Uncovering The Truth About Sea Snakes

The sea snake is one of Australia’s deadly predators. About 30kms from land in the Dampier Marine Park, Western Australia, nature journalist Dr Ann Jones joins Environment Institute members Associate Professor Kate Sanders and Dr Jenna Crowe-Riddell.

In her brand new show ‘Dr Ann’s Secret Lives’ she joins scientists on location and in the field, in hopes of learning new perspectives and deeper understadnings of animals.

In episode 2, it’s all about sea snakes. There are over 60 species of sea snakes worldwide, orginating in Australia explains A/Prof Sanders.

“The only way to truly understand them is to get hands-on. That’s why we’re out here, in the dark, on a boat.” Says A/Prof Sanders

A/ Prof Sanders says that the historical evolution of the sea snake goes back as far as 10 to 15 million years ago, “they descended from terrestrial ancestors and what a successful evolutionary experiment, so these are now highly marine adapted species.”

She then highlights what makes them so special and how they differ from the land snakes “firstly swimming ability. All snakes are great swimmers but you can see the shape of the body here is something like a gymnast ribbon, which allows them to propel themselves efficiently through the water,”

“That's a really key trait which adapts into swimming and in the open ocean, the way that they flatten their body in this way is by reducing the size of the belly scales, we also have a paddle shaped tail.”

Dr Crowe-Ridell explains their DNA analysis process, by snipping a tiny bit off of the scales and then placing it into ethanol. The DNA analysis can tell the story of how these snakes evolved into so many species from just one common ancestor. They also use tags to follow the location, depth, and temperature of the sea snakes.

“so next we've got these pit tags. So, if we never catch her again, we’ll know who she is” says Dr Crowe-Ridell.

“It’s like a bar code that you would have similarly to a microchip on your cat or dog” says prof sanders  “It’s actually just the same technology”.

Dr Ann points out how the assumed perception of seas snakes are considered “dangerous” and “so vicious” however after spending time with them, she finds that idea is almost wrong.

A/Prof Sanders goes on to say “so many [sea snakes] are not aggresive but then others are, so it can be quite dangerous to assume what you know about [them]”

They also follow the underwater journey of a sea snake using acoustic tracking with PhD student, Laura Murray. As the day turns into night, they continue to wrangle snakes with hopes of catching as many species as possible.

Throughout the episode, the Ocelot sea snake is found a few times in the area. Dr Crowe-Ridell goes on to say “See, this species is so beautiful. It’s got this big round eye, and we think because they go deeper, they might need to let more light in..but we really don’t know that much about this species, but we catch a lot of them out here.” The team are surveying sea snakes in Dampier Marine Park in Western Australia.

They also wrangled the Olive-headed sea snake. “Well this one special because it's a specialist on plotosidae catfish, so not much eats those. In fact they’re even invasive in the Mediterranean, but here in Australia these guys specialise on them, it is pretty much all they eat.” Explains Dr Crowe-Ridell. “the fish has incredibly toxic spines so yeah basically nothing else can eat it out there,” making this sea snakes’ their only predator  . 

“it's got fangs right incredibly venomous like all the other see snakes. They’re tiny but sharp enough to pierce the flesh of the catfish.”

The work of both A/Prof Sanders and Dr Crowe-Riddell reflects how much of the ocean is unexplored, and how these animals are misunderstood. By studying these reptiles, they can undercover crucial ecological insight and challenge what we thought we knew about these veneomus creatures.

Their work is supported by a Australian Marine Parks grant aimed at protecting the biological and cultural values of sea snakes under climate change in Dampier Marine Park.

Stream this and all episodes of brand-new Dr Ann's Secret Lives on Australian Broadcasting Corporation (ABC) iview, or Tuesdays 8.30pm on ABC TV.

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