2. 50,000 or more species of mollusks.
Characteristics:
Bilateral symmetry.
Body enclosed by the mantle that may secrete a
shell made of minerals.
A muscular foot that is highly modified among the various
groups of mollusks.
Head withy sensory organs and a mouth.
3. Characteristics:
Aquatic mollusks have gills. Terrestrial mollusks have
lungs.
Herbivorous or carnivorous. All of them with a complex
digestive system.
Most of them are hermaphrodites.
Most of them lay eggs from which a larvae emerges. It
will go under metamorphosis.
Have a true heart
Simple to complex nervous system
4.
5. There are seven mollusc classes. We will
study 3 of them:
Gastropoda (gastro=body cavity;
poda=foot)
Ex. Common garden snail, limpets and slugs
6. There are seven mollusc classes. We will
study 3 of them:
Gastropoda (gastro=body cavity;
poda=foot)
Ex. Common garden snail, abalone, turban
snail
Bivalvia (bi=two; valvia=valves)
Ex. Clam
7. There are seven mollusc classes. We will
study 3 of them:
Gastropoda (gastro=body cavity;
poda=foot)
Ex. Common garden snail, abalone, turban
snail
Bivalvia (bi=two; valvia=valves)
Ex. Clam
Cephalopoda (cephalo=dealing with
head; poda=foot)
Ex. Squid, octopus, sepia, nautilus, etc.
9. They have a dorsally located shell
(often coiled).
They have a well-developed radula.
Head with mouth and 4 tentacles (2
optic and 2 sensory)
Muscular foot to crawl.
11. They have no head.
They have two shells held
together by powerful
muscles.
They tend to burrow using
the foot.
Large gills are used for
respiration and filter feeding.
Water enters and exits
through siphons.
14. Internal shell or no shell (like an octopus)
The foot is highly modified to form a group of
tentacles around the mouth.
Squids & Nautilus are free-swimming and
move very quickly. Octopuses are found
among rocks or crawling on the bottom of
the ocean.
Complex brain, two lateral eyes, excellent
eyesight.
Strong jaw and radula
Closed circulatory system