Meet Australia’s sea snake queen

Australia is home to many species of sea snakes and scientist Blanche d’Anastasi has the joy of studying them. Here, she tells us about what it takes to be a sea snake expert.
By Australian Geographic October 26, 2021 Reading Time: 6 Minutes Print this page

When and where did your love for sea snakes begin?

I wanted to be a vet, but my grades were not quite good enough. I got into an advanced marine science program at James Cook University, which turned out to be my dream degree. I started researching endangered sawfish during my year-long honours project. This emboldened my passion for sharks and rays, which I started a PhD on. 

I wanted to find out if human impacts on populations depleted their genetic resilience. But the genetic technology was not quite advanced enough at the time to pursue this. One day someone said to me, “What about sea snakes? They are disappearing.” I did some research, realised they are fascinating and are in trouble. 

Switching to sea snakes felt like hanging onto a boat in the middle of the ocean and just letting go, casting myself into unknown seas, with no funding and little knowledge of sea snakes! It turned out to be one of the most extraordinary decisions of my life. Now I get to share my passion for sea snakes and the ocean with the world, and to help conserve these precious things.

Do you have a favourite sea snake?

I can’t choose one! As a group, they are so magical! Sea snakes have bumps on their scales, called sensilla, which detect water vibrations. 

Olive sea snakes have light sensors in their tail and complex social behaviours. Annulated sea snakes have a dense network of blood vessels that act like fish gills, transporting oxygen collected through their skin, into their brain. 

Research has shown that turtle-headed sea snakes seem to have friends that they hang out with from year to year. These friendly little caviar eaters get their name from the fused scales on their upper lip, used to scrape off fish eggs from rocks, that make their face look kind of like a turtle. Horned sea snakes have ornate scales on their eyes that make them look like little sea dragons. I hypothesise that the ornate scales act like a giant radar dish for sensing the movements of the gobies that they are stalking in burrows! North-western mangrove sea snakes and black-ringed mangrove sea snakes come from the sea to hunt crabs and gobies on mudflats and in mangroves.

What’s your favourite sea snake behaviour?

Sometimes I replay the extraordinary things that I have seen in my mind like a video. There are few things that rocked my water-woman-sea-snake-scientist world!

I was diving in the crystal-clear waters of Scott Reef, way offshore in the Timor Sea, with the Australian Institute of Marine Science. There were quite a few olive sea snakes around. A big female olive cruised in with confidence. I watched with fascination as she made an arc with her body and used it to give other snakes a shove. Then she gave me a shove! I think she was advising me, “I am the Queen of this domain, it’s time for you to move on.”

Another one was when I witnessed secret, pregnant sea-snake business. It was December. The subtropical waters of Gathaagudu/Shark Bay were warm, like bath water. I was in the water one evening on dusk, wrapping up for the day, when I witnessed something extraordinary. Five big pregnant Shark Bay snakes showed up. They were relaxed as they cruised around jetty structures, swirling around, gently touching as they glided past one another. They did this daily. This was the moment that I realised how socially complex they are – they were here on secret pregnant snakey business. I still don’t quite know what their secret business was, but it’s okay for some things to remain a mystery. I am extraordinarily privileged to have witnessed this.

Related: The weird world of Australian sea snakes

What are some of the biggest myths about sea snakes?

Sea snakes are venomous elapids, with fixed front fangs in the front of their mouth and flip-top heads. Contrary to the global myth, they do not have small mouths and small fangs. But there is a simple equation – leave them alone and they will leave you alone.

Can you name one of the proudest moments of your career?

I am deeply passionate about putting science and conservation together. The standout moments for me are when I get to use science to contribute to conservation.

Recently, I co-wrote a report on a little-known place called Exmouth Gulf in Western Australia. Our report showed that it is an extraordinary biodiversity reservoir that helps sustain one of the healthiest coral reefs left on the planet, the world-renowned Ningaloo Coast World Heritage Area. It’s home to over 780 fish species. It’s a quiet place where humpback whales can safely nurse their calves and rest. It’s a sea snake biodiversity hotspot too. There are dugongs, critically endangered sawfish, turtles, manta rays… the list goes on. We know that big industry wants to industrialise this remote wilderness. By documenting the extraordinary value of this Mission Blue Hope Spot, we have shown that this place needs to be protected, not industrialised.

Founding the Australian Sea Snakes Citizen Science project was quite amazing too. We collect citizen-science records of sea snakes on our Facebook group. Records submitted to us led to a new depth record for sea snakes, at almost 250m. We are getting important data about reproductive behaviours and stranding patterns too. We are educating the public, wildlife carers and snake catchers about how to respond to sea snake strandings without harming fragile sea snakes, which are designed for life in the water and should never be head pinned or transported in water (put them on a wet towel).

Related: A guide to the sea snakes of Australia

What’s it like working out in the field with sea snakes?

When I first started working with sea snakes I knew little about them and my adrenaline levels would spike! As I learned to understand them better, I started to truly appreciate them. They are sublime, the way they glide through the sea with confidence, purpose and beauty. They are intriguing, especially when they interact with each other.

Working with them, and for them, in my quest to conserve them, is one of the greatest privileges of my life. Hanging off the back of a boat on a rope, gliding over stromatolite reefs, coral reefs and seagrass meadows looking for sea snakes is quite extraordinary too. Reef sharks are hilarious when I tow over the top of them, they do a loop or two right where they are to try to figure out what is going on. I filled up my mask with water the first time I saw this, because I laughed at the cuteness of the shark’s loop-de-loops.

If you weren’t studying sea snakes, what do you think you’d be studying?

I would happily study anything in the ocean that is data deficient and declining, but probably sawfish and stingrays. Globally they are among the most data-deficient species and are highly threatened by climate change and coastal fisheries, just like sea snakes.

What would you love future research to focus on?

Sea snakes are hard to study. There are 60–70 species distributed in tropical and subtropical waters globally. We don’t know enough about half of these species to assess their conservation status. We need more people and more funding to study sea snakes. We need more innovative ways to do it too! The two big-picture research projects that could really help with conservation that stand out to me involve eDNA and remotely sensed habitat data. 

There are a couple of other dream projects that I want to do! I found a sea snake nursery ground during my PhD. I want to work with Traditional Custodians to characterise it and help figure out what we need to do to protect it. I also want to track the movement of the endemic north-western mangrove sea snake because we know almost nothing about it and its whole geographic distribution is on the north-west shelf of WA – which is increasingly impacted, as a resource-extraction hotspot. There is so much work to be done!

What do you think it takes to become a sea snake expert?

Getting hands-on with sea snakes is the exciting part of sea snake research – it’s my favourite part! And it’s what most people are interested in. But it’s such a small part of what we do. For every month of field work, there is 6–11 months of office and lab work. If you want to work on sea snakes, you need to be passionate about getting hands-on with sea snakes and committed to the time and energy it takes to write the project proposal, get the government permits, do the lab work, data analysis, write up your findings and communicate this to other researchers, managers, fishers and communities.

You can follow Blanche on Twitter here.