The crustaceans are instantly recognizable by their long legs and pincers and have a venomous bite that is poisonous to their prey but harmless to humans. Their presence on Porthgwidden beach was enough to deter many bathers from entering the sea. However, Kate Lowe, a marine photographer captured the event just days after a snorkeler was bitten by a blue shark during an excursion off Penzance. Spider crabs have been spotted congregating in St Ives, Cornwall to shed their shells before returning to the depths. Photo: @cornish.coast/BNPS Kate said: “I go snorkelling most times of the year but I’ve never seen spider crabs in such numbers. When we got to the beach, it looked like there were a lot of dark rocks under the surface. “But it turned out there were thousands of crabs just two or three feet into the water. It was really incredible, it was knee deep. I was able to float in the water above them and tried not to step on them. “Many tourists were screaming at the sight of them. Their shells were just floating around.” Experts say that although it is not unusual to see them in British waters, mass gatherings are becoming more common in the summer due to rising sea temperatures linked to the climate crisis. Spider crabs – Hyas araneus in Latin – usually congregate in huge numbers in shallow water to protect themselves from predators while they wait for their new exoskeletons to harden and harden.
