Phylum Mollusca Flashcards
1
Q
What are the general characteristics of phylum Mollusca?
A
- eucoelom
- bilateral symmetry
- has well developed organ system
- open circulatory system
- uses radula for feeding
- muscular foot for locomotion
- uses gills, lungs, mantle cavity or body surface for gas exchange
- metanephridia for osmoregulation
- cephalization
- has trocophore larva
2
Q
How does a mollusc reproduce?
A
- most are dioecious
- can be hermaphrodites
- most have TWO larval stages eg. veliger and trocophore
3
Q
What are characteristics of class Polyplacophora?
A
- these are the chitons
- have eight articulating plates or valves
- mantle cavity houses gills on two sides
- separate sexes where eggs are fertilized in the mantle cavity
- ONLY has trocophore larva
4
Q
What are the characteristics of class Scaphopoda?
A
- these are the tusk shells
- sedentary marine molluscs
- foot used for burrowing
- feed on protozoa and detritus with tentacles
- no gills so gas exchange is across mantle surface
5
Q
What are the characteristics of class Gastropoda?
A
- limpets, snails are in this class
- they are secondarily asymmetrical due to torsion
- some have extensible proboscis with radula
- are dioecious or hermaphroditic although copulation is common
- VELIGER larva present in marine species
6
Q
What is torsion?
A
- rotation of the visceral mass, mantle and shell 180 degrees
- occurs during larval development
- brings mantle cavity and anus to anterior position above head
7
Q
What are the characteristics of class Bivalvia?
A
- these are the clams etc.
- shell with two valves
- are sedentary suspension feeders
- NO head or radula
- limited cephalization
- has separate sexes
- has both trocophore and veliger larva
8
Q
What are the characteristics of class Cephalopoda?
A
- these are the octopus, squid etc.
- locomotion is by jet propulsion
- can use chromatophores for colour change
- has ink sac for defense
- has separate sexes and copulation occurs with tentacle transfer of sperm sac
