COUNCIL CHRONICLE – Scientists have reported their having found a new shark species in the Atlantic Ocean. According to the paper published in the science journal Marine Biodiversity, genetic tests confirm that the Atlantic sixgill shark is a different and separate species from sixgill sharks in the Pacific and Indian Oceans.
Scientists’ DNA Tests Confirm New Shark Species
Sixgill sharks are large, deep-sea sharks that are only rarely encountered. Their earliest known ancestors lived sometime around 250 million years ago and thus predated the dinosaurs. Sixgill sharks belong to their own order, family, and genus.
Until recently, authorities believed there were only two such species, the bigeye sixgill (Hexanchus nakamurai) and the bluntnose sixgill (H. griseus). These sharks have been found in the Pacific, Indian, and Atlantic Oceans.
Still, some researchers have been wondering if some of the apparent bigeye sixgills in the Atlantic weren’t actually a separate species.
To find out, lead researcher Toby Daly-Engel of Florida Institute of Technology and his colleagues collected DNA samples. These were taken from sharks in all the three oceans. The scientists analyzed 1310 base pairs from two genes in the mitochondria.
In doing so, they found enough differences to prove the existence of a third, different species. They named this the Atlantic sixgill (H. vitulus).
Researchers had previously suspected the existence of a third sixgill species in the Atlantic Ocean. While the sharks in the Indian and Pacific Oceans could grow to be 15 feet long, the Atlantic sixgill sharks are only six feet long.
They also have unusual, saw-like teeth in their lower jaw. Aside from these differences, Atlantic sixgills strongly resemble their bigger cousins.
Dr. Daly-Engel noted that identifying a new species will help shark conservation efforts. Researchers now know that shark populations in one ocean will not be able to replace an overfished population in another one.
While sixgill sharks have had little contact with humans so far, that could all change as people continue fishing in deeper waters.
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