I found my first encounter with sea worms a little terrifying. I got into studying them because I was fascinated by a question: how can something as simple as a worm living in the mud in an estuary in Newcastle know exactly what day of the year it is, so that the whole population is able to reproduce on the same day?
So in the first days of my PhD, I visited a worm farm in Newcastle where they were growing worms to sell as fishing bait.
I was encouraged to plunge my hand into a large tank of squirming mud. As soon as I put my hand in, I realised why the mud was squirming: it was a writhing mass of ragworms.
Ragworms are quite big. They can grow up to 3m long and are about as thick as your thumb. They have teeth – and they bite.
Watching me, waiting for me to scream, were all these tough-looking geordie lads. So I didn’t make a sound.
But internally, I was definitely screaming. There were thousands of worms in that tank. It felt as if I was touching wriggling spaghetti and that night, I dreamed I was eating spaghetti that turned into worms in my mouth. I still sometimes have that dream – but thankfully, in my whole 25 years of working with worms, I’ve never been bitten. And when I started studying these animals, I became more and more fascinated by their wonderful weirdness.
There are more than 10,000 different species of worm, with many different adaptations. They can be all sorts of colours and are often very iridescent. One of the most beautiful worms is the Christmas tree worm, which you see on coral reefs looking like little brightly coloured Christmas trees. They’re sedentary and they don’t have any teeth.
All the marine worms I work on are “polychaetes”, which means “many feet”, in reference to their – in some cases – hundreds of beautiful, paddle-like feet, which enable them to swim and burrow into mud efficiently.
When I talk to children about marine worms, I try to convince them that worms are better than sharks because worms are able to completely regenerate any section of their bodies, including their heads. And not all worms are victims: some are ferocious predators of fish themselves.
In Samoa, people eat sea worms – they are treated as a delicacy. But I haven’t tasted one and I have no desire to do so.
A large part of my research is, first, trying to understand the impact that human activities have on worms and second, the important jobs worms do for healthy ecosystems. Without worms and other marine animals living and burrowing in the mud, recycling nutrients, there wouldn’t be enough nutrients in the surface ocean for photosynthesis to happen.
Worms are also food for all sorts of fish and birds, and we’re polluting them: we mimicked the levels of cocaine and antidepressants that were measured in the mud in Bristol harbour in a lab experiment and looked at how that affected worms’ behaviour. The worms stopped eating, lost weight and stopped burrowing into the mud.
And nowadays, if we collect worms from pretty much anywhere in the world, we’ll find plastic in their stomachs.
At the moment, as part of the Convex Seascape Survey, I’m looking at how worms influence carbon sequestration into sediments. We want to know if a healthy seabed full of healthy worms is better for keeping carbon locked away and for carbon cycling processes. So better protecting worms on the seabed could have much wider implications than just biodiversity – it could be a small part of the solution to the climate emergency.