Ratfish The spotted ratfish (Hydrolagus colliei), also known as the shortnose chimera or elephant fish, is certainly an odd-looking animal. Found on the bottom of the North-East Pacific, it is a relative of sharks and rays. The fish has no teeth but instead swallows its prey whole after stunning it by whacking it with its whip-like tail.
This fish grows up to just over 1m in length, but it seems bigger as they are found lying on their side when sleeping, which is their normal position. They are nocturnal animals that are rarely seen by divers in the day, but often spotted at night when they come out to feed. When approached at night by divers, these fish will remain motionless (if not asleep) or quickly swim away - unless you get too close; at which point the fish will whack you with its tail.
These large tails are mainly used for swimming, but can also be employed as a weapon to stun prey or ward off would-be predators. Known predators of this fish are the Pacific sleeper shark ( Somniosus pacificus) and the salmon shark ( Lamna ditropis). Both of these sharks are also seen sleeping motionless on the seafloor, so spotted ratfish may whack them before they can attack. The chimera has no other natural enemies because of its lack of teeth and large size.
The fish is named for its long pointed tail which gives it a rat-like appearance. This appendage also aids the fish when it swims. Its tail makes up about a quarter of its total length. The other parts of this large fish have been compared to that of a seahorse or sea serpent, with a long head and snout resembling an elephant's trunk (hence another common name, "elephant fish").
The spotted ratfish has smooth and scaleless skin; the only scales on its body are those on the head, which can be blue or grey. The eyes of this fish are set high on its head and bulge like those of an amphibian. These unusual eyes give the animal good binocular vision, which is necessary as their habitat is full of rocks and boulders. You can (rarely) see spotted ratfish at depths down to 500m, but they are most commonly seen by divers between 20m and 80m deep on rocky reefs, in kelp forests, or over sand flats. These fish are not targeted commercially, but the eggs of this species are harvested as a delicacy in Japan.