Iron Crab

Ozius deplanatus

The iron crab, also known as the black finger crab, is a crustacean found in the coastal waters of New Zealand and Australia. It is particularly common around the North Island of New Zealand and in regions of Australia from Eastern Victoria to New South Wales, including Flinders Island, the Kent Group, Lord Howe Island, and Norfolk Island. This crab is typically found in the intertidal zone, residing under boulders and among stones on sheltered rocky and gravel shores. The iron crab has a distinctive appearance with a flattened oval-shaped carapace that measures around 57 mm in size. Its carapace is wide at the front with blunt lobed edges and can vary in color from rusty red to chocolate brown, often with light mottling. The underside of the crab may be a paler cream color. Its antennae are dark red to brown, and its large claws, which have a smooth texture, can have black or brown fingers. The walking legs are pale red and feature golden setae or hairs. As a scavenger, the iron crab feeds on a variety of prey including snails, half-crabs, hermit crabs, limpets, and chitons. It employs its large claws to crush smaller snails, while it uses the tips of its claws to pry limpets and chitons from rocks. The crab's diet also involves chipping away at the shells of larger snails to access the animal inside. When threatened, the iron crab is known to spread its claws as a defensive posture.