Thousands of venomous spider crabs swarm British beach in spectacular sight

Holidaymakers have been handed a warning after thousands of venomous spider crabs have swarmed a tourist hot-spot in Cornwall.

It comes just days after a snorkeller claims they were bitten by a shark and the Cornish coastline was flooded with jellyfish.

Now, a beach in St Ives has now been overrun by the mass of the crustaceans.

They have gathered in the shallow water at St Ives in Cornwall to shed their shells before returning to ocean.

Bathers at Porthgwidden Beach was not totally put off and some did take the chance to swim above the carpet of crabs to view the hair-raising spectacle.

Spider crabs, that are instantly recognisable for their long legs and pincer claws, have a venomous bite that is poisonous to their prey but harmless to humans.

The crabs can normally be seen close to the shore in summer and autumn as the crabs rally together. They gather together to protect themselves from predators.

While it is not unusual to see them in UK waters, mass gatherings like this one are becoming more common in the summer due to rising sea temperatures.

Once the crabs grow another tough outer shell they will disperse to depths of 300ft and paddling will become far more appealing.

Kate Lowe, a marine photographer, captured the event in the same week a woman snorkeller was bitten by a blue shark further around the Cornish coast, off Penzance.

Kate said: “I go snorkelling most of the time throughout the year but I have never seen spider crabs in such numbers.

“When we turned up at the beach it looked as though there were lots of dark rocks under the surface.

“But it turned out that there were thousands of crabs just two or three steps into the water.

“It was just really incredible, they were only knee deep. I was able to float on the water above them and tried not to step on them. A lot of the tourists were squeling at the sight of them.

“Their shedded shells were just floating around.”

Spider crabs are popular around Cornwall and are often spotted by scuba divers in the area around the summertime. The unique crabs are known for their spiny legs and their claws can span up to one metre.

In recent years, the population of spider crabs seems to have grown. This is due to climate change and sea temperatures warming.

The population growth is expected to continue in years to come.