Day 380#: Common Fangtooth
Today's animal of the day is the Common Fangtooth (Anoplogaster cornuta)!
Photo credit: MBARI
Also known as the ogrefish, this species of deep-sea fish can be found in temperate and tropical oceans around the world, usually at depths between 1,640 ft and 16,400 ft. While they might look slightly terrifying with their long, sharp fangs and inky-black coloration, these guys are actually pretty tiny and only grow to around 7 inches long. As you might have guessed by their namesake fangs, these fish are predators and will feed on a variety of smaller fish as well as crustaceans and cephalopods. However, they themselves are also commonly preyed upon by many other species of open ocean predators, such as albacores, marlins, and tunas.
Photo credit: peterraskmoller on iNaturalist
Usually, it's the juveniles who end up getting eaten by larger fish, as they tend to live closer to the surface and look wildly different compared to the adults. In fact, they look so different that for many years the juveniles and adults were thought to be totally separate species! The paler juveniles (which also lack fangs and have more triangular bodies) were first described as Anoplogaster cornuta by French zoologist Achille Valenciennes in 1833, and it wouldn't be until 50 years later that the deep-sea adults would be discovered and named Caulolepis longidens. The truth about these two "species" wouldn't be revealed until 1955, and since the name Anoplogaster cornuta was described first, that's the name that stuck, while Caulolepis longidens became a nomen dubium.
Photo credit: Gonzalo Mucientes Sandoval
Adult common fangtooths (common fangteeth?) have several adaptations to help them survive in the deep, dark depths. First of all, they seem to be able to regulate their respiratory system depending on their environment and the size of the individual fish, which helps them survive the crushing pressure of the deep-sea. While they have very poor eyesight, their prominent lateral line helps them to detect the movement of prey in the pitch black water. Their scales are also chock full of melanin, which gives them their dark coloration. Because of this abundance of melanin, their bodies absorb any light they encounter. Usually, the deep sea is a pretty dark place, except for the bioluminescent glow of various deep-sea predators, which use their lights to locate and lure in prey. Luckily, by absorbing any nearby light, the common fangtooth becomes basically invisible! This also makes it extremely hard to photograph the common fangtooth in its natural habitat, so most photos available of these guys are of dead individuals that were caught as bycatch by deep-sea trawlers. Though pics and videos of live specimens do exist, such as this video taken by the Monterey Bay Aquarium Research.
