chapter 37 section 1

Question 1

One advantage of a coelom over a pseudocoelom is that a coelom

Answer 1

allows body wall muscles to contract without hindering digestion

Question 2

One feature that is shared by many mollusks and annelids is the

Answer 2

trochophore

Question 3

. Mollusks in the class Gastropoda

Answer 3

have an open circulatory system

Question 4

Bivalves have the following structures

Answer 4

adductor muscles
siphons
gills

Question 5

An octopus generally moves by

Answer 5

crawling along the bottom with its tentacles

Question 6

Identify the two main regions of a typical mollusk’s body

Answer 6

. The two main regions are the head-foot and the

visceral mass.

Question 7

Which region contains most of the internal organs?

Answer 7

The visceral mass contains most of

the internal organs.

Question 8

Which region is directly involved with locomotion?

Answer 8

The head-foot is directly

involved with locomotion

Question 9

. What is the usual function of the mantle in a snail or clam?

Answer 9

The mantle secretes the protective shell.

Question 10

Contrast the feeding methods of gastropods and bivalves.

Answer 10

Gastropods use their radula to cut through leaves,
scrape up algae, drill holes through the shells of
other mollusks, and harpoon prey; bivalves filter
small organisms from the water that passes
through their gills.

Question 11

Contrast sexual reproduction of marine clams and most freshwater clams.

Answer 11

Marine clams shed sperm and eggs into the water,
and fertilization occurs externally. In most freshwater
clams, eggs are fertilized internally by
sperm that enter through the incurrent siphon

Question 12

A cephalopod called the paper nautilus makes a type of shell with its foot.
This shell, which consists largely of protein, is formed only by the female and is used to protect
the eggs. List four reasons why this shell is not a typical molluskan shell

Answer 12

A typical molluskan shell is secreted by the mantle,
consists of calcium carbonate, is formed by both
males and females, and protects the entire animal.

Question 13

torsion

Answer 13

in gastropods, the visceral mass twists 180 degrees in relation to the gastropods head

Question 14

hemolymph

Answer 14

the fluid in a open circulatory system.

Question 15

hemocoel

Answer 15

a set of hemolymph filled spaces in the tissues of an animal with an open circulatory system

Question 16

bivalve

Answer 16

have their shells divided into two halves and connected by a hinge

Question 17

adductor muscles

Answer 17

bivalves close its shell by contracting its adductor muscles