Anoplogaster cornuta

Geographic Range

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 nearctic
  • native native
• palearctic palearctic
  • native native
• oriental oriental
  • native native
• ethiopian ethiopian
  • native native
• neotropical neotropical
  • native native
• australian australian
  • native native
• oceanic islands oceanic islands
  • native native
• indian ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• holarctic holarctic

Habitat

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.

• Habitat Regions
• temperate temperate
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic

Physical Description

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.

• Other Physical Features
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Development

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.

Reproduction

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.

• Key Reproductive Features
• sexual sexual
• oviparous 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

Lifespan/Longevity

The average lifespan of fangtooths has not been documented.

Behavior

Anoplogaster cornuta is highly mobile and is an aggressive hunter relative to other deep-sea species. They can either be found swimming alone or in schools. Many teleost fish share the same general mechanism of gill ventilation, with a buccal force pump and an opercular suction pump working together to maintain a consistent flow of water through the mouth and over the gills. However, when A. cornuta consumes large prey, it employs a different mechanism whereby its opercula are greatly distended, which visibly exposes all of the gill arches and allows one to see into the posterior buccal cavity. This species maintains opercular distension while handling its prey, ceasing only after prey has been swallowed. When fangtooth’s have a full mouth, they are prohibited from efficiently pumping water over the gills for respiration. Opercular distension produces large gaps between its gill arches, and it subsequently uses its pectoral fins to fan seawater over the gills from behind. Reverse direction ventilation is unique to A. cornuta and lampreys .

• Key Behaviors
• natatorial natatorial
• motile motile
• solitary solitary
• social social

Home Range

There is no information available regarding the average home range size of Anoplogaster cornuta .

Communication and Perception

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 visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• aquatic crustaceans

Predation

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.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

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 .

Economic Importance for Humans: Positive

There are no known positive effects of Anoplogaster cornuta on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Anoplogaster cornuta on humans.

Conservation Status

The population trends of Anoplogaster cornuta have not been documented. Thus, the potential conservation and management needs of this species are unknown.

Additional Links

Encyclopedia of Life

Contributors

Rishi Malhotra (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, John Berini (editor), Animal Diversity Web Staff.

References

Bailly, N. 2010. "Anoplogaster cornuta (Valenciennes, 1833)" (On-line). World Register of Marine Species. Accessed February 24, 2011 at http://www.marinespecies.org/aphia.php?p=taxdetails&id=126393 .

Bond, C. 1979. Biology of Fishes . Philadelphia, PA: W.B. Saunders Company.

Chakrabarty, P. 2009. "Fangtooth" (On-line). Digital Fish Library. Accessed March 21, 2011 at http://www.digitalfishlibrary.org/featured/fangtooth/ .

Davenport, J. 2005. Ventilation of the Gills by the Pectoral Fins in the Fangtooth Anoplogaster cornutum: How to Breathe With a Full Mouth. Journal of Fish Biology , 42: 967-970.

Fothergill, A. 2001. "Fangtooth in the Abyss - Blue Planet - BBC Wildlife" (On-line video). YouTube. Accessed February 24, 2011 at http://www.youtube.com/watch?v=_lOwi6upg4I .

Fujita, K. 1976. Stomach Content Analysis of Longnose Lancetfish, Alepisaurus ferox in the Eastern Indian Ocean and the Coral Sea. Jap. J. Ichthyol , 23: 133.

Gordon, M. 1976. Comparative Studies on the Metabolism of Shallow-water and Deep-sea Marine Fishes. IV. Patterns of Aerobic Metabolism in the Mesopelagic Deep-sea Fangtooth Fish Anoplogaster cornuta. Marine Biology , 3: 287.

Ho, J. 1987. Tautochondria dolichoura n. g., n. sp., a Copepod Parasitic on the Bathypelagic Fish Anoplogaster cornuta (Valenciennes) in the Western North Atlantic. Systematic Parasitology , 9: 179.

Kotlyar, A. 1986. Classificiation and Distribution of Fishes of the Family Anoplogasteridae (Beryciformes). Journal of Ichthyology , 26: 133-152.

McGrouther, M. 2010. "Fangtooth, Anoplogaster cornuta (Valenciennes, 1833)" (On-line). Australian Museum. Accessed February 23, 2011 at http://australianmuseum.net.au/Fangtooth-Anoplogaster-cornuta-Valenciennes-1833 .

Meek, R., J. Childress. 1973. Respiration and the Effect of Pressure in the Mesopelagic Fish Anoplogaster cornuta (Beryciformes). Deep Sea Research and Oceanographic Abstracts , 20: 1111-1112.

Post, A. 1986. "Anoplogaster cornuta, Common fangtooth" (On-line). FishBase. Accessed February 23, 2011 at http://www.fishbase.org/Summary/SpeciesSummary.php?ID=2308&AT=fangtooth .

Shimizu, T. 1978. Record of the Beryciform Fish, Anoplogaster cornuta, From the Western North Pacific. Jap. J. Ichthyol , 25: 65-67.

"Anoplogaster cornuta" (On-line). Marine Species Identification Portal. Accessed March 22, 2011 at http://species-identification.org/species.php?species_group=fnam&id=1157 .

2005. "Fact Files: Anoplogaster/Fangtooth" (On-line). BBC. Accessed February 24, 2011 at http://www.bbc.co.uk/nature/blueplanet/factfiles/fish/fangtooth_bg.shtml .