Tail photoreception: Discovering a novel sensory system in Australian sea snakes

HSF 15/10 | Amount: $ 42,100 | Project Leader: K Sanders | Project Period: Jul '15 - Jul '17

A project undertaken at the School of Biological Sciences, University of Adelaide, and supervised by Dr Kate Sanders

The ~60 species of viviparous sea snakes comprise the world’s only fully aquatic marine reptiles. The group evolved in Australia (from our venomous land snakes) and displays a spectacular array of derived adaptations. Among the most remarkable of these traits is the photoreceptive tail of the olive sea snake, Aipysurus laevis. This trait was first described in 1990 (Zimmerman & Heatwole, Copeia 1990(3): 860-862) using behavioural studies to verify observations by night divers: sheltering olive sea snakes retract their vulnerable tail paddles in response to torch light.

Figure 1. PhD student Jenna Crowe-Riddell collecting a Stokes’ sea snake, Hydrophis stokesii
Figure 1. Aipysurus and Hydrophis species collected for behavioural studies and tissue sampling, Broome 2015

Whether tail photoreception is found in other sea snakes, and the genetic and physiological mechanism of its operation, is unknown. Our study aims to integrate:

  1. behavioural tests of tail photoreceptivity in captive sea snakes of previously untested Aipysurus and Hydrophis species,
  2. sequencing of skin transcriptomes to identify visual cycle genes expressed in the tail, and
  3. scanning electron microscopy and immunocytochemistry of tail skin biopsies to locate the cells and cellular structures involved in photoreception.

A video of the tail withdrawal response from our behavioural experiments may be viewed here