Scientists know about 400 species of sharks: some of them are common, others are described only by single individuals. The viper shark is rare, but recently representatives of this species have been caught in the nets off the coast of Taiwan.
Taiwanese fishermen, while dismantling the nets, discovered amazing fish - blue-black, blue-eyed, and their small heads were decorated with sharp teeth.
All of them were already dead - with the exception of one, and she died before she fell into the hands of scientists. Nevertheless, biologists were pleased with the find: they identified it as a shark of a rare species Trigonognathus kabeyai. In English, this fish is called viper shark: viper shark. It has no poisonous glands - the name was given for its resemblance to a snake. And the common name of the genus Trigonognathus is due to the characteristic shape of the jaws (ancient Greek τρίγωνον "triangle" and γνάθος - "jaw").
The viper shark belongs to the etmopter family of the katraniform order. All 45 species of etmopterids have several common features: their length does not exceed 90 cm, they all live at great depths and have photophores. This luminous organ is a mucus-filled gland that contains bioluminescent bacteria. The ability to glow is needed by deep-sea predators: shimmering bodies lure prey in the dark.
Trigonognathus kabeyai lives at depths of 270 to 360 meters, so it hardly catches the eye of humans. The first specimens, two immature males, were caught in 1986 off the southern coast of Japan by a bottom trawler. Over the next decades, these fish were rarely caught in the nets - and several times they were found in the stomachs of larger predators (for example, tuna). In all cases, the fishermen caught Trigonognathus kabeyai in the evening. This allows us to conclude that at this time the fish rise to the surface of the water.
Little is known about the life of viper sharks. On average, their size is about 50 cm, and the jaws are able to move forward. Their long, thin teeth are adapted to grab, not cut, and this makes the shark different from other katranoids, which cut through the flesh of the victim during a bite. The viper shark is able to swallow whole fish up to 40% of its own size.
Promotional video:
Anastasia Barinova