molluscs

Question 1

molluscs are protostomes. describe protostomes

Answer 1

first embryotic opening is the mouth

Question 2

what kind of coelomate (body cavity lined by mesoderm cells) are molluscs?

Answer 2

shizocoelomate / coelomate: coelom formed by splitting of mesoderm

Question 3

what kind of digestive system do molluscs have?

Answer 3

complete digestive system (one way)

Question 4

what kind of symmetry

Answer 4

bilateral

Question 5

what level of organization?

Answer 5

Organ level

Question 6

what layers do molluscs have?

Answer 6

endo, meso, ecto derm

Question 7

what three main parts are a molluscs body composed of and describe them

Answer 7

1. visceral mass: soft bodied portion with internal organs
2. foot: muscular portion for locomotion
3. mantle: membranous/muscular covering envelops visceral mass. may secrete a shell

Question 8

molluscs may have a head region with…

Answer 8

• eyes
• other sense organs

Question 9

what contributes to the molluscs diversity and how can they be distinguished?

Answer 9

• division of body parts
• modification of the foot

Question 10

what is the radula?

Answer 10

toothy, raspy tongue-like structure

Question 11

gastropods are _____ footed. describe their feet and how they move

Answer 11

• stomach-footed
• foot is ventrally flattened
• moves by muscle contractions that pass along the foot

Question 12

cephalopods are ________ footed. describe their physical characteristics

Answer 12

head footed

• tentacles
• beak and radula to tear prey
• cephalization
• eyes similar to vertebraes: lens, retina with photoreceptors

Question 13

cephalopods brain was formed from a fusion of _____

Answer 13

ganglia (groups of nerves/brain cells)

Question 14

what do large pairs of nerves in cephalopods contol?

Answer 14

rapid contraction of the mantle

Question 15

rapid contraction of the mantle in cephalopods allows for what kind of movement?

Answer 15

quick movement by a jet propulsion of water

Question 16

what kind of circulatory system do cephalopods have? describe

Answer 16

closed: blood remains in organs and blood vessels. increase in blood pressure