''Chaunax'', variously known as coffinfishes, gapers, or frogmouths, is a genus of marine

ray-finned fishes Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class (biology), class of Osteichthyes, bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built ...

. It is one of two genera belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Chaunacidae, the sea toads. They are found in tropical and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

oceans around the world, typically in deep water.

Taxonomy

Sea toad genus Chaunax Mona Canyon 13 April 2015

''Chaunax'' was first proposed as a

monospecific genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

in 1846 by the English

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

Richard Thomas Lowe Richard Thomas Lowe (1802–1874) was an English botanist, ichthyologist, malacologist, and clergyman. In 1825 he graduated from Christ's College, Cambridge, and in the same year he took holy orders. In 1832 he became a clergyman in the Madeira ...

when he described ''Chaunax pictus'' as a new species from

Madeira Madeira ( ; ), officially the Autonomous Region of Madeira (), is an autonomous Regions of Portugal, autonomous region of Portugal. It is an archipelago situated in the North Atlantic Ocean, in the region of Macaronesia, just under north of ...

. There are three

species group In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

s within the genus: ''C. pictus'', containing three

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

; ''C. abei'', containing 17 species; and ''C. fimbriatus'', containing nine species. This genus is classified within the family Chaunacidae, the sea toads, one of two genera in that family. The sea toads are placed within the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Chaunacoidei within the

anglerfish The anglerfish are ray-finned fish in the order Lophiiformes (). Both the order's common name, common and scientific name comes from the characteristic mode of predation, in which a modified dorsal Fish fin#Ray-fins, fin ray acts as a Aggressiv ...

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Lophiiformes.

Etymology

''Chaunax'' means "one who gapes", from ''chanos'' meaning "to gape", an allusion to the large, wide mouths of these fishes.

Species

There are currently 29 recognized species in this genus: * '' Chaunax abei'' Y. Le Danois, 1978 * '' Chaunax africanus'' H.-C. Ho &

Last A last is a mechanical form shaped like a human foot. It is used by shoemakers and cordwainers in the manufacture and repair of shoes. Lasts come in many styles and sizes, depending on the exact job they are designed for. Common variations ...

, 2013 (African coffinfish) (African coffinfish) * '' Chaunax albatrossae'' H.-C. Ho & W. C. Ma, 2022 (Albatross frogmouth) * '' Chaunax apus'' Lloyd, 1909 (Southern frogmouth) * ''

Chaunax atimovatae ''Chaunax'', variously known as coffinfishes, gapers, or frogmouths, is a genus of marine Actinopterygii, ray-finned fishes. It is one of two genera belonging to the family (biology), family Chaunacidae, the sea toads. They are found in tropical ...

'' H.-C. Ho & W. C. Ma, 2016 * '' Chaunax brachysomus'' H.-C. Ho, Kawai & Satria, 2015 (Short-body frogmouth) * '' Chaunax breviradius'' Y. Le Danois, 1978 * '' Chaunax endeavouri'' Whitley, 1929 (Furry coffinfish) * '' Chaunax erythraeus'' H.-C. Ho & W. C. Ma, 2022 (Red eyebrow frogmouth) * '' Chaunax fimbriatus'' Hilgendorf, 1879 (Tasselled coffinfish) * '' Chaunax flammeus'' Y. Le Danois, 1979 * '' Chaunax flavomaculatus'' H.-C. Ho, C. D. Roberts & A. L. Stewart, 2013 (Yellowspot frogmouth) * '' Chaunax gomoni'' H.-C. Ho, Kawai & Satria, 2015 (Gomon's frogmouth) * '' Chaunax heemstraorum'' H.-C. Ho & W. C. Ma, 2016 (Heemstra's frogmouth) * '' Chaunax hollemani'' H.-C. Ho & W. C. Ma, 2016 (Holleman's frogmouth) * '' Chaunax latipunctatus'' Y. Le Danois, 1984 * '' Chaunax mulleus'' H.-C. Ho, C. D. Roberts & A. L. Stewart, 2013 (Redshoes frogmouth) * '' Chaunax multilepis'' H.-C. Ho, Meleppura & Bineesh, 2016 (Indian spotted coffinfish) * '' Chaunax nebulosus'' H.-C. Ho & Last, 2013 (Eye-spot coffinfish) * '' Chaunax nudiventer'' H.-C. Ho & K. T. Shao, 2010 (Naked-belly coffinfish) * '' Chaunax obscurus'' H.-C. Ho & W. C. Ma, 2022 (Black-mouth frogmouth) * '' Chaunax penicillatus'' McCulloch, 1915 (Pencil coffinfish) * ''

Chaunax pictus The pink frogmouth (''Chaunax pictus''), or redeye, pink gaper or uniform gaper, is a species of marine ray-finned fish belonging to the family Chaunacidae, the sea toads. This species is found in the Atlantic Ocean. Taxonomy The pink frogmouth ...

'' R. T. Lowe, 1846 (Pink frogmouth) * '' Chaunax reticulatus'' H.-C. Ho, C. D. Roberts & A. L. Stewart, 2013 (Netted frogmouth) * '' Chaunax russatus'' H.-C. Ho, C. D. Roberts & A. L. Stewart, 2013 (Red coffinfish) * '' Chaunax stigmaeus'' Fowler, 1946 (Red-eye gaper) * '' Chaunax suttkusi'' J. H. Caruso, 1989 * '' Chaunax umbrinus'' C. H. Gilbert, 1905 * '' Chaunax viridiretis'' H.-C. Ho & W. C. Ma, 2022 (Green-net frogmouth)

Characteristics

''Chaunax'' sea toads have a rotund, slightly laterally flattened body which tapers to a small rounded

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

. The head is large and globelike with a large oblique mouth and eyes set high on the head. The eyes are covered in transparent skin, resembling a window. The teeth in the mouth are vertical, small, thin, and sharp. There is a single visible dorsal spine, the

illicium ''Illicium'' is a genus of flowering plants treated as part of the family Schisandraceae,

, which is relatively short, sits in an oval-shaped depression on the snout, and is tipped with a tuft of filaments, the esca, or lure. The two other dorsal spines are embedded in the skin. The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

is located on the rear of the body and is supported by 10 or 12 soft rays, while the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

contains 6 or 7 soft rays. The loose, flabby skin has a dense covering of very small denticles. The lateral line is open and runs from the caudal peduncle to the head, with obvious canals connecting to branches under the eye, on the chin, and along the lower flanks. The main part of the lateral line on the upper body contains between 29 and 42 pores, with between 11 and 13 pores on the head. These are mostly rather small species, with the largest being ''C. picus'', with a maximum published

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

of , while the smallest is ''C. breviradius'', which has a maximum published

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

of .

Distribution and habitat

''Chaunax'' anglerfishes are found in all three oceans of the world. They are benthic fishes, found at depths between .

Biology

''Chaunax'' coffinfishes are only distantly related to the

frogfish Frogfishes are any member of the anglerfish family Antennariidae, of the order Lophiiformes. Antennariids are known as anglerfish in Australia, where the term "frogfish" refers to members of the unrelated family Batrachoididae. Frogfishes are f ...

es of the family Antennariidae but have a similar lifestyle as ambush predators, luring prey to within striking distance of their large mouth with the illicium and esca, and using their pectoral and pelvic fins to walk along the bottom. At least one species, ''C. endeavouri'', has been observed inflating its gill chambers by holding onto water. The retained water can inflate their gill chambers so that their bodies become as much as 30% larger, and this water can be retained for lengths of time from 26 seconds up to 4 minutes. These deep-water ambush predators rely on prey coming close enough to strike, which can be infrequent, so the ability to hold water in the gills for longer may be an adaptation to preserve energy while breathing, as well as possibly being a defence against predators. However, the fishes cannot keep the water within the gill chambers if bitten by a predator.

References

{{Taxonbar, from=Q3049570 Chaunacidae Deep sea fish Marine fish genera Ray-finned fish genera Taxa named by Richard Thomas Lowe