Summary

Hermit crabs are a superfamily of common, well known anomuran decapods and are not true crabs at all, walking in a regular forward motion rather than the typical sideways pattern of true crabs. Unlike other decapods, the abdomen of hermit crabs is soft and vulnerable as almost all hermit crabs rely on discarded gastropod mollusc shells for shelter, changing host as they grow. The ecology, morphology, physiology, behaviour and evolution of hermit crabs are all strongly tied to the reliance on these external shelters.

Dardanus megistos is amongst the largest of hermit crabs, growing to 30cm. It is often considered to be a deeper dwelling species, though at Heron Island at least, smaller individuals are not uncommon from the reef flat. Here it is most easily come across at low tide. Hermit crabs are shy, harmless and are easy to interact with. As well as D. megistos, there are several other species of hermit crab present at Heron Island, including the reasonably sized D. lagopodes and many smaller species.

Hermit crabs and decapods in general are well studied. However, hermit crabs in particular are under-represented in the Australian literature and little work has been done on the species commonly found at Heron Island. Specifically: population based studies, scientific description of larval development, detailed anatomical description, investigation of larval settlement and metamorphosis cues and behavioural studies concerning host shell preferences could all be considered novel topics of study for D. megistos and other hermit crabs of the Great Barrier Reef.

Photo: Storm Martin, Heron Island, 2012