New species of sea snake discovered

A new species of turtle-headed sea snake has been discovered in Western Australia, bringing the total number of species native to the WA coasts to six.

Emydocephalus orarius, otherwise known as the Western Turtle-headed sea snake was found in soft, sandy habitats in Western Australia’s Coral Coast, Pilbara, and Kimberley Regions.

The researchers from the University of Adelaide say this particular sea snake is different from other species of turtle-headed sea snakes which often live in shallow coral reefs, rather than sandy habitats.

The team reports in the journal Zootaxa a number of the new species were found on the research trawls from Shark Bay to Broome, as well as seven specimens found in museums.

Turtle-headed sea snakes are an unusual group of snakes that feed exclusively on fish eggs and have a highly degenerated venom system which renders them harmless to humans.

Subtle differences from other species

“We had suspected for some time that there may be undiscovered species of turtle-headed sea snake because they are morphologically variable with a wide geographic distribution,” says James Nankivell, who led the research.

“When we compared genetic data between the new species and the others we were surprised at how distantly related it was to the other two species.”

The researchers highlight that the new species tend to be larger than other species. They also suggest subtle differences between species in scalation.

“Snakes from the Pilbara are usually heavily spotted while those from Shark Bay have highly contrasting bands”.

Western Australia a hot-spot for sea snake diversity

 The discovery brings the total number of sea snakes endemic to Western Australia to six.

“Western Australia is a hot spot for sea snake diversity in Australia but was poorly surveyed until recently,” Nankivell says.

“This has also resulted in the rediscovery of a couple of species previously thought extinct.”

The Leaf-scaled sea snake and Short-nosed sea snake disappeared from Ashmore Reef but were later found to be relatively common along the coastline of Western Australia.

It appears as though the Western Turtle-headed sea snake isn’t under serious threat, but Nankivell suggests that it is still vital to conservation that new species are described.

“We can’t assess or protect an organism if we don’t know that it exists.”

Recent slithery finds

The discovery comes after a year of revelations about Western Australian sea snakes.

In February 2019 the University of Adelaide team found olive sea snakes can sense light on their tail skin. When light shone on their tail, they moved their tail away from the source and into shelter. This prompted the researchers to suggest this is an adaptation to keep the tail hidden from sharks and other predators.

“Because sea snakes have long bodies, the tail-paddle is a large distance from the head, so benefits from having a light-sense ability of its own,” University of Adelaide researcher Jenna Crowe-Riddell said at the time.

“The olive sea snake was the only reptile, out of more than 10,000 reptile species, that was known to respond to light on the skin in this way.”

The researchers believe only 6 species of sea snake, out of 60 worldwide, are likely to have this capability.

Deep diving sea snake
The deepest diving sea snake, spotted 245m below the surface. Credit: INPEX Icythys LNG Project

Then, in April 2019 a sea snake was spotted deep-diving an incredible 245 metres below the surface. At that depth it was almost twice as deep as the previously deepest-diving snake seen.

The snake was spotted by an underwater drone operated by an oil and gas exploration company off the Kimberley region.

“We have known for a long time that sea snakes can cope with diving sickness known as ‘the bends’ using gas exchange through their skin,” Crowe-Riddell said at the time. “But I never suspected that this ability allows sea snakes to dive to deep-sea habitats.”

Sea snakes were also spotted near Esperance, on Western Australia’s south coast for the first time in August 2019. The find came as a surprise given the cold local waters.

“As the climate warms we will see sea snakes spread further south,” James Cook University sea snake expert Blanche D’Anastasi told the ABC.

“There is some early evidence that sea snakes are occurring in cold, temperate waters with increasing frequency.”

Finally, in September, a sea snake found in Australia, Asia and the Middle East was found to breathe through the top of its head. A complex network of blood vessels just below the surface of its snout and forehead are thought to operate similar to a fish’s gills.

They are elusive, mysterious, and terrifying creatures.

This article was first published on Australia’s Science Channel, the original news platform of The Royal Institution of Australia.

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