Giant Gem Chiton, Acanthopleura gemmata


Explore some of the species of strange, armoured molluscs that can be found on the rocky shores of Queensland.


Chitons are an unusual type of marine mollusc belonging to the class Polyplacophora. They differ from other molluscs by having an 8-plated shell, which is held together by a tough, skirt-like band of tissues known as the ‘girdle’ (this may obscure the plates in some species). These protective, shield-like plates held securely in place by the girdle led to their other common name – coat of mail shells.

All chitons have a reduced head and a large foot and are associated with rock and reef habitats where they graze algae and small invertebrates from the surface. Chitons seek shelter under rocks or in crevices, especially during low tide to minimise exposure to predators and desiccation. The various types of chitons are distinguished by colour and structural differences in the plates and girdle. Globally there are more than 900 living species.

Common questions

Unlike the one or two-part calcified exterior of other shelled molluscs (e.g., marine snails and bivalves), this arrangement gives chitons the ability to roll-up into a protective ball if dislodged, and also to grip firmly to uneven, rocky surfaces.

Chitons feed on algae, micro-crustaceans, worms and other small invertebrates using their radula – a tooth-like tongue structure found in other types of molluscs.

Yes – although they are not a common restaurant option. However, they are consumed in many parts of the world including the Caribbean islands, the Philippines, South Korea, and by native peoples in parts of the Pacific coasts of North and South America and Australia.

Fact sheets


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