''Thaumatichthys'', the wonderfish or trapjaw anglerfish, is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

deep-sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low tempe ...

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 ...

in the family

Thaumatichthyidae Thaumatichthyidae, the wolftrap anglers or wolftrap seadevils, is a small family of marine ray-finned fishes, classified within the suborder Ceratioidei, the deep-sea anglerfishes. They have distinctive upper jaws with movable premaxillaries t ...

, with three known

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), ...

. Its

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

means "wonder-fish" in

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

;

oceanographer Oceanography (), also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology. It is an Earth science, which covers a wide range of top ...

Anton Bruun described these fishes as "altogether one of the oddest creatures in the teeming variety of the fish world." In contrast to other anglerfishes, the

bioluminescent Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...

lure (called the "esca") of ''Thaumatichthys'' is located inside its cavernous

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

. They are worldwide in distribution and are ambush

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s living near the

ocean floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

Taxonomy

The first specimen of ''Thaumatichthys'' was collected by an

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, p ...

expedition in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

in 1908 and given the species name ''pagidostomus'' ("trap-mouthed"). A subsequent specimen from the north Atlantic was placed by Regan and Trewavas (1932) into a new genus, ''Amacrodon'', based on differences in

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

. Bruun assigned a specimen collected by the Galathea Expedition of 1950–52 to a third genus, ''Galatheathauma'' ("Galathea's wonder"), as it was much larger than the previous specimens. However, a later examination of the then-32 known specimens showed that these differences were attributable to age, and thus there was only one valid genus, ''Thaumatichthys'', with three species. The closest relative of ''Thaumatichthys'' is ''

Lasiognathus ''Lasiognathus'', the wolftrap anglerfish, is a genus of deep-sea anglerfish in the family Thaumatichthyidae, with six species known from the Atlantic and Pacific Oceans. Like its sister genus ''Thaumatichthys'', it is distinct from other angle ...

'', which also possesses enlarged, hinged premaxillaries, denticles on the esca, and a branched upper operculum. There are also significant differences between the two genera though, and ''Lasiognathus'' shares many more traits with the family

Oneirodidae Oneirodidae, the dreamers are a family of marine ray-finned fishes belonging to the order Lophiiformes, the anglerfishes. These fishes are deepwater fishes found in the Atlantic, Indian and Pacific Oceans, and it is the most diverse family of f ...

(in which it was formerly placed) than does ''Thaumatichthys''.Pietsch, T.W. (2005)
Thaumatichthyidae. Wolftrap Seadevils.
''The Tree of Life Web Project.'' Retrieved on December 7, 2008.

Species

There are currently three recognized species in this genus: * ''

Thaumatichthys axeli ''Thaumatichthys'', the wonderfish or trapjaw anglerfish, is a genus of deep-sea anglerfish in the family Thaumatichthyidae, with three known species. Its scientific name means "wonder-fish" in Greek; oceanographer Anton Bruun described these fi ...

'' Bruun, 1953 * '' Thaumatichthys binghami'' A. E. Parr, 1927 * ''

Thaumatichthys pagidostomus ''Thaumatichthys pagidostomus'' is a species of wonderfish found in the Indian and Atlantic Oceans at a depth of around . This species grows to a length of TL. This species has relatively longer premaxillaries than the other species (measur ...

'' H. M. Smith & Radcliffe, 1912

Distribution and habitat

''Thaumatichthys'' is known from

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

ic waters worldwide. ''T. pagidostoma'', the first species to be discovered, is only known from a single specimen caught at a depth of 1,440 m in the

Gulf of Tomini The Gulf of Tomini (), also known as the Bay of Tomini, is the equatorial gulf which separates the Minahassa (Northern) and East Peninsulas of the island of Sulawesi (Celebes) in Indonesia. The Togian Islands lie near its center. To the east ...

off

Sulawesi Sulawesi ( ), also known as Celebes ( ), is an island in Indonesia. One of the four Greater Sunda Islands, and the List of islands by area, world's 11th-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Min ...

. ''T. axeli'' occurs in the eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, while ''T. binghami'' is found in and around the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

Larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e that could not be referred to species have also been found off the

Gulf of Guinea The Gulf of Guinea (French language, French: ''Golfe de Guinée''; Spanish language, Spanish: ''Golfo de Guinea''; Portuguese language, Portuguese: ''Golfo da Guiné'') is the northeasternmost part of the tropical Atlantic Ocean from Cape Lopez i ...

in the southern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

and in the southern

Mozambique Channel The Mozambique Channel (, , ) is an arm of the Indian Ocean located between the Southeast African countries of Madagascar and Mozambique. The channel is about long and across at its narrowest point, and reaches a depth of about off the coa ...

in the eastern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

. Uniquely amongst deep-sea anglerfish, adult ''Thaumatichthys'' are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

in nature; ''T. binghami'' and ''T. pagidostomus'' are found on the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

between 1,000–2,000 m, while ''T. axeli'' is found in the

abyssal zone The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word ''abyss'' comes from the Greek word (), meaning "bottomless". At depths of , this zone remains in perpetual darkness. It covers 83% of the total area ...

at about 3,600 m.

Description

As with most other deep-sea anglerfishes, ''Thaumatichthys'' shows extreme

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

with the

female An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and ...

s much larger and different in

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

from the

male Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...

s. Female ''Thaumatichthys'' are characterized by a long, broad, flattened

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

with enlarged premaxillaries on the

upper jaw In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillar ...

that overhang the relatively short

lower jaw In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. The premaxillaries are hinged with the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

in such a way that they can be moved down to enclose the lower jaw in a manner similar that of a

Venus flytrap The Venus flytrap (''Dionaea muscipula'') is a carnivorous plant native to the temperate and subtropical wetlands of North Carolina and South Carolina, on the East Coast of the United States. Although various modern hybrids have been created ...

. The outer margin of the premaxillaries bear six rows of long, conical, recurved

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

; the teeth in the lower jaw are much shorter. The number and length of the teeth increases as the fish grows. The distinctive lure of ''Thaumatichthys'' is achieved by an "upside-down" orientation of the illicium (the "fishing rod"): its base is embedded in the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

fold connecting the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

ends of the premaxillaries, and the short illicium projects down and back so that the esca at the tip hangs down from the roof of the mouth. The escal bulb terminates in a pair of forked tendrils and bears varying numbers of lateral lobes and a single curved denticle. The size of the transparent window in the bulb can be adjusted to change the amount of light emanating from the lure. The

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s are tiny and placed close to the corners of the mouth. There are numerous black

papilla Papilla (Latin, 'nipple') or papillae may refer to: In animals * Papilla (fish anatomy), in the mouth of fish * Papilla (worms), small bumps on the surface of certain worms * Basilar papilla, a sensory organ of lizards, amphibians and fish * ...

e with white tips, resembling those of the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

(and likely belonging to the same sensory system), inside the mouth. The body is fairly slender and depressed for a deep-sea anglerfish, with a relatively well developed

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 ...

. The

fin ray 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 b ...

s number 4 in 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 ...

, 7 in the

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 ...

, 6–7 in the

, and 14–16 in the

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s. The upper part of the operculum is divided into 5–13 radiating branches. The

is velvet black or dark brown, with numerous small spines on the lower part of the head and body. The one specimen of ''T. pagidostomus'' measured 6 cm long, the largest known specimen of ''T. binghami'' measured 29 cm long, and the largest specimen of ''T. axeli'' measured 36.5 cm long. The males are small and slender, with greatly enlarged olfactory organs, long hooked denticles at the tips of the jaws, and no esca. The skin is a uniform dark brown with small spines throughout. As the male matures, the body and head become less deep and the jaws become more prolongated. The largest known male specimen measured 45 mm long.

Biology and ecology

The unusual jaw mechanism and esca of ''Thaumatichthys'' has been described as a "living mouse-trap with bait". The premaxillaries on either side of the upper jaw are able to rotate nearly 180° down to trap prey attracted by the luminescent lure; this closing action is effected by large, extremely well developed upper jaw muscles. Muscles in the illicium allow the esca to be swung forward and backward, so as to better entice prey inside the mouth. The upper jaw mechanism enables prey to be captured without the lower jaw, which can remain moving for the purposes of

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...

. Despite this highly specialized predatory apparatus however, examination of the

stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...

contents of a '' T. binghami'', the only specimen with stomach contents, revealed

sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...

s (being three well preserved '' Benthodytes typica'' measuring ) as well as

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

matter (being a piece of ''

Sargassum ''Sargassum'' is a genus of brown macroalgae ( seaweed) in the order Fucales of the Phaeophyceae class. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and ...

'' and other indeterminate plant matter), suggesting that these fishes are

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s, though these may have been incidentally swallowed along with the sea cucumbers, the fish swallowing anything edible. It is unknown whether male ''Thaumatichthys'' are

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

. The structure of the jaws in mature males suggests that feeding is impaired after metamorphosis. The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e are

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

like those of other deep-sea anglerfishes, and are found at depths of no more than 100 m. As the larvae grow and approach

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

, they descend deeper until they reach the bottom. The larvae can be identified by their divided operculum and a subdermal

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

layer that covers the entire head and body. The species differ as follows: *''

'' Both this species and ''T. binghami'' have relatively shorter premaxillaries, at 23.5–27% of

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 ...

. The esca of this species has a single pair of lateral lobes that are enlarged into tapering filaments in the largest individuals, and the uppermost median appendage on its esca is

wart Warts are non-cancerous viral growths usually occurring on the hands and feet but which can also affect other locations, such as the genitals or face. One or many warts may appear. They are distinguished from cancerous tumors as they are caus ...

-like and not tapering. *'' Thaumatichthys binghami'' This species is similar to ''T. axeli'', except that its esca bears 2–3 pairs of lateral lobes that are elongated into tapering filaments in the largest individuals, and the uppermost medial appendage on the esca is

finger A finger is a prominent digit (anatomy), digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities (i.e. hands) such as humans and other primates. Most tetrapods have five digits (dactyly, pentadact ...

-like and tapering. *''

'' This species has relatively longer premaxillaries than the other species (measuring 33% of

), and the anterior premaxillary teeth are long.

References

{{Taxonbar, from=Q2712927 Thaumatichthyidae Marine fish genera Taxa named by Hugh McCormick Smith Taxa named by Lewis Radcliffe