Chitons

Chitons are a primitive group of molluscs. They are distinctive and cannot be confused with any other marine animal, but are often overlooked because of their size and their habit of adhering to the undersides of rocks. They are oval with eight segmented plates the reason behind their common name the coat of mail shell.

The overlapping plates are surrounded by a mantle. This mantle provides a seal between the animal and the rocky surface, reducing waterloss when left uncovered by low tide. The mantle itself may bear spicules or bristles. The flexibility that the mantle and plates provide, allow chitons to adhere to uneven surfaces. If chitons are removed from the rock surface, the plates provide suficient flexibility for them to roll into a ball.

Chitons have one large foot which is surrounded by a groove, in which their gills lie. Chitons have a small head and possess no eyes or tentacles. They are grazers, rasping algae with their radula.

Chitons tightly cling to rock surfaces, to such a degree that they are almost impossible to remove without killing them.

In Cornwall there are two species found on rocky shores, the common grey chiton Lepidochitona cinerea and the bristly chiton Acanthochitona crinitus.