Horseshoe Leatherjacket

This species of Leatherjacket is sometimes seen on Three Mile Reef off the coast of Perth, where this shot was taken. Leatherjackets have a large poisonous spine just behind its head, and care has to be taken when handling them. The spine is usually folded down, as in this case, but when the fish becomes agitated it raises the spine. The markings on its side make it easy to guess how it got its name.