The population trends of Anoplogaster cornuta have not been documented. Thus, the potential conservation and management needs of this species are unknown.
Adult and juvenile fangtooths are so morphologically dissimilar that they were believed to be separate species in the 1800s. In addition to differences in their physical appearance, they also consume different prey. Juveniles begin to look like adults after reaching approximately 8 cm in length, and they typically grow to 17 cm in length, with a maximum recorded length of 18 cm, although other sources report a maximum length of 16 cm. Length at reproductive maturity has been reported to be approximately 13 cm. Individuals are found at different depths during different stages of their life cycle, with larvae occuring closer to the surface and adults occuring at depths of up to 5000 m. However, overlap of habitats with respect to depth does occur at various stages of maturity.
Anoplogaster cornuta is found at different depths during various stages of its life cycle and occupies a wide range of temperatures throughout its life. Juveniles may be captured at relatively shallow depths of 45 m in the tropics, where temperatures can rise above 15ºC. This suggests that while they are a stenothermal species with adults often captured at depths with temperatures between 4ºC and 6ºC, adults may be able for survival across a much broader thermal range.
There are no known adverse effects of Anoplogaster cornuta on humans.
There are no known positive effects of Anoplogaster cornuta on humans.
Apart from hosting one known parasitic species, no significant ecosystem roles have been suggested or documented in Anoplogaster cornuta. In a small sample of A. cornuta collected near the Grand Banks, southeast of Newfoundland, it was discovered that Tautochondria dolichoura parasitizes them. No other parasites have been reported. Although the nature of its interaction with fangtooths was not studied, T. dolichoura was characterized by synampomorphies that indicated relation to a family of gill parasitizing copepods of Eudactylinidae, Lernanthropidae, and Pseudocyenidae.
Commensal/Parasitic Species:
Anoplogaster cornuta is carnivorous. Juveniles feed on crustaceans, while adults feed primarily on fish and shrimp. They have been observed to feed on fish one-third their size, necessitating the mechanism of reversed direction ventilation when feeding. Their large size allows them to swallow most prey whole. Due to their high mobility relative to other pelagic teleosts, it has been speculated that they are aggressive hunters. Other studies have suggested the contrary, describing them as voracious ambush predators.
Animal Foods: fish; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
Anoplogaster cornuta is found worldwide in tropical to temperate and subartctic seas, specifically within the range 65°N - 46°S, 180°W - 180°E. It is typically reported as a temperate to tropical species, though it has also been documented in the subarctic waters of the Pacific and Western Atlantic. It is native to at least 48 countries across the globe, and is found in regions such as Azores Exclusive Economic Zone, European waters, the Gulf of Mexico, Madagascar, Mozambique, New Zealand Exclusive Economic Zone, the north West Atlantic, South Africa, and the Spanish Exclusive Economic Zone. In Australia, A. cornuta has been observed from central to southern New South Wales.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Other Geographic Terms: holarctic
Anoplogaster cornuta is an exclusively marine species and exists from bathypelagic to mesopalagic depths ranging from 2 m to 4992 m below sea level; however, it is most common between 500 m and 2000 m. Adults are commonly captured at depths ranging from 75 to 5000 m, juveniles at 45 to 3100 m, and larvae at 2 m or more.
Range depth: 4992 to 2 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: pelagic
The average lifespan of fangtooths has not been documented.
Fangtooths have shortened, deep bodies with characteristically large mouth lined with sharp, fang-like teeth from which the species gained its common name. Relative to body size, they have the largest teeth of any marine species, with one of their most prominent features being a pair of long anterior fangs in the upper jaw. The length of their teeth prohibits them from completely closing their mouth. They are uniformly dark brown to black in color, and most of their body is covered with thin, prickly scales and spines. Lateral lines are seen as distinctly open grooves on either side of the body, and are partially covered with scales at various intervals. They typically have between 17 and 20 dorsal soft rays, seven to nine anal soft rays, and 28 vertebrae. They lack both dorsal and anal spines. Swim bladders are present, and relative to most other deep-sea fish, fangtooths have powerful muscles. Fangtooths are sexually dimorphic as adult females tend to be larger than their male counterparts.
Juvenile and adult fangtooths exhibit vast morphological differences. Juveniles have a long cephalic and preopercular spine. Their eyes are large, but their teeth are small and are not found on the palatine or the vomer. However, they have multiserial teeth on their premaxilaries. Juvenile gill rakers are described as long and slender. They have long head spines and are more lightly colored than adults. In contrast, adults do not have cephalic or preopercular spines. Their eyes are comparatively small, and their gill-rakers are tooth-like and are found in groups with bony bases. Juveniles begin to look like adults when they reach approximately 8 cm in length, and adults generally grow to a length of 17 cm.
Anoplogaster cornuta is stenothermic and is adapted to temperatures between 4°C and 6ºC. Due to the depths at which adults are typically found, various mechanisms have been proposed for its survival under high hydrostatic pressure in the oxygen minimum layers of the ocean. One study found that there was a significant positive relationship between oxygen consumption rates and critical oxygen tension, leading to at least two possible explanations. One is that A. cornuta only occasionally visits the oxygen minimum zone and that it is capable of sustained oxygen debt during these visits. Alternatively, these organisms might only engage in anaerobic metabolism in the oxygen minimum zone.
Range length: 18 (high) cm.
Average length: 17 cm.
Other Physical Features: homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Major predators of Anoplogaster cornuta include tuna (e.g., albacore), and marlin. Their dark brown to black color likely reduces predation risk at depths with little to no sunlight penetration.
Known Predators:
Anti-predator Adaptations: cryptic
As with all fish, Anoplogaster cornuta has large lateral lines along each side of its body. Lateral lines are essential in detecting changes in temperature and are important in detecting prey movements. Although they have eyes, their usefulness in perceiving the local environment has not been documented. Sunlight does not penetrate to bathypelagic depths at which adults may be found, and they are not bioluminescent. Thus, it is unlikely that their eyes are of much necessity at greater depths.
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Very little is known about reproduction in deep-sea fish, but many pelagic fish, including Anoplogaster cornuta, are believed to share similar reproductive mechanisms. They generally reach reproductive maturity at 13 cm in length. In many species, males are typically smaller than females, and tend to be parasitic of females, firmly latching onto their mate’s body with their jaws. Fertilization subsequently occurs, and its efficacy is dependent upon the female’s circulatory system. It is not known where the species reproduces, but it is believed that it has no special spawning areas.
Fangtooths spawn from June to August. Little else is known of reproduction in this species. Ceratioid anglerfishes ensure that both sexes are together at spawning time, which might also be occur in fangtooths.
Breeding season: Fangtooths are thought to breed from June to August.
Key Reproductive Features: sexual ; oviparous
Fangtooths are oviparous and have planktonic larvae. There is no parental care. Larvae, juveniles, and adults live in completely different regions of the ocean and little overlap occurs between habitats.
Parental Investment: no parental involvement
Anoplogaster cornuta, the common fangtooth, is a species of deep sea fish found in temperate and tropical oceans worldwide. It is found at depths of from 2 to 5,000 metres (10 to 16,400 ft) with the adults usually found from 500 to 5,000 metres (1,640 to 16,400 ft) and the young usually found near the surface. This species grows to a total length of about 18 cm (7 in). While a source of food for pelagic carnivorous fishes, this species is of no interest for human fisheries.
The common fangtooth has a distinctive appearance and grows to a total length of about 18 cm (7 in). Adults are dark brown to black, the head is very large, bony and finely sculptured but does not bear any spines. The eye is small and the gill rakers have bony bases and are tooth-like. The body is deepest just behind the head, tapering rapidly to the caudal peduncle. The mouth is well-armed with sharp fangs and the skin is granular. The dorsal fin has no spines and 17 to 20 soft rays while the anal fin has no spines and 7 to 9 soft rays. The lateral line takes the form of an open groove, bridged in places by overlapping scales. Many deep sea fish do not have swim bladders, but the common fangtooth does.[2][3]
Juveniles look very different from adults, so much so that they were at one time believed to be a different species.[2] The juveniles were first described as Anoplogaster cornuta by the French zoologist Achille Valenciennes in 1833, and it was fifty years later that the adults were described and given the name Caulolepis longidens. Not until 1955 was it appreciated that the two were the same species. The juveniles are a much paler colour and somewhat triangular in cross section. They have several long spines on the head, large eyes and slender, pointed gill rakers, but have small teeth and lack the fangs of the adult fish.[2][3] The skin is largely unpigmented and clad in unpigmented scales, but there is a black patch on the belly formed by dark-coloured cup-like scales. As the juvenile reaches adulthood, it becomes darker as black scales grow to cover its still-unpigmented skin.[4]
The common fangtooth has a global distribution being found in tropical and temperate waters in both the eastern and western Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Off the western seaboard of America its range extends from British Columbia southwards to south of the equator. It is a pelagic fish occurring between 2 and 5,000 metres (10 and 16,400 ft), with adults between 500 and 5,000 metres (1,640 and 16,400 ft); adults occur in deep water and are often caught in trawls at about 2,000 m (6,560 ft). Juveniles are found at lesser depths.[2]
The common fangtooth is a predator and feeds on other fish, crustaceans and cephalopods. They are themselves preyed on by such fish as tuna, marlin and albacore. It is a schooling fish and is often found in small groups, though it may be solitary. Off the west coast of North America, the common fangtooth seems to breed in the summer months. The fish are oviparous and the developing larvae are planktonic.[3] From examination of the otoliths (bony structures behind the eyes), it appears that this fish lives for at least three years.[2]
These fish were tested to see how pressure affects their respiration as compared to other fish. Researchers found that these fish are able to regulate their respiratory system according to their environment and that the respiration rate was directly proportional to the size of the fish.[5]
Although almost no light penetrates to the deep sea from the surface, the common fangtooth has evolved features that make it practically invisible. Like other deep sea fish, it needs to avoid being seen by predators, some of which hunt for prey by creating their own light by means of bioluminescence. The common fangtooth achieves invisibility by absorbing light with great efficiency. The pigment melanin is crammed into granules which are grouped into melanophores which cover virtually the whole of the dermis. This absorbs almost all of the incoming light, and any remaining light that scatters sideways is absorbed by neighbouring granules. Altogether, the absorption of light is 99.5% efficient, a fact that makes photographing this fish in its natural habitat very difficult.[6]
Anoplogaster cornuta, the common fangtooth, is a species of deep sea fish found in temperate and tropical oceans worldwide. It is found at depths of from 2 to 5,000 metres (10 to 16,400 ft) with the adults usually found from 500 to 5,000 metres (1,640 to 16,400 ft) and the young usually found near the surface. This species grows to a total length of about 18 cm (7 in). While a source of food for pelagic carnivorous fishes, this species is of no interest for human fisheries.
