Pelagic fishes differ much from one another in their mode of life. The majority are excellent swimmers, which not only can move with great rapidity, but also are possessed of great powers of endurance, and are thus enabled to continue their course for weeks, apparently without the necessity of rest: such are many Sharks, Scombroids, Dolphins, Pilot-fish, Sword-fishes. In some, as in _Dactylopterus_ and _Exocoetus_, the ability of taking flying leaps out of the water is superadded to the power of swimming (Flying-fishes). But in others the power of swimming is greatly reduced, as in _Antennarius_, _Hippocampus_, and Gymnodonts; they frequent places in the ocean covered with floating seaweed, or drift on the surface without resistance, at the mercy of wind and current. The _Echeneis_ or Sucking-fishes attach themselves to other large fish, ships, or floating objects, and allow themselves to be carried about, unless change of climate or want of food obliges them to abandon their temporary carrier. Finally, another class of Pelagic fishes come to the surface of the ocean during the night only; in the day time they descend to some depth, where they are undisturbed by the rays of the sun or the agitation of the surface-water: such are _Brama_, the _Sternoptychidæ_, _Scopelus_, _Astronesthes_; fishes, the majority of which are provided with those extraordinary luminary organs that we find so much developed in the true Deep-sea fishes. Indeed, this last kind of Pelagic fishes forms a passage to the Deep-sea forms.