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Seen the sawsharks? Sharp scientists discover two new shark species

The three known species of sawshark are shown. the new Pliotrema kajae is shown on the left, while the new Pliotrema annae is on the right.
The three known species of sawshark are shown. the new Pliotrema kajae is shown on the left, while the new Pliotrema annae is on the right. Simon Weigmann/The Conversation

Scientists say they’ve discovered two new shark species that are a cut above the rest, with long, serrated “saw” noses and extra gills.

Both new species of six-gill sawsharks were recently discovered around their habitats in the West Indian Ocean, according to findings published by an international team of scientists in the journal PLOS-ONE.

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One species, dubbed Pliotrema annae, was hauled out of the ocean by a fisherman in Zanzibar.

A six-gill sawshark (Pliotrema annae) is shown in this handout photo.
A six-gill sawshark (Pliotrema annae) is shown in this handout photo. Ellen Barrowclift-Mahon/Marine MEGAfauna Lab/Newcastle University via The Conversation

The other species, called Pliotrema kajae, was discovered based on several collected noses in Madagascar, including existing specimens in museum collections.

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Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo.
Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo. Weigmann S, Gon O, Leeney RH, Barrowclift E, Berggren P, Jiddawi N, et al.

“The discovery reinforces both how important the western Indian Ocean is in terms of shark and ray biodiversity, but also how much we still don’t know,” researcher and study co-author Andrew Temple said in a news release through Newcastle University in the U.K.

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Both species have long, saw-shaped snouts with hooked barbs along the thin edges that help them sense their environment and catch prey.

All that makes them look pretty weird, especially when you notice that the underside view resembles a grumpy-looking face.

Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo.
Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo. Weigmann S, Gon O, Leeney RH, Barrowclift E, Berggren P, Jiddawi N, et al.

The sharks can grow up to 1.5 metres (5 feet) long and typically eat squid, fish and crustaceans, Temple said.

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Sawsharks look similar to sawfish but the two are actually quite different, according to Simon Weigmann, another author on the study who works at the Elasmobranch Research Laboratory in Hamburg, Germany.

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Sawfish actually belong to the ray family, Weigmann explains in an article for The Conversation. Sawsharks are also much smaller than sawfish, which can grow up to 7 metres long.

“Sawsharks have gills on the side of their heads, whereas sawfish have them on the underside of their bodies,” he wrote. He also pointed out that sawfish don’t have the same barbels, or whiskers, that sawsharks have on their noses.

Scientists have not seen either species in the wild.

Scientists discover new species of walking sharks
Scientists discover new species of walking sharks

The discoveries highlight the need for fisheries to report any sharks they find during their operations, Temple says. Better reporting practices will help researchers monitor and protect more vulnerable species, he says.

Weigmann adds that it’s critical to get a look at the sharks that small fisheries catch, because many species could go extinct before they’re even discovered.

Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo.
Pliotrema kajae, a species of six-gilled sawshark, is shown in this handout photo. Weigmann S, Gon O, Leeney RH, Barrowclift E, Berggren P, Jiddawi N, et al.

Only one species of six-gilled sawshark was known to exist before this latest discovery, Weigmann said.

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“The six-gill sawsharks are really quite extraordinary, as most sawsharks have five-gill slits per side,” he told CNN.

Tourists stunned by shark swimming on its back: ‘Is that normal?’
Tourists stunned by shark swimming on its back: ‘Is that normal?’

Temple told CNN that the sharks are a fantastic example of peak evolution.

“They are so perfectly adapted to their environment and the world around them that they have existed, virtually unchanged, for millions of years,” Temple said.

“They were around before trees.”