Anglerfish
Overview
Anglerfishes are members of the teleost order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Lophiiformes . They are bony fishes
Osteichthyes
Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...

 named for their characteristic mode of predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

, wherein a fleshy growth from the fish's head (the esca or illicium) acts as a lure; this is considered analogous to angling
Angling
Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...

.

Some anglerfishes are pelagic (live in the open water), while others are benthic (bottom-dwelling). Some live in the deep sea (e.g., Ceratiidae
Ceratiidae
Sea devils are a family of deep-sea anglerfish otherwise known as Ceratiidae from the Greek keras, "horn", referring to the bioluminescent lure that projects from the fishes' forehead....

) and others on the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 (e.g., the frogfishes Antennariidae and the monkfish/goosefish Lophiidae).
Discussions
Encyclopedia
Anglerfishes are members of the teleost order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Lophiiformes . They are bony fishes
Osteichthyes
Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...

 named for their characteristic mode of predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

, wherein a fleshy growth from the fish's head (the esca or illicium) acts as a lure; this is considered analogous to angling
Angling
Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...

.

Some anglerfishes are pelagic (live in the open water), while others are benthic (bottom-dwelling). Some live in the deep sea (e.g., Ceratiidae
Ceratiidae
Sea devils are a family of deep-sea anglerfish otherwise known as Ceratiidae from the Greek keras, "horn", referring to the bioluminescent lure that projects from the fishes' forehead....

) and others on the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 (e.g., the frogfishes Antennariidae and the monkfish/goosefish Lophiidae). They occur worldwide. Pelagic forms are most lateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

ly (sideways) compressed whereas the benthic forms are often extremely dorsoventrally compressed (depressed) often with large upward pointing mouths.

Evolution

A mitochondrial genome phylogenetic study suggested that anglerfishes diversified in a short period of the early to mid Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

, between 130 and 100 million years ago.

Predation

The fish are named for their characteristic method of predation. Anglerfish typically have at least one long filament sprouting from the middle of the head; these are the detached and modified three first spines of the anterior dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

. 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. Watch an example of an anglerfish (Antennarius pictus) feeding: Anglerfish Feeding.

Some deep-sea anglerfishes of the bathypelagic zone emit light from their escas to attract prey. This bioluminescence
Bioluminescence
Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...

 is a result of symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 with bacteria. The bacteria may enter the esca from the seawater through small pores; however, this is speculative and the mechanism by which ceratioids harness these bacteria is unknown. In the confines of the esca, they can multiply until their density is such that their collective glow is very bright.

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 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
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...

 (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 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, camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

 the fish in areas abundant with prey.

Reproduction

Some anglerfishes, like those of the Ceratioid group (Ceratiidae
Ceratiidae
Sea devils are a family of deep-sea anglerfish otherwise known as Ceratiidae from the Greek keras, "horn", referring to the bioluminescent lure that projects from the fishes' forehead....

, or sea devils), employ an unusual mating method. Because individuals are presumably locally rare and encounters doubly so, finding a mate is problematic. When scientists first started capturing ceratioid anglerfish, they noticed that all of the specimens were females. These individuals were a few centimetres in size and almost all of them had what appeared to be parasites attached to them. It turned out that these "parasites" were highly reduced male ceratioid
Ceratiidae
Sea devils are a family of deep-sea anglerfish otherwise known as Ceratiidae from the Greek keras, "horn", referring to the bioluminescent lure that projects from the fishes' forehead....

s.

At birth, male ceratioids are already equipped with extremely well developed olfactory organs
Olfactory system
The olfactory system is the sensory system used for olfaction, or the sense of smell. Most mammals and reptiles have two distinct parts to their olfactory system: a main olfactory system and an accessory olfactory system. The main olfactory system detects volatile, airborne substances, while the...

that detect scents in the water. The male ceratioid lives solely to find and mate with a female. They are significantly smaller than a female angler fish, and may have trouble finding food in the deep sea. Furthermore, the growth of the alimentary canals of some males becomes stunted, preventing them from feeding. These features necessitate his quickly finding a female anglerfish to prevent death. The sensitive olfactory organs help the male to detect the pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...

s that signal the proximity of a female anglerfish. When he finds a female, he bites into her skin, and releases an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that digests the skin of his mouth and her body, fusing the pair down to the blood-vessel level. The male then slowly atrophies
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...

, first losing his digestive organs, then his brain, heart, and eyes, and ends as nothing more than a pair of gonads, which release sperm
Spermatozoon
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...

 in response to hormones in the female's bloodstream indicating egg
Ovum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...

 release. This extreme sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 ensures that, when the female is ready to spawn, she has a mate immediately available. Multiple males can be incorporated into a single female.

The spawn of the anglerfish of the genus Lophius
Lophius
Members of the genus Lophius, also sometimes called monkfish, goosefish, fishing-frogs, frog-fish, and sea-devils, are well known off the coasts of Europe generally, the grotesque shape of its body and its singular habits having attracted the attention of naturalists of all ages...

consists of a thin sheet of transparent gelatinous material 0.6 or 0.9 metres (2 or 3 feet) wide and 7.6 to 9 metres (25–30 feet) long. The eggs in this sheet are in a single layer, each in its own cavity. The spawn is free in the sea. The larvae are free-swimming and have the pelvic fins elongated into filaments. Such an egg sheet is rare among fish.

Human consumption

One family Lophiidae is of commercial interest with fisheries found in the in north-western Europe, eastern North America, Africa and the Far East. In Europe and North America, the tail meat of fish of the genus Lophius
Lophius
Members of the genus Lophius, also sometimes called monkfish, goosefish, fishing-frogs, frog-fish, and sea-devils, are well known off the coasts of Europe generally, the grotesque shape of its body and its singular habits having attracted the attention of naturalists of all ages...

, known as goosefish (North America) or monkfish, is widely used in cooking, and is often compared to lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...

 tail in taste and texture. In Asia, especially Korea and Japan, it is a delicacy.

Threats

Northwest European Lophius
Lophius
Members of the genus Lophius, also sometimes called monkfish, goosefish, fishing-frogs, frog-fish, and sea-devils, are well known off the coasts of Europe generally, the grotesque shape of its body and its singular habits having attracted the attention of naturalists of all ages...

spp. are listed by the ICES
International Conference on Environmental Systems
The International Conference on Environmental Systems, or ICES , is an annual technical conference focusing on human spaceflight technology and space human factors...

 as "outside safe biological limits." Additionally, anglerfish are known to occasionally rise to the surface during El Niño, leaving large groups of dead anglerfish floating on surface.

In 2010, Greenpeace
Greenpeace
Greenpeace is a non-governmental environmental organization with offices in over forty countries and with an international coordinating body in Amsterdam, The Netherlands...

 International added the American angler (Lophius americanus
Lophius americanus
Lophius americanus is a monkfish in the family Lophiidae, also called goosefish, American anglerfish, all-mouth or fishing frog. It is native to the eastern coast of North America...

), the angler (Lophius piscatorius
Lophius piscatorius
The angler, also sometimes called fishing-frog, frog-fish or sea-devil, Lophius piscatorius, is a monkfish in the family Lophiidae. It is found in coastal waters of the northeast Atlantic, from the Barents Sea to the Strait of Gibraltar, the Mediterranean and the Black Sea...

) and the black-bellied angler (Lophius budegassa) to its seafood red list. The Greenpeace International seafood red list is a list of fish commonly sold worldwide which have a very high likelihood of being sourced from unsustainable fisheries.

Classification

FishBase
FishBase
FishBase is a comprehensive database of information about fish species . It is the largest and most extensively accessed online database on adult finfish on the web...

, Nelson, and Pietsch list eighteen families, but ITIS
Itis
Itis may refer to* Integrated Taxonomic Information System, a partnership designed to provide consistent and reliable information on the taxonomy of biological species...

 lists only sixteen. The following taxa have been arranged to show their evolutionary relationships.
  • Suborder Lophioidei
    • Lophiidae (goosefish
      Goosefish
      Monkfish are a family, Lophiidae, of anglerfishes. They are found in the Arctic, Atlantic, Indian and Pacific Oceans where they live on sandy and muddy bottoms of the continental shelf and continental slope, at depths in excess of ....

      es or monkfish
      Monkfish
      Monkfish is the English name of a number of types of fish in the northwest Atlantic, most notably the species of the anglerfish genus Lophius and the angelshark genus Squatina...

      es)
  • Suborder Antennarioidei
    • Antennariidae (frogfish
      Frogfish
      Frogfishes, family Antennariidae, are a type of anglerfish in the order Lophiiformes. They are known as anglerfishes in Australia, where 'frogfish' refers to a different type of fish...

      es)
    • Tetrabrachiidae (four-armed frogfishes)
    • Brachionichthyidae (handfish
      Handfish
      Handfish are anglerfish in the family Brachionichthyidae, a group which comprises five genera and fourteen extant species.They are small bottom-dwelling marine fish found in coastal waters of southern Australia and Tasmania. Their skin is covered with denticles , giving them the name warty anglers...

      es)
    • Lophichthyidae (Boschma's frogfish — monotypic)
  • Suborder Chaunacoidei
    • Chaunacidae (sea toad
      Sea toad
      Coffinfish are a family, Chaunacidae, of deep-sea anglerfishes.They are bottom-dwelling fishes found on the continental slopes of the Atlantic, Indian and Pacific Oceans, at depths of up to ....

      s)
  • Suborder Ogcocephaloidei
    • Ogcocephalidae
      Ogcocephalidae
      Ogcocephalidae is a family of bottom-dwelling, specially adapted fish. They are sometimes referred to as batfishes or anglerfishes. They are found in deep, lightless waters of the Atlantic, Indian and western Pacific Oceans....

       (batfishes)
  • Suborder Ceratioidei (deepsea families)
    • Centrophrynidae (prickly seadevils — monotypic)
    • Ceratiidae
      Ceratiidae
      Sea devils are a family of deep-sea anglerfish otherwise known as Ceratiidae from the Greek keras, "horn", referring to the bioluminescent lure that projects from the fishes' forehead....

       (warty seadevils)
    • Himantolophidae (footballfish
      Footballfish
      The footballfish are a family, Himantolophidae, of globose, deep-sea anglerfishes found in tropical and subtropical waters of the Atlantic, Indian, and Pacific Ocean...

      es)
    • Diceratiidae (doublespine seadevils)
    • Melanocetidae (black seadevil
      Black seadevil
      Black seadevils are small, deep-sea lophiiform fish comprising the family Melanocetidae. There are five known species , all within the genus Melanocetus...

      s)
    • Thaumatichthyidae (wolf-trap seadevils)
    • Oneirodidae
      Oneirodidae
      The dreamers are a family, Oneirodidae, of deep-sea anglerfishes in the order Lophiiformes. They are the largest and most diverse group of deep-sea anglerfish, and also the least well-known with several genera represented by only one, two, or three female specimens. They are found in deep,...

       (dreamers)
    • Caulophrynidae (fanfin seadevils)
    • Neoceratiidae (needlebeard seadevil — monotypic)
    • Gigantactinidae (whipnose seadevils)
    • Linophrynidae (leftvent seadevils)

External links

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