Auxis rochei common in the Atlantic, Mediterranean, and Indian Ocean.
Cybium.—The first dorsal continuous, with the spines rather feeble; generally more than seven finlets behind the dorsal and anal. Scales rudimentary or absent. Teeth strong; a longitudinal keel on each side of the tail.
Twelve species from the tropical Atlantic and Indian Ocean; frequenting more the coast-region than the open sea; attaining to a length of four or five feet.
Elacate.—Body covered with very small scales; head depressed; cleft of the mouth moderately wide; no keel on the tail. The spinous dorsal is formed by eight small free spines; finlets none. Villiform teeth in the jaws, on the vomer and the palatine bones.
Elacate nigra, a coast fish common in the warmer parts of the Atlantic and the Indian Ocean.
Echeneis.—The spinous dorsal fin is modified into an adhesive disk, occupying the upper side of the head and neck.
This genus is closely allied to the preceding, from which it differs only by the transformation of the spinous dorsal fin into a sucking organ. The spines being composed of two halves, each half is bent down towards the right and the left, forming a support to a double series of transverse lamellæ, rough on their edges, the whole disk being of an oval shape and surrounded by a membranous fringe. Each pair of lamellæ is formed out of one spine, which, as usual, is supported at the base by an interneural spine. By means of this disk the “Sucking-fishes” or “Suckers” are enabled to attach themselves to any flat surface, a series of vacuums being created by the erection of the usually recumbent lamellæ. The adhesion is so strong that the fish can only be dislodged with difficulty, unless it is pushed forward by a sliding motion. The Suckers attach themselves to sharks, turtles, ships, or any other object which serves their purpose. They cannot be regarded as parasites, inasmuch as they obtain their food independently of their host. Being bad swimmers they allow themselves to be carried about by other animals or vessels endowed with a greater power of locomotion. They were as well known to the ancients as they are to the modern navigators. Aristotle and Aelian mention the Sucker under the name of φθεὶρ, or the Louse; “In the sea between Cyrene and Egypt there is a fish about the Dolphin (Delphinus), which they call the Louse; this becomes the fattest of all fishes, because it partakes of the plentiful supply of food captured by the Dolphin.” Later writers, then, repeat a story, the source of which is unknown, viz. that the “Remora” is able to arrest vessels in their course, a story which has been handed down to our own time. It need not be stated that this is an invention, though it cannot be denied that the attachment of one of the larger species may retard the progress of a sailing vessel, especially when, as is sometimes the case, several individuals accompany the same ship. An account of a somewhat ingenious way of catching sleeping turtles by means of a Sucking-fish held by a ring fastened round its tail, appears to have originated rather from an experiment than from regular practice.
Ten different species are known, of which Echeneis remora and Echeneis naucrates are the most common. The former is short and grows to a length of eight inches only, the latter is a slender fish, not rarely found three feet long. The bulkiest is Echeneis scutata, which attains to a length of two feet; individuals of that size weighing about eight lbs.
The number of pairs of lamellæ varies in the various species, from 12 to 27. The caudal fin of some of the species undergoes great changes with age. In young specimens the middle portion of the fin is produced into a long filiform lobe. This lobe becomes gradually shorter, and the fin shows a rounded margin in individuals of middle age. When the fish approaches the mature state, the upper and lower lobes are produced, and the fin becomes subcrescentic or forked.
[See Günther, “On the History of Echeneis.” Ann. and Mag. Nat. Hist., 1860.]