It’s hard not to be curious when you notice a sea shell moving about, with legs and feelers protruding.
While other crustaceans scamper, bury, and hide; not hermit crabs—they are slowly dragging their appropriated spiral shell houses along—which makes them easy to get to know.
To be able to grow they need to change shells to bigger and better regularly. It’s their habit of trading or even stealing shells from other hermits and their gregarious nature that is so fascinating.
There’s about 500 hermit crab species world wide and many live for over 20 years. In Australia you are most likely to meet the two land based varieties: the pale brown “Aussie crab” found along the far north coastline, or the “Red Hermit crab” which is abundant on coral cays on the GBR and Coral sea.
Under the water, it’s a similar story. Small snails would seem to be slowly walking across the bottom, but it’s the intertidal species of Hermits, usually the hairy legged varieties that you are seeing.
Like their land based cousins they have a soft abdomen that is coiled in the same direction as a typical snail shell. Usually found in tidal pools but have been seen as deep as 100m. They are often close to gastropods, whose shells they use. Their enemies include seabirds, fish, octopus and other crabs.
For the naturalist’s within, their plodding nature makes them a wonderful target to study.
Tony is a very knowledgeable enthusiast and loves to chat about this topic.