Sea snakes can sense objects at a distance by feeling movements in the water

June 8, 2016 by Robyn Mills

The move from life on land to life in the sea has led to the evolution of a new sense for sea snakes, a University of Adelaide-led study suggests.

The international team, led by researchers in the University's School of Biological Sciences, studied tiny and poorly understood structures on the heads of snakes called 'scale sensilla'. The research has been published in the Royal Society journal Open Biology.

"Land snakes and many lizards have small raised structures on the scales on their heads – called scale sensilla – that they use to sense objects by direct touch," says lead author Jenna Crowe-Riddell, University of Adelaide PhD student.

"We found that the scale sensilla of sea snakes were much more dome-shaped than the sensilla of land snakes, with the organs protruded further from the animals' scales, potentially making them more likely to be able to sense vibrations from all directions. We also found that scale sensilla on some of the fully aquatic snakes covered a much higher proportion of the scales' surface.

"We believe sea snakes use these organs to sense objects at a distance by 'feeling' movements in the water. This hydrodynamic sense is not an option for land animals. In water, a new way of sensing the environment becomes possible."

Sea snakes evolved from land-living snakes, taking to life in the sea between 9 and 20 million years ago. They spend the majority of their lives at sea: hunting fish, swimming and diving using a paddle-shaped tail, and coming up to the water's surface to breathe air. Although they can also see, little is known about the underwater sensory perception of the snakes.

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