Fangtooth

The fangtooth looks like something from a horror movie, with fangs so large they barely fit inside its mouth. This deep-sea predator, thriving in one of the harshest environments on Earth (the midnight zone of the ocean), is only about the length of a dollar bill. The fangtooth is a small, tough, and fascinating survivor of the deep.

4 Incredible Fangtooth Facts

• Juveniles look so different from adults that scientists once thought they were an entirely separate species.
• They have the largest teeth proportionate to their body size of any fish in the ocean.
• They have extremely compressed bodies with huge heads, enormous jaws, and a gruesome, corpse-like appearance.
• Fangtooth fish live in the deep sea in the bathyal zone, also known as “the midnight zone.”

Classification and Scientific Name

The fangtooth fish is part of the genus Anoplogaster. This name comes from the Greek words anoplo, translating to “unarmed”, and gaster, meaning “stomach.” It is a member of the family Anoplogastridae.

The two recognized species are the shorthorn fangtooth (Anoplogaster brachycera) and the common fangtooth (Anoplogaster cornuta).

The common fangtooth is the larger of the two and grows to 6.3 in in length at most, while the shorthorn fangtooth is believed to be less than half this size, based on measurements of young fish.

Shorthorn fangtooths are found in tropical and subtropical regions of the Atlantic and Pacific Oceans, while common fangtooths are present in tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans.

Evolution and Origins

There is limited data on the fangtooth due to its deep-ocean habitat, and scientists have not identified any close relatives of this species. While the dragonfish might belong to the same class of Actinopterygii bony fish as the fangtooth, shares the same habitats, and is similar in its large head and long, sharp teeth, it is not related and belongs to the Stomiidae family.

In 2020, scientists found that the fangtooth can be considered an ultra-black fish as its body absorbs 99.5% of the light that touches it. The skin is covered with tightly packed melanosomes that absorb light through pigment particles. Studying 15 other species of ultra-black fish, they believe that each species evolved the ability to absorb light independently and does not have any common ancestors. They believe the ultra-black could provide camouflage from any predators as well as keep them hidden in the depths of the sea, so they can more efficiently catch prey.

Appearance and Adaptations

Fangtooth fish, like many other deep-sea creatures, are dark in color and somewhat grotesque in appearance. Similar to anglerfish, the fangtooth fish has an enormous jaw with huge, vicious-looking teeth. In fact, the fangtooth fish has the largest teeth proportionate to its body size of any known fish. The fangs of their lower jaws are so big that they had to evolve special sockets on either side of their head to accommodate them.

Because it lives so deep in the ocean, its body is extremely laterally compressed, which means it appears quite thin when viewed from above. Its disproportionately large jaw and thin skin give it a cadaverous look, especially when combined with its sharp, spiny scales and small, ragged fins. As far as researchers know, both males and females have similar appearances, but males tend to be smaller than females. This is true of many deep-sea fish species.

Fangtooths have small, cloudy eyes, and they are believed to have extremely poor eyesight. To compensate for this, they have exceptionally well-developed lateral lines that can be easily seen on either side of their bodies. A lateral line is a special sensory organ system that fish have to help them detect movement and pressure changes in the water around them.

Despite their vicious appearance, fangtooth fish are quite small and essentially harmless to humans. When they are fully grown, they typically only reach about 6 inches in length. For reference, this is about the same length as a dollar bill. Scientists do not know what the average weight of a fangtooth fish is.

Behavior and Ecology

These are hardy and adaptable fish. It is believed that they practice diurnal vertical migration — rising closer to the surface at night to hunt and returning to the depths during the day.

They can also survive dramatic changes in water pressure and temperature. Some have even lived for months in aquariums despite being far outside their natural habitat.

Distribution and Habitat

The fangtooth fish can be found across the world. It lives in what is known as the “bathyal zone” of the ocean, which means that it is classified as a “bathypelagic” fish. The bathyal zone is the region of the deep sea that stretches from about 3,300 to 13,100 feet (1,000 to 4,000 meters) below the surface and is also home to other fish species such as anglerfish, dragonfish, gulper eel, and amphipods.

Because no sunlight touches those waters, the bathyal zone is also known as the “midnight zone.” The temperature typically stays around 40 degrees Fahrenheit. Between the lack of sunlight and freezing temperatures, there is no plant life in this part of the ocean.

Diet: What Do Fangtooths Eat?

Fangtooth fish are part of a larger order of fish known as Beryciformes. Most Beryciformes are carnivorous, which means that they are fish with teeth that feed on other animals, like crustaceans. Unfortunately, because they are also nocturnal, deep-sea dwellers, scientists do not know much about them because they are difficult to study.

They do know that adult fangtooths feed on small fish, but they are also known to prey on larger squid as well. Their enormous teeth help them more easily hunt their meals. Juvenile fangtooths eat by filtering zooplankton from the water.

Predators and Threats

Despite their small size, fangtooths do not have many predators. They are primarily hunted by much larger tuna and marlins, but those are their only main threats.

Reproduction and Lifespan

Little is known about the lifespan and reproduction habits of fangtooth fish simply because they live so far down in the depths of the ocean. However, scientists do know that they are oviparous, which means that the females lay a large clutch of eggs, and the males then fertilize them.

They do not appear to guard their eggs; instead, the larvae are left to fend for themselves when they hatch. This is a common trait for deep-sea fish. In fact, larvae, juveniles, and adults all live in different depths of the ocean, so they tend to exist completely separately.

Juvenile fangtooths look so different from their adult counterparts that scientists originally classified them as a completely different species of fish. They are gray instead of black and have much larger eyes and a functional gas bladder, which helps to control buoyancy. Juveniles also have long gill rakers, slender spines on their heads, and much smaller teeth, so it’s no surprise that they were thought to be a different species at first.

It is not known how long fangtooth fish can live. Researchers have noted that fangtooth fish are incredibly tough and adaptable, however. A few specimens that have been caught and kept in aquariums have survived many months despite the wildly different water pressure and overall habitat.

Role in the Ecosystem

Fangtooths play a key role as mid-level predators in the deep sea. By feeding on smaller fish and squid, they help regulate populations and provide food for larger species like tuna and marlin.

Conservation Status

As with many fish found in the deep sea, scientists are not exactly sure how many fangtooth fish exist in the wild. However, they are listed as a species of Least Concern by the IUCN, so they are not in danger of extinction. Climate change and ocean acidification may impact their ecosystems in the future.

Fangtooth vs. Other Deep-Sea Fish

Fangtooth and Humans

Eating fish with teeth might sound appealing to some of the more adventurous seafood lovers of the world, but in general, fangtooth fish are of little interest to fishermen.

Fishermen may occasionally catch these fish in their nets, but they do not actively seek to catch them commercially or recreationally.

Population

Although the exact number of fangtooths is unknown, fangtooths are believed to be relatively widespread. Their “Least Concern” status reflects a stable population, though much remains to be studied.