Among the Teleostei, the family Berycidæ has several representatives in the deep water. They are small fish rarely exceeding four inches in length, with large heavy heads, with functional but small eyes, and an abundant supply of large mucous glands on the skin.
Melamphaes beanii, belonging to this family, has been captured at the enormous depth of 2,949 fathoms.
Bathydraco antarcticus, belonging to the family Trachinidæ, from a depth of 1,260 fathoms, is an example of a true abysmal fish possessing very large eyes.
The Pediculati, the family of the anglers, is represented at depths of over 2,000 fathoms by the interesting form Melanocetus Murrayi. The eyes are very small indeed, the mouth huge and armed with long uneven rasp-like teeth. At the end of the fishing-rod tentacle hanging over the mouth, there is an organ that has been supposed to be capable of emitting a phosphorescent light. This curious modification of the red worm-like bait of the common shallow-water angler into a will-o-the-wisp lantern attracting little fishes to their destruction in the deadly jaws of the Melanocetus is one of the most interesting adaptations that have been brought to light by our study of the deep-sea fauna.
Several species of the family Lycodidæ occur in the abysmal zone, but they do not possess any features that call for special mention in this place.
Fig. 21.—Melanocetus Murrayi, 1,850–2,450 fathoms. (After Günther.)
The family Ophidiidæ contributes very largely to the fish fauna of the abyss. Some of the deep-water genera, such as Neobythites, have a wide bathymetrical distribution extending from 100 fathoms to depths of over 2,000 fathoms, but others, such as Bathyonus, Typhonus, and Aphyonus, only occur in depths of over 1,000 fathoms.
The body is usually elongate and slender, ending in a pointed tail, the head large and heavy, and the eyes, in the genera confined to the abysmal zone, usually so far degenerated that they are not visible at all from the outside.
The Macruridæ form a family that contributes very largely to the deep-sea fauna; no fewer than twenty-six different species are known to occur within the limits of the abysmal zone. Not only do the Macruridæ contribute a large number of different species, but they probably occur, in some districts at any rate, in vast numbers.