Chimaera | Electroreceptive fish

Chimaeras are cartilaginous fishes in the order Chimaeriformes, known informally as ghost sharks, ratfish, spookfish or rabbitfishes. They may be the oldest and most enigmatic groups of fishes alive today. This group of fish is distantly related to sharks but difficult to classify—the two lineages split some 400 million years ago. Since that time chimaera have remained in isolation and retained their electroreceptive abilities.

Chimaeras are tapered fishes with large pectoral and pelvic fins, large eyes, and two dorsal fins, the first preceded by a sharp spine. They have slender tails, from which the name ratfish, applied to some, has been derived. There are about 28 species of chimaeras, ranging in length from about 60 to 200 centimetres (24 to 80 inches) and in colour from silvery to blackish. The species are placed in three families: Chimaeridae (including the species called rabbit fish), characterized by a rounded or cone-shaped snout; Callorhinchidae (elephant fishes), with an unusual, hoe-shaped, flexible snout; and Rhinochimaeridae (long-nosed chimaeras), with an extended, pointed snout.