The Sponge Decorator Crab (Hyastenus elatus) belongs to the Spider Crab family Majidae. Decorator crabs have triangular or occasionally rounded carapaces covered by spines, hairs and knobs. The Sponge Decorator Crab is identified by its pear shaped carapace with two long rostral projections that are nearly as long as the body and two shorter projections from the side.
The Sponge Decorator Crab is distributed around tropical Australia from Fremantle on the west coast north around to Shellharbour on the east coast. It is also found in other parts of the west Pacific including Indonesia and Papua New Guinea. It lives in sponge gardens, especially in estuaries and coastal bays. During the day divers often don’t notice them as they hide at the base of sponges but they become more active at night and can be found sitting on top of the sponges. They can be found from 1 metre down to 54 metres. The Sponge Decorator Crab attaches pieces of sponge to its body, which grow around the carapace and it’s legs. The maximum size the carapace grows to is approximately 8cm.
