Archerd Shell Collection > Shell Classes > Polyplacophora


Polyplacophora (Chiton) Page


Description:
 
About 800 existing species of chiton are identified. All are rock-dwelling marine molluscs with oval shaped bodies that are flattened from back to front (dorsoventrally). Eight overlapping and separate plates form the shell, and the plates are articulated by a fairly complex set of muscles. The class is designated from its name, Polyplacophora, which means "bearer of many plates."
 
Chitons are mainly found in shallow water, often under rocks and other shells, but several genera can be found in water as deep as 5,000 ft.. They become active at twilight and move around very slowly in search of food. Most are grazers, and with a multi-toothed radula, they can feed on small algae and other tiny organisms. Some are actively carnivorous, feeding on small crustaceans by smothering them with the girdle; e.g., Lepidochitona.
 
The anatomy of chitons is comparatively simple, and with no evidence of torsion. Nevertheless, despite a primitive nervous system, chitons in the subfamily Toniciinae (Tonicia and Acanthopleura) possess rather remarkable eyes. They are found in shallow, tropical waters. Most other chitons, and those in the Ischnochitonidae family, do not have developed eyes, although they may respond to light. Most seem to depend on tactile or chemically sensitive nerve endings to locate food.
 
Interestingly, aboriginal Australians are known to have roasted and eaten Acanthopleura, while aboriginal Bermudan islanders also harvested chitons to make a soup (Beesley et al., 1998). Today, they have   no commercial usefulness.

 

 


Classification:

 

Class: Polyplacophora
Order: Neoloricata
Suborder: Ischnochitonina (shallow water)
Family: Ischnochitonidae
  • Genus: Ischnochiton
  • Genus: Lepidochitona
  • Genus: Tonicella
  • Genus: Stenoplax
Family: Chitonidae
  • Genus: Acanthopleura
  • Genus: Chiton
  • Genus: Liolophura
  • Genus: Tonicia
Family: Mopaliidae
  • Genus: Katharina
  • Genus: Mopalia
  • Genus: Placiphorella
Suborder: Acanthochitonina (deep-water)
Family: Acanthochitonidae
  • Genus: Acanthochitona
  • Genus: Cryptochiton
Suborder: Lepidopleurina (deep-water)
Family: Lepidopleuridae
  • Genus: Leptochiton
  • Genus: Lepidopleurus

Stenoplax heathiana.JPG (56402 bytes)<
Stenoplax heathiana
Family: Ischnochitonidae

Chiton_albolineatus.JPG (38956 bytes)
Chiton albolineatus
White-striped Chiton
Family: Chitonidae

Mopalia_muscosa.JPG (53738 bytes)
Mopalia muscosa
Mossy Mopalia
(dorsal view & ventral views)
Family: Mopaliidae

 

SEE a LIVING CHITON TAKEN at 50 FT DEPTH
Courtesy of Kirt L. Onthank:

Tonicella lineata

 

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Archerd Shell Collection > Shell Classes > Chitons