Five rare, deep-water sharks have been caught off the coast in Taitung in Taiwan, boasting ink-black skin, protruding jaws and more sharp ends than a pack of nails.
The viper dogfish, Trigonognathus kabeyai, is a mysterious species that lives in the Pacific Ocean around Japan, Taiwan and Hawaii. Little is known about the animals, which were only discovered in 1986.
As Science Alert reports, viper dogfish have only been seen a handful of times in the past decade, normally caught by accident. Their deep-water habitat and supposedly small population mean they are incredibly elusive, so while scientists know something of their taxonomy, there’s still a great deal about the beasties that is uncertain.
Aside from more than a passing resemblance to a certain Spiderman villain, the viper dogfish has a number of interesting features. For starters, it has a concentration of light-emitting glands on its underside, which could have evolved for a couple of reasons. The bioluminescence may attract prey or potential mates, although the fact they only exist on its ventral surface suggests it may be used to hide from predators.
Camouflage with light might sound counterintuitive, but for predators swimming below the viper dogfish, the faint glow of the shark’s underside would mask the animal’s movement against the distant light of the surface.
(Above: An image from a 2016 catch Japan. Credit: Fisheries Research Institute)
The shark also has an extendable jaw, allowing its fang-like teeth to quickly reach out and snatch prey. From what has previously been found in the bellies of viper dogfish, it seems like the shark feeds on bony fish and crustaceans, swallowed whole.
The viper dogfish measures around 54cm (21 inches) in length, and is believed to swim around 270 – 360m. The five sharks were caught by the Taiwanese Fisheries Research Institute as part of a survey of species living around Taitung, with local reports claiming all but one were dead when caught. The surviving fish lasted one day with the researchers before it too perished.
Like these five sharks, viper dogfish tend to be dredged accidentally through deep-sea trawls, rather than by targeted fishing. Little is known about how many viper dogfish are in the wild, and whether fishing has any effect on its population, leading the International Union for Conservation of Nature and Natural Resources (IUCN) to claim it currently has insufficient data on the shark to assess its conservation status.
Lead image credit: Fisheries Research Institute