Anglerfish
From Omnictionary
Anglerfish are bony fish in the order Lophiiformes, named for their characteristic mode of predation, wherein a fleshy growth from the fish's head (the esca) acts as a lure; this is considered analogous to angling.
Anglerfish are both pelagic and benthic fishes of the abyss (e.g. Ceratiidae) and the continental shelf (e.g. the frogfishes Antennariidae and the monkfish/goosefish Lophiidae) respectively. They occur worldwide. Pelagic forms are most laterally compressed whereas the benthic forms are often extremely dorsoventrally compressed (depressed) often with large upward pointing mouths.
Predation
The fish are named for their characteristic method of predation. Anglerfish typically have three long filaments sprouting from the middle of the head; these are the detached and modified three first spines of the anterior dorsal fin. In most anglerfish species, the longest filament is the first (the illicium). This first spine protrudes above the fish's eyes, and terminates in an irregular growth of flesh (the esca) at the tip of the spine. The spine is movable in all directions, and the esca can be wiggled so as to resemble a prey animal, and thus to act as bait to lure other predators close enough for the anglerfish to devour them whole. The jaws are triggered in automatic reflex by contact with the tentacle.
Some deep sea anglerfish of the aphotic zone, may have bioluminescent esca (via bacterial symbiosis).
In most species a wide mouth extends all around the anterior circumference of the head, and both jaws are armed with bands of long pointed teeth, which are inclined inwards, and can be depressed so as to offer no impediment to an object gliding towards the stomach, but to prevent its escape from the mouth. The anglerfish is able to distend both its jaw and its stomach (its bones are thin and flexible) to enormous size, allowing it to swallow prey up to twice as large as its entire body.
Some benthic (bottom-dwelling) forms have arm-like pectoral fins which the fish use to walk along the ocean floor. The pectoral and ventral fins are so articulated as to perform the functions of feet, enabling the fish to move, or rather to walk, on the bottom of the sea, where it generally hides itself in the sand or amongst seaweed. All around cellulite its head and also along the body the skin bears fringed appendages resembling short fronds of seaweed, a structure which, combined with the extraordinary faculty of assimilating the colour of the body to its surroundings, assists this fish greatly in concealing itself in places which it selects on account of the abundance of prey.
