Iron Crab

Adults average 57 mm (2.2 in) in size with a flattened oval-shaped carapace that is wide in the front with blunt lobed edges. This can be a rusty red to chocolate brown colour with light mottling. Underside may be a paler cream colour. The antennae are dark red to brown. Claws are large with a smooth texture. Fingers may be black or brown in colour. Walking legs are pale red with golden setae or hairs.

It is common around the North Island of New Zealand. Found in Australia from Eastern Victoria to New South Wales, on Flinders Island and the Kent Group. It is also found on Lord Howe Island and Norfolk Island.

The black finger crab is a scavenger. It feeds on snails, half-crabs and hermit crabs. It is known to chip away at the shells of larger snails before grasping the animal with its mouth-parts. Smaller snails are crushed by the crab's large claws. It also feeds on limpets and chitons by using the tip of its claw to remove them from a rock.

It will spread its claws when started or threatened.