These sea snakes can sense light using their tails

A new study led by the University of Adelaide has found that some species of Australian sea snakes have a remarkable way of protecting their tails from predators. The snakes have adapted the ability to sense light on their tail skin, which prompts them to seek shelter.

“Sea snakes live their entire lives at sea, swimming with paddle-shaped tails and resting at times during the day under coral or rocky overhangs,” said study lead author Jenna Crowe-Riddell. “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.”

Out of eight species of sea snakes that were analyzed, only three species were found to have the light-sense ability.

“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. There are more than 60 species of sea snake so that’s less than 10% of all sea snakes,” said Crowe-Riddell. “We don’t know why this rare sense has evolved in just a few Aipysurus species.”

By using RNA sequencing, the researchers were able to determine which genes were active in the skin of the sea snakes. They found a gene for a light-sensitive protein called melanopsin, as well as several genes that are involved in signaling the nervous system in the presence of light.

“Melanopsin is used in a range of genetic pathways that are linked to sensing overall light levels around us. It is even used by some animals, including humans, for regulating sleep cycles and in frogs to change their skin colour as a camouflage,” explained Crowe-Riddell.

Dr. Kate Sanders added, “We’ve confirmed the ability of olive sea snakes to sense light in their tails and found the same ability in two other species. We’ve identified a shortlist of genes that are likely to be involved in detecting light. But further study will be needed to target these genes before we can really understand the genetic pathways involved in this fascinating behavior.”

The study is published in the journal Molecular Ecology.

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By Chrissy Sexton, Earth.com Staff Writer

Image Credit: Chris Malam