The Blue Swimmer Crab stay buried under sand or mud most of the time, but when hey come out (usually during the night), you can easily recognize them by their bright blue colour with white spots (males) or a green/brownish colour (females). They usually come out to feed during high tide to feed on various organisms such as bivalves, fish and macroalgae. They are excellent swimmers, largely due to a pair of flattened legs that resemble paddles. They are very territorial and will move into defense-position when you hover above them. They can grow up to approximately 20 cm (8 inch) in width.