Sea snakes, which are subtly named for their tendency to swim around the ocean and in other bodies of water, have long been known to take shallow dives. On the other hand, sea snakes don’t have gills and they can’t scuba dive like a water anole, and so they still need to return the surface on occasion to grab a breath of fresh air.
Image Credit: INPEX-operated Ichthys LNG Project
Given the circumstances, scientists were particularly astonished when they obtained video footage of sea snakes diving well into the ocean’s mesopelagic zone, a region residing more than 200 meters (656+ feet) below the ocean’s surface. The findings were just recently published in the scientific journal Austral Ecology.
"Sea snakes were thought to only dive between a maximum of 50 to 100 meters because they need to regularly swim to the sea surface to breathe air, so we were very surprised to find them so deep," elaborated study lead author Dr. Jenna Crowe-Riddell from the University of Adelaide's School of Biological Sciences.
"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, but I never suspected that this ability allows sea snakes to dive to deep-sea habitats," she added.
The video footage purportedly showed a couple of sea snakes off the coast of Australia, both of which were the same species, diving to depths of 245 meters (804 feet) and 238 meters (781 feet) respectively. These are precedent-setting numbers; the previous sea snake diving record was just 133 meters (436 feet) beneath the surface.
But what were the sea snakes doing at such great depths? According to the researchers, it appeared as if they were foraging for food by poking their heads into burrows made in the sandy seafloor. On the other hand, this raises more questions than it answers, especially given the dimly-lit conditions at this depth of the ocean that would make seeing prey very difficult.
It’s possible that these sea snakes have an entirely different sense for detecting prey that we know nothing about, or perhaps they have much better eyesight than we give credit for. Moreover, the researchers aren’t sure what types of prey the sea snakes were eating, which only adds to the growing list of questions that we now have.
Armed with new knowledge about sea snake diving habits, you can bet that researchers will be spending more time studying the animals to understand their behavior better. On the other hand, it could be some time before we officially answer some of the latest questions concerning their deep-diving lifestyle.