Found along Atlantic coasts from Norway to Senegal, Common Starfish are adaptable and remarkably resilient. Lose an arm, or even be cut in half, and they can regrow what’s missing!
They also play a key role in the food web as the predators of mussels, barnacles and other shell‑forming animals. They feed by pulling the shells open with their arms and inserting their stomach into the shell. The starfish releases powerful digestive juices that break the animal down, before reabsorbing their stomach full of the shellfish soup.
In healthy ecosystems, this predation keeps mussel populations in check and allows a diverse mosaic of seabed habitats to develop – creating space for kelp, sponges and many other species to return. Starfish help prevent any single species from dominating and so support the natural complexity of the seabed.
But balance is everything! Like all key players in an ecosystem, starfish numbers are themselves regulated by predators such as crabs. If their predators are lost, starfish can become over‑abundant and tip the system out of balance. For this reason, our research and monitoring programme investigates multiple levels of the food web, with a particular focus on crab populations, whose presence not only supports sustainable fisheries but helps regulate starfish numbers and supports wider marine recovery.
Last summer, during a dive, I saw multi-layered mussel beds unlike anything I’d ever seen in Sussex. The multi-storeyed mussels were covered in starfish feeding in numbers I’ve never observed anywhere else in the world. It was the most abundant marine life I’d ever observed in our waters and it gave me hope for the continuing recovery – our next challenge is healthy populations of starfish predators!
Written by guest author, George Short - Project Coordinator, Sussex Kelp Recovery Project/Sussex Wildlife Trust