Wild Wednesday – Common Brittle-star
If you've ever peered into a rockpool or turned over a stone along the shore line, you may have caught a glimpse of something that looks more like living spaghetti than an animal. Say hello to the Common Brittle‑star, scientific name, Ophiothrix fragilis, one of our most abundant and most agile marine residents.
Unlike its close cousin the starfish, the brittle‑star doesn't crawl slowly along the seabed. Instead, it scuttles. With five long, flexible arms radiating from a small central disc, brittle‑stars move with surprising speed, rowing themselves along using snake‑like motions. If startled, they can vanish into a crevice in seconds.
Fragile by name, clever by nature
The “brittle” part of their name comes from their remarkable, if slightly alarming, defence strategy. When threatened, a brittle‑star can shed an arm to escape a predator. While the abandoned limb wriggles distractingly, the animal slips away to safety. Even better, that lost arm can grow back over time, making brittle‑stars true masters of regeneration.
A hidden underwater crowd
Despite rarely being noticed, common brittle‑stars can be found in vast numbers around the UK coast, from shallow rockpools to deeper offshore waters. In some places, thousands can carpet the seabed, their arms raised into the water column like a living net. This posture allows them to feed efficiently on tiny particles of food drifting past, including plankton and organic debris.
They play a valuable role in keeping seabed ecosystems healthy by recycling nutrients and helping to clean the water column - quiet workhorses of the marine world.
Not actually starfish
Although they look similar, brittle‑stars belong to a different group from true starfish. Their arms are sharply distinct from the central disc and are packed with joints, giving them their signature flexibility. Their mouth is tucked underneath the body, and they have no eyes or blood - instead, using seawater to move nutrients around.
What they lack in obvious features, they make up for in sensitivity. Brittle‑stars can detect light, chemicals and vibrations, allowing them to respond quickly to danger or food.
Why they matter
Because they are sensitive to changes in water quality and seabed disturbance, brittle‑stars are often used as indicator species by scientists monitoring marine health. Seeing plenty of them is usually a good sign that a habitat is thriving.
So next time you're exploring the coast or learning about life beneath the waves, spare a thought for the common brittle‑star. It may not be flashy or famous, but it's a brilliant example of how adaptable, and extraordinary, our local wildlife can be.
Read more here: Common brittlestar | The Wildlife Trusts