encompass?

Answer 18

clams, oysters, muscles and scallops

Question 19

what are some characteristics of bivalves?

Answer 19

1. filter feed by drawing water through the gills
2. no radula (no definitive head)
3. most are sedentary (can move if needed)

Question 20

what animals does the class cephalopoda consist of?

Answer 20

squids, cuttlefish and octopus

Question 21

do cephalopods have a shell?

Answer 21

no external shell (except nautilus) and some have internal shell remnants (cuttlefish)

Question 22

how do cephalopods eat?

Answer 22

long tentacles that have suckers or hooks around their mouths

Question 23

do cephalopods have a radula?

Answer 23

no, it was modified into a biting beak

Question 24

how do cephalopods move?

Answer 24

they have a siphon (a fused tube of the mantle) in which they propel water though

Question 25

cephalopods are the only molluscs with a?

Answer 25

closed circulatory system which supports their active lifestyle

Question 26

do cephalopods have direct development?

Answer 26

yes

Question 27

cephalopods provide maternal care, what is that?

Answer 27

they protect their eggs until young hatch

Question 28

what are some characteristics of octopus?

Answer 28

excellent vision and have complex behavior