This obscure, deep-sea family has just six species assigned to it. Some scientists do not treat this family separately, but lump its members with the chimaera family, Chimaeridae. Regardless of their taxonomic position, these species share the bizarre and unusual appearance of all chimaeras including an elongate body, relatively large eyes, and a protruding snout. This latter feature, along with the obvious, protruding bony "teeth plates" that resemble large incisors give the group its alternate common name, rabbitfishes. The long snout is a sensory organ, and as such is well-endowed with both chemical and electrical sensors. It is believed that these senses are used to detect prey and/or mates. When the latter resource is acquired, male longnose chimaeras hold onto their prize with claspers on their heads, which grasp the female's pectoral fin during mating.
All chimaeras, longnose or otherwise, are primitive fishes that are related
to the sharks, and share several features with them, such as scaleless skin,
and eggs that are encapsulated in horny packages. Longnose chimaeras are characterized
by a fleshy gill cover which overlays four gill slits, and a venomous spine
that stands erect on the first of the two dorsal fins. These fishes are not
good swimmers, and are thought to feed on invertebrates and various other fishes,
presumably those that they are capable of catching. They inhabit deep waters,
down to 2600 m.
One species of longnose chimaera occurs in the Arctic:
Haeckel's chimaera (Harriotta haeckeli)