Frogfishes of the family Antennariidae are typically small, globose anglerfishes easily distinguished from members of allied families by the presence of three well-developed dorsal spines, laterally directed eyes, a large, anterodorsally directed mouth, and a short, laterally compressed body (Pietsch, 1981). They share with other familes of the teleost order Lophiiformes a peculiar and unique mode of feeding that is characterized most strikingly by the structure of the first dorsal spine, which is placed out on the tip of the snout and modified to serve as a luring apparatus.
Frogfishes spend the greater part of their lives squatting on the bottom in shallow to moderately deep water, or as in the case of the single genus Histrio, clinging to floating sargassum. Despite their rather sedentary nature, all are voracious carnivores that wait patiently for smaller fishes or crustaceans to pass by, while they wriggle their bait to entice prey close to their cavernous mouths. Antennariids occur in all major tropical seas of the world except the Mediterranean. The family consists of 12 genera and 43 species.
A lophiiform family unique and derived in having a greatly enlarged third dorsal spine (and associated pterygiophore), as well as a shortened body involving numerous associated specializations but reflected most strikingly by a sigmoid vertebral column (see Pietsch, 1981, figs. 12, 22-35, 41; 1984).
The familiy is further distinguished from all other families of the order by having the following combination of character states: body laterally compressed; mouth strongly oblique to vertical; eyes lateral; posteromedial process of vomer compressed, keel-like; distance between lateral ethmoids considerably less than that between lateral margins of sphenotics; postmaxillary process of premaxilla spatulate; ectopterygoid triradiate; palatine teeth present; dorsal head of quadrate narrow, narrower than ventral margin of metapterygoid; interhyal with a medial, posterolaterally directed process; basihyal present; branchiostegal rays 2 + 4 ; opercle reduced, the width equal to or less than 25% the length of suspensorium; pharyngobranchial I simple (absent in Lophiocharon and Histiophryne); spinous dorsal of 3 cephalic spines; illicial pterygiophore and pterygiophore of third dorsal spine with highly compressed, blade-like dorsal expansions; illicial bone not retractable within an illicial cavity; 3 pectoral radials; pectoral-fin lobe not membranously attached to rays of pelvic fin; pectoral fin single, the rays not membranously attached to side of body; pelvic fin of 1 spine and 5 rays. (Pietsch, 1981, 1984)
Body short, globose, laterally compressed; mouth large, the upper and lower jaws with 2-4 more or less irregular rows of small, villiform teeth; opercular opening restricted to a small, elongate, tube-like opening immediately ventral to, or posterior to, base of pectoral fin (prolonged posteriorly, siturated halfway between base of pectoral lobe and anal fin, or reaching base of anal fin, in some species of Antennarius); spinous dorsal fin of 3 cephalic spines, the anteriormost spine (illicium) free and modified as a lure; distinct fleshy bait or esca usually present, but absent in Lophiocharon lithinostomus and Echinophryne; second and third dorsal spines usually more or less erect (laid back and bound down to surface of cranium by skin of head in Histiophryne), usually widely separated from each other and from soft-dorsal (connected to each other and to soft-drosal by skin in Lophiocharon and in some species of Antennarius); posterior end of pterygiophore of illicium usually cylindrical in cross section (dorsoventrally flattened and expanded laterally in Tathicarpus); pectoral lobe elongate, leg-like, usually broadly attached to side of body (free for most of its length in Histrio and Tathicarpus); skin usually coverd with close-set dermal spinules (spinules usually bifurcate, simple in Histiophryne, reduced, minute, or absent in Nudiantennarius and Histrio, absent in Phyllophryne and Rhycherus); cutaneous filaments or appendages nearly always present; mesopterygoid usually absent, present in Antennarius, Nudiantennarius, Antennatus, and Histrio; epural usually absent, present in Antennarius, Nudiantennarius, Antennatus, and Histrio; pseudobranch usually absent, present in Antennarius, Histrio, and Tathicarpus; swimbladder usually present, absent in Kuiterichthys and Tathicarpus.
Antennarius pictus (Shaw & Nodder). © J. Ronsenfeld
Vomer and palatine well-toothed; pharyngobarnchial I, if present (absent in Lophiocharon and Histiophryne), usually toothless (a single tooth-bearing plate present on only right side of 73-mm specimen of Allenichthys examined osteologically); pharyngobranchials II and III well toothed; epibranchials usually toothless (a row of 6-11 teeth present on epibranchial I of Tathicarpus; a single tooth-bearing plate, or small remnants of a tooth-plate, present on epibranchial I of some specimens of Antennarius, Antennatus, Kuiterichthys, Allenichthys, Echinophryne, Phyllophryne, and Rhycherus); ceratobranchials I-IV usually toothless (a single tooth-plate, often reduced to a small remnant, present on ceratobranchial I of Allenichthys, some species of Echinophryne and Rhycherus); ceratobranchial V with 2-6 more or less irregular rows of teeth; hypobranchials II and III usually bifurcate proximally (hypobranchial II often reduced and simple in Kuiterichthys, Allenichthys, Echinophryne, Rhycherus, and Histiophryne); ossified basibranchial only rarely present; vertebrae 18-23, caudal centra 12-18, dorsal rays 10-16, anal rays 6-10, pectoral rays 6-14; usually only 7 innermost rays of caudal fin bifurcate (all rays bifurcate in Antennarius, Antennatus, Allenichthys, Lophiocharon, and Rhycherus; all simple in Tathicarpus).
Color and color pattern highly variable, with two extremes (the entire range of which can be assumed by living individuals of many species during a period of days or weeks, the specimens often changing radically upon preservation); a more common light-color phase with light-tan to yellow, orange, light-brown, or rust background often overlaid with black, brown, pink, or bright-yellow streaks, bars, and/or spots o the head, body, and fins; and a dark-color phase with green, dark-red, dark-brown, to black background with streaks, bars, and/or spots often (but not always) showing through as deeper black, tips of rays of paired fins often white.
Juveniles and adults benthic in 0-300 m, with the single exception of Histrio, which is pelagic in floating sargassum weed; adults of some species attaining a standard length of at least 35 cm; occurring in all major tropical seas of the world except the Mediterranean; 12 genera and 43 species.
Frogfishes are widely distributed in tropical waters of all four major marine faunal realms of the world. By far the majority of the species, however, and all but three of the genera, are confined geographically to the Indo-Australian Archipelago. The family is well represented in the Gulfs of California and Mexico, the Red Sea, and the Persian Gulf, but like all antennarioids it is unknown from the Mediterranean Sea. With the possible exception of Histrio, Antennarius, with its 24 species, is the only circumglobal genus. In the Western Atlantic it ranges from Long Island, New York, to the southern-most coast of Brazil, and in the Eastern Atlantic, form the Azores and the coast of Senegal to South-West Africa. In the Indo-Pacific it ranges from the tip of South Africa and the Red Sea eastward to virtually all oceanic island groups of the South Pacific, and from southern Japan to New Zealand and the tropical waters of Australia. In the eastern Pacific Ocean, Antennarius occurs throughout the Gulf of California to northern-most Peru and the Galápagos Islands, with two records from Isla San Félix, off central Chile.
The genus Antennatus, embracing two species, occurs throughout the tropical Indo-Pacific and Easter Pacific oceans, from East Africa to the Gulf of California, and the coast of Mexico and Central and South America as far south as Colombia and the Galápagos Islands. The monotypic genus Histrio is sympatric with sargassum throughout the Atlantic and Indo-Pacific oceans, with confirmed captures made as far east as Guam in the north and Tonga in the south. Histiophryne occurs from Taiwan, the Philippines, and the Moluccas to the southern coast of Australia. Lophiocharon is found throughout the islands of the Philippines and Indonesia to the northern coast of Western Australia, Northern Territory, Gulf of Carpentaria, and the northeastern coast of Queensland. Tathicarpus is restricted to the southern coast of New Guinea and to Australia about as far south as Perth in the west and Brisbane in the east. Allenichthys occurs only along the shores of Western Australia below about 21° S latitude, with a single record from Port Lincoln, South Australian. Nudiantennarius is known from only four specimens collected off Luzon in the Philippines and at Ambon in the Moluccas, Indonesia. All four remaining genera of the family are restricted to the subtropical coastal waters of Australia and Tasmania below about 30° S latitude.
Evolution and Systematics
Discussion of Phylogenetic Relationships
Pietsch and Groebecker (1987) unsuccessfully attempted to provide a cladistic analysis of the phylogenetic relationships of antennariid genera. In particular, monophyly for the 24 species of the genus Antennarius was not established. Despite considerable effort, they were unable to identify a single clearly derived feature shared by all included taxa. Thus, Pietsch and Grobecker (1987) defined the genus by a suite of what are believed to be primitive features.
Evidence indicates that Antennarius is the least derived member of the family (Pietsch, 1984). All of the known characters of systematic importance found among the 12 genera (at least all of those characters for which relative primitiveness of states could be reasonably hypothesized) appear to be present in Antennarius in the primitive state. Each of the remaining 11 genera possesses at least two, and in some cases as many as nine, apomorphic character states (autapomorhpic states included) that indicate its derived position relative to Antennarius.
Whereas a hypothesis of monophyly for each of the remaining 11 genera can be supported (six genera being monotypic and none containing more than three species), their phylogenetic relationships as elucidated by cladistics remain largely unknown, and they are here sequentially arranged solely on the basis of increasing relative specialization. No group of two or more genera possesses any convincing synapomorphy that does not also occur within lophiiform taxa lying outside the group in question.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:232
Specimens with Barcodes:228
Species With Barcodes:39
Frogfishes, family Antennariidae, are a type of anglerfish in the order Lophiiformes. They are known as anglerfishes in Australia, where 'frogfish' refers to the Batrachoididae. Frogfishes are found in almost all tropical and subtropical oceans and seas around the world, the primary exception being the Mediterranean Sea.
Frogfishes are small, short and stocky, and sometimes covered in spinules and other appendages to aid in camouflage. The camouflage aids in protection from predators and to enables them to lure prey. Many species can change color; some are covered with other organisms such as algae or hydrozoa. In keeping with this camouflage, frogfishes typically move slowly, lying in wait for prey, and then striking extremely rapidly, in as little as 6 milliseconds.
There are few traces of frogfishes in the fossil record, though Antennarius monodi is known from the Miocene of Algeria.
Frogfishes live in the tropical and subtropical regions of the Atlantic and Pacific, as well as in the Indian Ocean and the Red Sea. Their habitat lies for the most part between the 20-degree isotherms, in areas where the surface level water usually has a temperature of 20 C (68 F) or more. They extend beyond the 20-degree isotherms in the area of the Azores, Madeira, and the Canary Islands, along the Atlantic coast of the USA, on the south coast of Australia and the northern tip of New Zealand, coastal Japan, around Durban, South Africa, and at Baja California. The greatest diversity of species is in the Indo-Pacific region, with the highest concentration around Indonesia. In the small Lembeh Strait, north-east of Sulawesi, divers have found nine different species. Frogfish live generally on the ocean floor around coral or rock reefs, at most up to 100 meters (330 ft) deep.
There are a few exceptions to these general limits. The Brackishwater Frogfish is at home in ocean waters as well as brackish and fresh water around river mouths. The Sargassumfish lives in clumps of drifting sargassum, which often floats into the deeper ocean and have been known to take the sargassumfish as far north as Norway.
Frogfishes have a stocky appearance, atypical of fish. Ranging from 2.5–38 cm (1-15 inches) long, their plump, high-backed, non-streamlined body is scaleless and bare, often covered with bumpy, bifurcated spinules. Their short bodies have between 18 and 23 vertebrae and their mouths are upward pointed with palatal teeth. They are often brightly colored, white, yellow, red, green, or black or spotted in several colors in order to blend in with their coral surroundings. Coloration can also vary within one species, making it difficult to differentiate between them.
Rather than typical dorsal fins, the front-most of the three fins is called the illicium or "rod" and is topped with the esca or "lure". The illicium often has striped markings, while the esca takes a different form in each species. Because of the variety of colors even within a single species, the esca and illicium is a useful tool to differentiate among different varieties. Some of them resemble fish, some shrimp, some polychaetes, some tubeworms, and some simply a formless lump; one genus, Echinophryne has no esca at all. Despite very specific mimicry in the esca, examinations of stomach contents do not reveal any specialized predation patterns, for example, only worm-eating fish consumed by frogfishes with worm-mimicking esca. If lost, the esca can be regenerated. In many species the illicium and esca can be withdrawn into a depression between the second and third dorsal fins for protection when they are not needed.
Mimicry and camouflage
The unusual appearance of the frogfish is designed to conceal it from predators and sometimes to mimic a potential meal to its prey. In ethology, the study of animal behavior, this is known as aggressive mimicry. Their unusual shape, color, and skin textures disguise frogfish. Some resemble stones or coral, while others imitate sponges, or sea squirts with dark splotches instead of holes. In 2005, a species was discovered, the striated frogfish, that mimics a sea urchin while the sargassumfish is colored to blend in with the surrounding sargassum. Some frogfish are covered with algae or hydrozoa. Their camouflage can be so perfect, that sea slugs have been known to crawl over the fish without recognizing them.
For the scaleless and unprotected frogfish, camouflage is an important defense against predators. Some species can also inflate themselves, like pufferfish, by sucking in water in a threat display. In aquariums and in nature, frogfish have been observed, when flushed from their hiding spots and clearly visible, to be attacked by clownfish, damselfish, and wrasse, and in aquariums, to be killed.
Many frogfishes can change their color. The light colors are generally yellows or yellow-browns while the darker are green, black, or dark red. They usually appear with the lighter color, but the change can last anywhere from a few days to several weeks. It is unknown what triggers the change.
Frogfishes generally do not move very much, preferring to lie on the sea floor and wait for prey to approach. Once the prey is spotted, they can approach slowly using their pectoral and pelvic fins to walk along the floor. They rarely swim, preferring to clamber over the sea bottom with their fins in one of two "gaits". In the first they alternately move their pectoral fins forward, propelling themselves somewhat like a two-legged tetrapod, leaving the pelvic fins out. Alternately, they can move in something like a slow gallop, whereby they move their pectoral fins simultaneously forward and back, transferring their weight to the pelvic fins while moving the pectorals forward. With either gait, they can only cover short stretches.
In open water, frogfishes can swim with strokes of the tail fin. They also have a kind of jet propulsion that is often used by younger frogfish. It is achieved by rhythmically forcing their breath-water out through their gill openings, which lie behind their pelvic fins.
The sargassum frogfish has adapted fins which can grab strands of sargassum, enabling it to "climb" through the seaweed.
Frogfishes eat crustaceans, other fish, and even each other. When potential prey is first spotted, the frogfish follows it with its eyes. Then, when it approaches within roughly seven body-lengths, the frogfish begins to move its illicium in such a way that the esca mimics the motions of the animal it resembles. As the prey approaches, the frogfish slowly moves to prepare for its attack; sometimes this involves approaching the prey or "stalking" while sometimes it is simply adjusting its mouth angle. The catch itself is made by the sudden opening of the jaws, which enlarges the volume of the mouth cavity up to twelve-fold, pulling the prey into the mouth along with water. The attack can be as fast as 6 milliseconds. The water flows out through the gills, while the prey is swallowed and the esophagus closed with a special muscle to keep the victim from escaping. In addition to expanding their mouths, frogfish can also expand their stomachs to swallow animals up to twice their size.
Slow-motion filming has shown that the frogfish sucks in its prey in just six milliseconds, so fast that other animals cannot see it happen. This is less time than it takes a muscle to contract, so the source of the motion remains unknown.
The reproductive behavior of the normally solitary frogfish is still not fully researched. There are few observations in aquariums and even fewer from the wild. Most species are free-spawning, with females laying the eggs in the water and males coming in behind to fertilize them. Anywhere from eight hours to several days before the egg-laying, the abdomen of the female starts to swell as the eggs absorb water, sometimes as many as 180,000 eggs. The male begins to approach the female around two days before the spawning. It is not known if the spawn is predetermined by some external factor, such as the phase of the moon, or if the male is attracted to a smell or signal released by the female. In all hitherto observed breeding pairs, one partner was noticeably, sometimes as much as ten times, larger than the other. When the gender could be determined, the larger partner was always the female.
During the free-spawning courtship ritual, the male swims beside and somewhat behind the female, nudges her with his mouth then remains near her cloaca. Just before the spawning, the female begins to swim above the ocean floor toward the surface. At the highest point of their swim they release the eggs and sperm before descending back. Sometimes the male pulls the eggs out of the female with his mouth. After mating the partners depart quickly as otherwise the smaller male would likely be eaten. A few species are substrate-spawners, notably the genera Lophiocharon, Phyllophryne, and Rhycherus, which lay their eggs on a solid surface, such as a plant or rock. Some species guard their eggs, a duty assigned to the male in almost all species, while most others do not. Several species practice brood carrying, for example the three-spot frogfish, whose eggs are attached to the male, and those in the genus Histiophryne, whose brood are carried in the pectoral fins.
The eggs are 0.5-1mm (0.02-0.04in) large and cohere in a gelatinous mass or long ribbon, which in Sargassumfish are up to a meter (3.3 ft) long and 16 cm (6 in) wide. These egg masses can include up to 180,000 eggs. For most species, the eggs drift on the surface. After two to five days, the fish hatch and the newly hatched alevin are between 0.8 and 1.6 mm long (0.03 and 0.07 in). For the first few days they live on the yolk sac while their digestive systems continue to develop. The young have long fin filaments and can resemble tiny, tentacled jellyfish. For one to two months they live planktonically. After this stage, at a length of between 15 and 28 mm (0.6-1.1 in), they have the form of adult frogfish and begin their lives on the sea floor. Young frogfish often mimic the coloration of poisonous sea slugs or flatworms.
Hardly any fossil remains of frogfishes have been found. In the north-Italian formation at Monte Bolca, formed from the sedimentation of the Tethys Ocean in the middle Eocene, a three centimeter (1.2 in) fossil named Histionotophorus bassani was initially described as a frogfish, but was later thought to belong to the closely related extant genus Brachionichthys or handfish. In 2005, a fossil from Miocene Algeria, Antennarius monodi, is the first proven fossil frogfish, believed to be most closely related to the extant senegalese frogfish.
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Many public aquariums around the world keep frogfishes. Though they are prized for their unique appearance, they are not easy to keep for a number of reasons. They often refuse food or become very fat when they do accept it. Furthermore, they must usually be kept alone as they will eat anything up to twice their size, including other frogfish, even potential mates. Also, as they can change their coloration, many lose the bright patterns they have initially, especially when kept in empty or more dull-colored tanks as opposed to the bright coral environments that they are used to.
Though frogfish have been observed to spawn in captivity, captive breeding is difficult. It is currently not known how to sex most species without dissection so keeping an appropriate pair together raises problems. Furthermore even if they do spawn, raising fry through the planktonic phase is very difficult because the larval fish require extremely tiny live food and must be protected from other predatory fish.
Frogfishes belong to the order Lophiiformes, commonly known as anglerfish, which is a member of the superorder Paracanthopterygii with four other orders. They belong to the infraclass Teleostei, the bony fishes, in the class Actinopterygii.
Red ocellated frogfish, St. Kitts, A. ocellatus
Longlure frogfish, Bonaire, A. multiocellatus
Painted frogfish, A. pictus
Warty frogfish, A. maculatus
- Arnold, R.J., Harcourt, R. & Pietsch, T.W. (2014). "A New Genus and Species of the Frogfish Family Antennariidae (Teleostei: Lophiiformes: Antennarioidei) from New South Wales, Australia, with a Diagnosis and Key to the Genera of the Histiophryninae". Copeia, 2014 (3): 534–539.
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- Diving with Frogfish Dive the World 2009
- Frogfish Factsheet Shedd Aquarium Explore by Animal 2009
- Lloyd, Robin Crawling fish accepted as new species MSNBC.com
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- Striated Frogfish Florida Museum of Natural History
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- Frogfish spawn on Valentine's Day National Sea Life Center, Birmingham
- G. Carnevale1 & T.W. Pietsch: Filling the gap: a fossil frogfish, genus Antennarius (Teleostei, Lophiiformes, Antennariidae), from the Miocene of Algeria Abstract
- Pietsch and Grobecker, 1987. Frogfishes of the World. Stanford University Press.
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