Mollusca 2

Question 1

8 Classes

Remember Podas and Phoras

Answer 1

1. Chaetodermomorpha
2. Neomeniomorpha
3. Monoplacophora
4. Polyplacophora
5. Gastropoda
6. Bivalvia
7. Scaphopoda
8. Cephalopoda

Question 2

Radulae

4 points

Answer 2

1. raking/combing
2. rasping
3. drilling
4. poisoning

Question 3

Class Chaetodermomorpha

Answer 3

1. Shell-less and vermiform [form of worm]
2. Chitinous cuticle
3. Lacking a foot; poorly developed head without eyes and cephalic tentacles
4. One pair of bipectinate ctenidia [comb like either side]
5. Burrow-dwelling deposit feeders [organic matter settled on bottom]

Question 4

Class Neomeniomorpha

7 points

Answer 4

1. Shell-less, vermiform, reduced head.
2. laterally compressed
3. Longitudinal ventral groove; mantle covering body; ~80% have a radula (1 tooth)
4. Feed on cnidaria
5. Without ctenidia or one pair of ctenidia
6. Hermaphrodites,
7. internal fertilisation

Question 5

Class Monoplacophora

5 points

Answer 5

1. Single conical shell
2. Weak, muscular foot; distinct but poorly developed head without eyes and cephalic tentacles; well developed radula
3. Extensive mantle cavity
4. Three to six pairs of unipectinate ctenidia
5. Paired kidneys and heart atria

Question 6

Class Polyplacophora

5 points

Answer 6

1. Dorsally-compressed body.
2. Eight overlapping dorsal shell plates and girdle
3. Large muscular foot; poorly developed head without eyes and cephalic tentacles
4. Six to 88 bipectinate ctenidia
5. Large radula - feed on micro- and macroalgae

Question 7

Class Gastropoda

7 points

Answer 7

1. Very large diverse group
2. Characteristic torsion of body
3. Well-developed crawling foot; well-defined head; single, thick spirally coiled shell
4. Uni or bipectinate ctenidia
5. Calcareous operculum (often)
6. Dioecious and hermaphroditic
7. Trochophore and veliger larva

Question 8

Class Gastropoda

Answer 8

Subclass Prosobranchia
Spirally coiled or cap-shaped shell

Head with tentacles bearing basal eyes

Large muscular foot and operculum

Subclass Opisthobranchia
Thin, reduced shell

Reduced mantle cavity and ctenidia; no operculum

Head with 1-2 pairs of tentacles

Hermaphroditic 
Subclass Pulmonata
Terrestrial

Question 9

Class Bivalvia

Answer 9

1. Laterally compressed encased within a pair of valves
2. Foot laterally compressed; head reduced without eyes and cephalic tentacles
3. No radula - suspension feeders
4. One pair of bipectinate ctenidia
5. Water current drawn into mantle cavity
6. Inhalent and exhalent siphons [tubes]

Question 10

Class Scaphopoda

5 points

Answer 10

1. Single tubular shell. (2-150mm)
2. Burrowing foot; small head without eyes and cephalic tentacles; radula
3. Deposit feeders - Captacula and radula
4. Lack ctenidia
5. Dioecious, external fertilisation

Question 11

Class Cephalopoda

5 points

Answer 11

1. Anatomically and behaviourally the most sophisticated of all invertebrates
2. No foot - prehensile arms and muscular funnel
3. Head with complex eyes; radula and beak
4. Predatory
5. Pelagic
   Move using arms and siphon