Class Bivalvia
(clams, mussels and oysters)
Major attibutes:
- Two shells made of calcium carbonate.
- Shell secreted by mantle.
- Ctenidia for respiration.
- Marine, estuarine or freshwater habitats.
- Microphagous, ciliary or filter feeders.
- Visceral mass with internal organs.
Description:
The bivalves consists of five subclasses: the Protobranchia, Pteriomorpha,
Paleoheterodonta, Heterodonta and Anamalodesmata. There are over 8000 species.
They have adductor muscles that work against the opposing, opening stress.
The mantle is attached to the shell. They have no differentiated head,
cephalic region or radula. A muscular foot is used for locomotion and burrowing.
Some interesting facts:
- They have a pair of ciliated labial palps on both
sides of the mouth which assist in selecting food.
- Some members are
gonochoristic, though most are hermaphroditic.
- Fertilization is mainly external and larva are either
free-swimming or parasitic.
Some pertinent books found in Lamson library:
- Buchsbaum, Ralph. 1976. Animals Without Backbones, Chicago:
University of Chicago.
- Parker, Sybil P. Synopsis and Classification of Living Organisms. vol.1,
NY: McGraw-Hill Book company.
(Gina M. Fratantuono, Fall 1994; edited by B. Miller, Spring 1995)
