Common Sea Star

Photo: Anne Schlösser · CC BY-NC

Common sea stars aggregate in large numbers across the cave floor and lower walls at Gjógv, feeding on the dense beds of blue mussels and barnacles that grow wherever there is sufficient light near the entrance. In cold, productive North Atlantic water they grow to exceptional size, with individuals spanning 50 centimetres across not uncommon in protected cave environments. During seasonal mass spawning events, the water inside the cave becomes milky with gametes — a dramatic chemical signal that triggers synchronised reproduction across dozens of individuals within minutes.