1. Mollusca

2. General Characteristics
Coelomates
Protostomes
Body cavity called coelom is completely enclosed within the mesoderm
Specialized organs Ex. Stomach
Soft bodies
Toothed tongue called radula composed of chitin
Three distinct body zones
Head-foot
Visceral mass
Mantle

3. Classes Within Mollusca
Bivalvia
Monoplacophora
Ex. Clam
Ex. Neopilina

4. Gastropoda Cephalopoda Ex. Octopus Ex. Snail

5. Scaphopoda Polyplacophora Ex. Chiton Ex. Tusk Shell

6. Aplacophora Ex. Epimenia australis

7. Body Plan
Visceral mass contains digestive, excretory, and reproductive organs
Locomotion primarily done with muscular foot
Some have a differentiated head
The mantle is comprised of folds that arise from the dorsal body wall that enclose the cavity between the folds themselves and the visceral mass
Bivalve mollusks have two shells

8. Feeding
Radula used for feeding consists of thousands of microscopic chitinous teeth
Gastropods(Snails/relatives) use the radula to scrape food and then convey the food to the digestive tract.
Other gastropods use a modified radula as a drill to drill through shells of oysters and other creatures.
Has a closed digestive tract that goes from the mouth to the stomach to the intestine to the anus

9. Respiration
The mantle is a heavy fold of tissue wrapped around the body of the mollusk
the space between the mantle and the actual body is called the mantle cavity
This cavity in some mollusks acts as a lung
In other mollusks, it contains gills that capture the oxygen from the water when the water passes through the cavity

10. Circulation
All mollusks except cephalopods have an open circulatory system which blood flows freely throughout the body
The mollusk heart has there chambers: Two atria and one ventricle
Cephalopods have a closed circulatory system with blood vessels that carry the blood to all parts of the body and then diffuse it

11. Excretion
Nitrogenous wastes expelled by two tubular structures called nephridia
Each has an open funnel, nephrostome, lined with cilia
Coiled tubule runs from nephrostome to bladder, which connects to excretory pore
Wastes are gathered by nephridia from coelom and discharged into mantle cavity
Then are expelled by cavity by continuous gill pumping

12. Response
If carnivore, it can used chemosensory structures to locate prey.
Gastropods have tentacles with eyes on the end.
Cephalopods have highly developed nervous systems.
Brains unique among mollusks
Many exhibit complex patters of behavior/high level of intelligence
Very elaborate eyes, similar to vertebrate eyes

13. Movement Their foot is their primary mechanism of locomotion
Some mollusks secrete mucus, forming a path that they glide along on their foot
Cephalopods have foot which is divided into arms, also called tentacles.
In some pelagic forms, mollusks that are perpetually free swimming, the foot is modified into wing-like projections or thin fins

14. Reproduction Has distinct male/female individuals
Few bivalves/many gastropods are hermaphroditic
Cross fertilization is most common
Most aquatic mollusks engage in external fertilization
Gastropods often have internal fertilization

15. Works Cited
Bunje, Paul . "The Mollusca." University of California Museum of Paleontology. UCMP, Web. 19 Apr < berkeley.edu/taxa/inverts/mollusca/mollusca. php>.
"Gravysnail." Youtube. Web. 19 Apr 2010.
Raven, Peter and George Johnson. Biology. 6th ed. NY: McGraw-Hill, Print.
"Phylum Mollusca: Mollusks ." The Diversity of Life. N.p., n.d. Web. 19 Apr < infusion.allconet.org/webquest/PhylumMollus ca. html>.

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