Bio

A new type of ghost shark has surfaced: Hydrolagus erithacus. It was discovered by Kristin Walovich of the Pacific Shark Research Center at the Moss Landing Marine Laboratories in California and several of her colleagues. Described from nine specimens found in the southeastern Atlantic and southwestern Indian Oceans at depths of 470 to 1,000 meters, this discovery was almost entirely accidental.

Two unlucky members of this species were caught as bycatch by a deep-sea longline fishing vessel. The vessel was fishing near Prince Edward Island, halfway between South Africa and Antarctica. “Scientists from the South African Department of Agriculture, Forestry and Fisheries (DAFF) obtained the specimens, and I was able to observe them in South Africa,” explains Kristin Walovich. With one of her colleagues, she then studied other specimens from the fish collection of the Izikio South African Museum. “Some of them had been there for 20 years, but no one had taken the time to look at them,” the researcher continued.

Unique and strange ghost shark

Species of the genus Hydrolagus, which are very similar, prove difficult to distinguish morphologically. “However, in this case, its color, its large head relative to its body, and its large size at maturity distinguish Hydrolagus erithacus from the others.” “We also used genetic analysis to distinguish it,” adds Kristin Walovich. This rather unusual animal differs from its relatives in several ways. Indeed, comparing the sequences of the mitochondrial NADH2 gene with other Hydrolagus species suggests that this ghost shark is a distinct species. It also stands out due to its large size: 1 meter in length, which places it second among the fifty known ghost shark species. Finally, it is distinguished by the uniform black coloration of its skin.

Regarding its other physiological features: canals equipped with numerous pores on the front of its head allow it to detect its prey in desperately dark environments. A venomous spine precedes its first dorsal fin. The second extends over no less than 80% of the animal’s length. It also uses its pectoral fin for propulsion, in a flapping motion. Unlike other sharks that use their fins… tails.

Moreover, this chimaera sports impressive teeth… like a rabbit’s. This is precisely why this species belongs to the genus Hydrolagus, literally “water hare” in Greek. Like its relatives, its skeleton is composed exclusively of cartilage, with the exception of its teeth and the thin spine, which are calcified. Paradoxically, these strange, usually elusive creatures of the deep sea regularly manage to make headlines, whether it’s the discovery of a new species or the filming of others, no less curious. For example, last December, a camera accidentally captured, for the first time, images of a blue chimaera with a pointed nose, off the coast of Hawaii and California, at a depth of 1,641 meters.

Source : Science & Avenir