Taxonomy of Shellfish

Unit 10 - Taxonomy of Phylum Mollusca

10.4 Key to the family Chitonidae

Phylum : Mollusca

Class : Amphineura

Order : Polyplacophora

Family : Chitonidae

Family Chitonidae

• The shell valves generally clearly demarcated lateral areas, sculptured or more rarely smooth.
• The insertion plates are characteristically pectinately toothed.
• The girdle is covered with scales, elongated spines or small bristles.

Genus Chiton

• Body elongate, elliptical with a convex dorsal surface.
• Shell divided into eight overlapping transverse calcareous plates. The first one is cephalic plate and the last one is anal plate.
• Foot, head and visceral mass ventral in position.
• Head small, cylindrical inconspicuous structure not distinctly marked off from the rest of the body; provided with a labial palp on either side of the mouth.
• Eyes and tentacles absent.
• Peripheral area of mantle, called the girdle very heavy extending beyond the lateral margins of the plates.
• Foot broad, flat and muscular.
• Pallial groove lodges ctenidia or gills, mid-ventral anus, two real apertures and two genital apertures.