Seahorses range in size from 1.5 to 35.5 cm (0.6 to 14.0 in).[4] They are named for their equine appearance. Although they are bony fish, they do not have scales, but rather thin skin stretched over a series of bony plates, which are arranged in rings throughout their bodies. Each species has a distinct number of rings. Seahorses swim upright, another characteristic not shared by their close pipefish relatives, which swim horizontally. Razorfish are the only other fish that swim vertically like a seahorse. Unusual among fish, a seahorse has a flexible, well-defined neck. It also sports a coronet on its head, which is distinct for each individual.