Angler fish, also known as angler fish, are one of the strange-looking bony fish belonging to the order Lophiiformes and more than 15 families. The exact number of families is still controversial, some group 18 families under the same order while others identify 16 families. The name angler fish is given with reference to the fleshy outgrowth present in the head, which is used for luring its prey. This predation is quite similar to angling, and hence the name.
One of the most interesting angler fish facts is the mode of feeding which is different in males and females. The fishing pole like structure on the head, which serves as a lure, is found only in females. Males do not exhibit any such features and they survive just to mate for reproduction. Besides their weird predation method, angler fish also inhabit at the most inhospitable regions.
Angler fish are probably the ugliest looking creatures identified till date. Gray or dark brown in color, they are equipped with characteristic features which help them adapt to the habitat and surrounding conditions. A majority of the angler fish species have a wide mouth that runs along the entire anterior portion. The jaws are equipped with sharp teeth that point inwards. The ability to expand the mouth and the stomach enable these fish to swallow prey that is twice as large as their body size.
Different species of this fish harbor at varying depths. Some are pelagic, dwelling in the open seas; while other species are benthic, living at the bottom of the sea. The free-swimming fish have a laterally compressed body, while the bottom dwellers are dorsoventrally compressed to suit to their habitats. Those living at the sea bottom also bear pectoral fins that resemble hand appendages, which are used for walking on the sea or ocean floor.
As of now, more than 200 species of angler fish are identified, most of which are found living in the Antarctic and Atlantic oceans at a depth of 2-500 meters. The deep sea angler fish habitat is believed to be about 3,000 feet (914 meters) below the water surface. Scientifically named as Melanocetus johnsoni, this species is adapted to the dark sea bottom, where sunlight cannot reach. Also, the water is about near freezing temperature. Consequently, at such depths, the food is scarce and these fish do not feed every day.
The species that belong to the family Antennariidae have habitats in shallow waters; whereas those classified under the family Ogcocephalidae (e.g. batfish) are found in shallow and deep waters. It is claimed that species belonging to the Chaunacidae family (e.g. sea toads) and Lophiidae family (e.g. goosefishes) dwell in deep waters. Since most angler fish live in deep oceans, it is very difficult for marine biologists to study their habitat, feeding, reproduction, and other aspects.
To remain camouflaged in their habitat and while searching for food, angler fish also possess seaweed-like fringes all over their head and body. These incredible fish are a classic example of how creatures adapt to the deepest oceans with fascinating characteristics, irrespective of the scarcity of light and food in the habitat.