Fangtooth

The fangtooth is a small but formidable-looking deep-sea fish found in tropical and temperate oceans worldwide, notable for possessing the largest teeth relative to body size of any fish species. Despite its fearsome appearance, Anoplogaster cornuta is typically no more than about 16 cm long as an adult. Fangtooth inhabit the mesopelagic and bathypelagic zones and have evolved unusual sockets on either side of the brain to accommodate their oversized lower fangs when the mouth is closed. The species is found across a very broad depth and geographic range, reflecting a generalist deep-sea lifestyle, and it is frequently used as an example of extreme adaptation to life in permanently dark, food-scarce deep ocean environments.

Fangtooth are compact, heavy-bodied deep-sea fish easily identified by their oversized dentition.

• Extremely large fang-like teeth in the lower jaw, so long that closed-mouth sockets exist beside the brain to accommodate them
• Large, disproportionate head relative to a short, deep body
• Dark brown to black coloration
• Rough, spiny scales and a bony, armored-looking head
• Small eyes, relatively reduced compared to other deep-sea predators

Fangtooth are distinguished from viperfish and dragonfish, which have elongated, slender bodies, by their notably short, deep, compact body shape combined with their disproportionately massive fangs and armored head.

Fangtooth are found in tropical and temperate oceans worldwide, occupying an unusually broad depth range from around 200 meters to over 5,000 meters, spanning the mesopelagic through bathypelagic zones. Juveniles tend to occupy shallower depths than adults, which are more commonly found in deeper, colder water. Fangtooth live entirely within the open water column in the permanent darkness below the reach of sunlight, showing no association with the seafloor. Their broad geographic and depth distribution suggests a generalist tolerance for the extreme pressure, cold, and food scarcity that characterize the deep ocean environment across much of the world's ocean basins.

Fangtooth are solitary ambush predators that rely on their oversized fangs to seize and hold onto prey encountered in the food-scarce deep sea, striking at fish and crustaceans that come within range rather than actively pursuing prey over distance. Unlike many mesopelagic species, fangtooth do not appear to undertake pronounced daily vertical migrations, instead remaining largely within deeper water throughout the day. Because encounters with prey are rare in the deep sea, fangtooth are opportunistic feeders capable of consuming prey close to their own body size. Little is known about their reproduction, though like most deep-sea fish they are believed to release pelagic eggs that develop in the open water column.