Trigonognathus kabeyai, commonly known as the Viper dogfish, is a rare species of deep-sea shark found in the Pacific Ocean. It is characterized by its long, slender body, needle-sharp teeth, and bioluminescent organs. This nocturnal predator is known for its unique jaw structure and ability to unhinge its jaw to catch prey.

Trigonognathus kabeyai, commonly known as the viper dogfish, is native to the Northwest Pacific Ocean. It has been found in the waters off Japan, including the Suruga Bay and the Pacific coast of Honshu, as well as off Taiwan and the Philippines.

The viper dogfish inhabits deep-sea environments, typically at depths ranging from 270 to 360 meters. This species is known to prefer the continental slope and upper continental rise, where the water is cold and the pressure is high.

As a deep-sea predator, Trigonognathus kabeyai occupies a niche where it preys on small fish and cephalopods. Its unique jaw structure suggests it is adapted to capture fast-moving prey in the dark, low-visibility conditions of the deep ocean. The species is believed to be a nocturnal hunter, ascending in the water column at night to feed.