Phylum Mollusca:Chitons

Question 1

Characteristics

Answer 1

Dorso-ventral differentiation (visceropallium and cephalopodium)
Calcium Carbonate shell
Mantle cavity, gills, osphradia (sensory), shell-attached muscles

Question 2

Reduced Coelom (pericardium)

Answer 2

The coelom is the dorsal blood vessel, that forms a heart
Outpocketing of the coelom forms a true compartment for gonads
Metanephridia is also a coelomic compartment

Question 3

Digestive Tract

Answer 3

Buccal activity, with stomach, attached digestive glands, intestine, anus and radula sac (radular teeth) with associated radular cartilage

Question 4

Nervous System

Answer 4

Circumpharyngeal nerve ring with 2 pairs of nerve cords.
A pair of visceropallial nerve cords dorsally
A pair of pedal nerve cords ventrally

Question 5

Distinctive characteristics of chitons (5)

Answer 5

Minimal cephalization
Dorso-ventral flattening
Dorsal shell as 8 articulating pieces 
Mantle assists with substrate adhesion
Radula with caps of magnetite

Question 6

Reproduction (4)

Answer 6

Dioecious
Broadcast spawn gametes
External fertilization
Ciliated, non-feeding larva