Download Mollusca Overview - Solon City Schools

Mollusc Characteristics
• Unsegmented soft body
– Visceral mass
• Molluscs have a Modified Foot
– Muscular foot and/or tentacles
• Have a mantle (fold in the body wall
that lines the shell)
• Most have shell (internal or external)
– Or remnants of a shell
• Pen in squid
Tentacles/
modified foot
head
Mantle
cavity
Mantle
foot
Shell
Classes of Molluscs
There are 8 classes of molluscs but this course will look at the 3 main classes
• Class Cephalopoda –
octopus and squid
• Class Gastropoda –
slugs and snails
• Class Bivalvia – clams,
mussels, scallops
.
Class Gastropoda
• free-living; marine, terrestrial, fresh water
• noticeable head
• single shell, often spiral
• muscular foot is attached near the stomach area
Class Bivalvia
• marine and freshwater
• gill used for gas exchange
• all are sessile, suspension feeders and
filter food from the water
• all have two part shells
(bivalves)
A giant clam can be 4 to 6 feet
in diameter!
Other Bivalves
The bivalves are the second largest class of molluscs.
They differ from snails in having two shells, usually mirror
images of each other. Some like oysters and mussels live
attached to rocks and other hard surfaces while others, like
pipis, burrow in sand. Leptonoidean bivalves (in picture)
are a group which usually live commensally with other
animals. Most have a large foot and are active crawlers
(1mm).
•
Limatula strangei. Some bivalves, such as the
scallops are able to actively move when endangered
by vigorously flapping their shells and squirting out
jets of water. Limatula also moves very vigorously
when disturbed. The tentacles around the mantle
edge are sticky, very mobile and parts can break off
them when the animal is disturbed, leaving a
potential predator with a sticky writhing worm-like
object to deal with as the Limatula escapes
(25mm).
Scallop with a “buddy” on top!
Bay Scallop
before cooking
Inside of
Bay Scallop
Cooked scallops!
YUMMY!
Class Cephalopoda
• Exclusively marine
• Shell- “pen”- internal
remnant of a shell
• Use fins and siphon to
move
• Modified foot= tentacles
• Fast swimming
predators
-use tentacles to catch
prey
• Have a special camera
like eye
Ex- Giant Squid
Squid External Anatomy
Fins
Mantle
Siphon
Squid Internal Anatomy
Squid swimming with Mrs. Ross
while scuba diving off the coast
of Jamaica
Can you see the
squid?
Do you think
these squid are
related?
BEFORE….
AFTER!
So, when do I get to see you
and your relatives photos?