Zoology Phylum Mollusk. I. Intro to Mollusks A. Mollusk soft bodied B. 2 nd largest phyla 1. small large 2. fast movers slow movers 3. intelligent.

Zoology

Phylum Mollusk

I. Intro to MollusksA. Mollusk soft bodied

B. 2nd largest phyla

1. small large

2. fast movers slow movers

3. intelligent non-intelligent

4. Deep seas mountain tops

C. Ex: squid, clam, oyster, octopus, snail, slugs, etc.

D. Used as a food source

1. clams, oysters, etc.

E. Used for jewelry (pearls)

F. All have a “foot” specialized muscular organ

II. Cephalopods

A. Facts

1. Cephalo = head / poda = foot

2. Includes…squid, octopus, nautilus

3. Active predators

4. shell nautilus

5. no shell octopus + squid

B. The Nautilus

1. Locomotion-”foot” acts as a siphon pushes water out-gas filled chambers

2. Nervous System-intelligent-chemoreceptor cell used to camouflage

3. Others-60 to 90 tentacles (no suckers)-sexual reproduction-radula tongue like structure

i. 250,000 teeth ii. Conveyor belt

C. The Squid

1. Locomotion-same as nautilus

2. Nervous System-exceptional eyes-chemoreceptor cell

3. Others-sepia ink sac; helps hide

from enemies-8 arms / 2 tentacles-pen acts as backbone of

squid-beak – used to break up food

D. The Octopus

1. Locomotion – same as squid2. Nervous System

-great eye sight-extremely intelligent (can be conditioned)-chemoreceptor cells

3. Others-sepia -pen-8 arms – all with suction cups-beak – used to break up food

III. GastropodsA. Facts

1. gaster = stomach / poda = foot2. Largest group of mollusks (50,000)3. Ex: snails and slugs4. Dioecious (individual sexes) or

monoecious (both sexes)5. can be terrestrial (gills or lungs)6. Sluggish or slow moving7. Usually feed on algae or plankton8. Occupy a shell for protection

B. Conus

1. active predator

2. uses worm-like tongue to lure in prey

-fish bites…proboscis fires…injects venom…paralyzes fish

3. lethal sting to humans

IV. Class Pelecypoda (Bivalves)

A. Facts

1. pelecy = hatchet / poda = foot

2. Ex: mussels, clams, scallops, oysters

3. Filter Feeders

4. no radula

5. Dioecious

B. The Clam

1. External Anatomy

a. Umbo – oldest part of the shell

b. Hinge Ligament – keeps the 2 shells connected

c. Growth Rings

Growth Rings1.

2. Umbo

Anterior Side

Ventral Side

3. Hinge Ligament

2. Internal Anatomy

a. Siphons

-incurrent takes water + food into clam

-excurrent removes waste

b. Mantle – tissue that covers the organs of the clam

-similar to skin

c. Palp – guide food into the mouth

d. Heart

-3 chambered

-beats slow (0.2 – 30 times/min.)

e. Kidneys

-filter blood

-U shaped

-Nephridial Tubules – connect to the kidney

f. Ganglia

-3 pairs

-poorly developed

g. Muscles

-anterior adductor

-posterior adductor

-both close the shell

-Extremely strong