New record set for deep-diving snakes in the ‘twilight zone’

An unidentified species of sea snake swimming at 245 m below the surface of the ocean in Australia’s North West Shelf. Image from video footage taken industry-operated ROVs.  Image credit: Inpex

An unidentified species of sea snake swimming at 245 m below the surface of the ocean in Australia’s North West Shelf. Image from video footage taken industry-operated ROVs.

Image credit: Inpex

 Sea snakes are thought to only dive between a maximum of 50 to 100 metres because of their relatively small size and their need to regularly swim to the sea surface to breathe air. Sea snakes were recorded swimming at 250 meters by Industry-operated remotely operated vehicle or ‘ROV’ off Western Australia in the North West Self, smashing the previous diving record of 133 metres held by sea snakes.

Oceanic depths between 200 and 1000 metres encompass the mesopelagic zone, sometimes called the ‘twilight zone’ because only a small amount of light reaches that depth. Sea snakes can cope with diving sickness known as ‘the bends’ using gas exchange through their skin, but we never suspected that this ability allows sea snakes to dive to deep-sea habitats!

Snakes were filmed in 2014 and 2017 using ROV undertaking work for the INPEX operated Ichthys LNG Project. Both snakes appeared to belong to the same species but could not be identified from the images. Further exploration is needed to resolve the physiological capabilities and taxonmy uncertainty of these deep-diving sea snakes. Our study highlights the importance of industry-university collaboration in monitoring poorly-surveyed populations of sea snakes.

 

Read more in our publication in Austral Ecology. Please contact me if you’d like a copy of the paper.

Crowe-Riddell, JM, D’Anastasi, B, Nankivell, JH, Rasmussen, AR, Sanders, KL(2019) ‘First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200m)’, Austral Ecology, 44, 752-754. doi: 10.1111/aec.12717.

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