The carpet of crabs gathered in the shallow waters of St Ives is a sight that is becoming increasingly common in summer due to rising sea temperatures. Spider crabs are instantly recognizable by their long legs and claws and have a venomous bite that is poisonous to their prey but harmless to humans. While their presence on Porthgwidden Beach was enough to deter many bathers from entering the sea, some took the opportunity to snorkel above the mass of crustaceans for the hair-raising sight. Once the crabs shed their shells, they return to depths of 300 feet, leaving the water clear for those hoping to paddle the waters. Kate Lowe, a marine photographer, captured the incident in the same week that a female snorkeler was bitten by a blue shark further up the coast of Cornwall, off Penzance. Kate said: “I go snorkelling most times of the year but I’ve never seen spider crabs in such numbers. Image: Pic: KateLowe/BNPS Image: Pic: KateLowe/BNPS “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 squealed at the sight. “Their shells were just floating around.” Image: Photo: KateLowe/BNPS Spider crabs – Hyas araneus in Latin – usually gather in huge numbers in shallow water to protect themselves from predators.