It is easy to see where the common fangtooth gets its name. These fish have mouths that are absolutely full of long, pointed teeth, perfect for catching and hanging on to prey of just about any size that wanders by in the deep sea. Common fangtooths are deep-sea predators that have been recorded at depths of well over 16,000 feet (nearly 5000 m).
Though they spend most of their time in the deep, common fangtooths are known to migrate toward the surface, at night, following their preferred prey of crustaceans and other fishes. Common fangtooths are more active than many other deep-sea fishes and seek out food, rather than being purely ambush (sit and wait) predators. Their huge mouths and very long teeth ensure that they are able to attack prey that they find in the very large, food-poor deep sea.
Common fangtooths are dark colored – either solid brown or black – and unlike most deep-sea fishes, they do not have light producing organs or cells for communication or to attract prey. Instead, they rely heavily on their sense of smell and benefit from even the slightest bit of sunlight that may make it down to the depths. Though the light is not enough to truly see, it may be enough that potential prey species cast a shadow as they pass overhead. In those circumstances, this species seems to have a bit of a “bite first, ask questions later” attitude.
As they live in an extreme environment where scientists have difficulty studying behavior, little is known about the mating preferences of this species. They are known, however, to reproduce via external fertilization, where females release their eggs and males release their sperm into the open water at the same time.
The common fangtooth, along with the only one other species of fangtooth, is more closely related to shallow-water squirrelfishes than to other deep-sea fishes. Though they look menacing and are voracious predators, common fangtooths are harmless to humans. They live in the deep sea and only grow to about 7 inches (18 cm) long.