Class Polyplacophora
(chitons)
Major Attributes:
- Possess eight calcareous plates that overlap to form a linear
chain.
- Surrounding mantle developed into thick girdle, often
bearing spines, scales or bristles.
- Poorly developed head.
- Lack eyes and sensory tentacles.
- Large radula with many teeth.
- Open circulatory system.
- Protostomate.
Description:
There are three orders and 550 species of polyplacophorans. The
orders differ according to the location of the gills in the mantle cavity, the
presence of teeth on the shell plates and the area the girdle covers on the
shell plates. The polyplacophorans are grazing marine herbivores that
mainly live in shallow waters. They range in size from 3.0 mm. to
40.0 mm.
Some Interesting Facts:
- Chitons are able to roll up into a ball when threatened.
- They are primarily shallow water organisms, but they have been found
in depths greater than 7,000 meters.
Some Pertinent Books Found in Lamson Library:
Banister, Keith and Andrew Campbell. 1985. The Encyclopedia of
Animal Life. NY: Facts on File.
Glynn, P.W. 1970. On the ecology of the Caribbean chitons
Acanthopleura granulata Gmelin and chiton Linne: density, morality,
feeding, reproduction, and growth. Washington: Smithsonian Institution Press.
(Krista A. Kuch)
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