adaptation and variation in 4 classes of molluscs Flashcards
what are the key characteristics of molluscs
fott
radula
shell
mantle
foot
muscular; usually ventrally located and generally used for locomotion
radula
a scraping oral structure which is unique to mollusks
shelll
either an external calcium carbonate shell or an internal chiton shell
mantle
an organ that secretes the shell
Chiton (polyplacophora)
-have a reduced head and flat body protected by segmented plates
-large ventral foot is adapted for clinging tightly to rocks that are expose to waves
-the radula in chiton is used like teeth for scraping algae of rocks
-the muscular foot is very strong and undulates during movement
-there are 8 plates that make up the shell; light-sensitive organs on the shell allow the chiton to move away from sunlight and find a darker, cooler place to feed
-live in rocky intertidal zones
Clam
-class: bivalvia
-they have 2 halves
-move by digging their foot. They burrow into the sand or mud to feed at the bottom of the ocean or freshwater area
- they are filter feeders and have
-no radula
-live in the open ocean during larval stage and then as adults move to the floor of oceans or bays
-mantle secretes the shell allowing the shell to grow as the internal organs grow
-muscles keep the shell closed and when the muscles relax the shell can open, allowing the foot to dig up into the sand and siphon to reach up into the water.
the siphon filters food and water through the gills an into the mouth
what are clam gills used for
respiration and feeding
snail
-class gastropods
-largest class of molluscs
-live in the ocean, in freshwater, and on land
- have a broad foot used to creep; they have a mucus secretion that helps aid locomotion by preventing injury to the foot
-have radulas that allow them to scrape algae from the surface of rocks, aquarium, and other shell in order to feed
what does the visceral mass in the shells of snail do
it holds the bulk of the digestive, reproductive , excretory, and respiratory systems
benefit of torsion
gives it the ability to retract into the shell if in any danger. Allows for elongation in growth without toppling sideways
squid
-class cephaalopoda
-most active group of molluscs
- open-ocean swimmers
-their shell is reduced and internalized
-they do not have radula to aid in feeding
-they have a siphon used for locomotion
-muscular contractions force water through the siphon, propelling the squid through the water,
-the siphon is a modification of the foot
which mollusc lives in rockey intertidal zones
chiton; class polyplacophora
in this mollusc the ventral foot clings to rocks in area where waves constantly hit the rock surface
chiton; class polyplacophora
this mollusc is known to have a radula stronger than a kitchen knife to scrape algae off rock
chiton; class polyplacophora
this mollusc is armor plated; 8plates that make up their shell
chiton; class polyplacophora
this mollusc has light-sensitive organs on their shell that allow it to move away from the sunlight
chiton; class polyplacophora
which mollusc moves by burrowing its foot into the sand mud
clam; class bivalvia
this mollusc lives in the open ocean when younger, but as an adult moves toward the floor of the oceans
clam; class bivalvia
the mantle of this mollusc secretes the shell allowing the shell to grow as the internal organs grow
clam; class bivalvia
in this mollusc when the muscles relaxes the shell opens, which allows the foot to dig into the sand and the siphon to reach up into the water
clam; bivalvia
this mollusc has no radula
clam; bivalvia
what is the siphon a modification of in clams?
mantles
this type of mollusc lives in ocean, freshwater, and land
snail; class gastropoda
