Despite large spider crab swarms, environmentalists are advising tourists to keep visiting Cornwall’s beaches and claiming that the crustaceans are not “venomous.”
In recent weeks, thousands of crabs have been seen covering the ocean bottom in well-known tourist destinations like Newquay, St. Ives, Falmouth, and St. Austell.
The spider crab gatherings were formerly uncommon in UK seas, but this summer has been “unusually spectacular” for sightings, according to Cornwall Wildlife Trust.
The higher numbers are probably due to climate change.
The trust insists that they are “totally safe to humans” and is enticing visitors to go watch the underwater show in action.
Matt Slater, marine conservation officer at the trust, refuted accusations that spider crabs bite with venom, saying to MailOnline: “They don’t bite at all and their pinch is not significant – it probably wouldn’t even scratch.”
I’ve devoted my whole professional life to educating people about fascinating aquatic creatures like spider crabs, he said.
They just aren’t poisonous, and rumours to the contrary might harm their image.
These creatures are really rare and perfectly safe for people to interact with.
Despite the many meetings we have seen in locations like St. Ives, this kind of behaviour is not often observed.
It was an incredible experience when I first watched it in Falmouth last year.
“If you are so fortunate to witness one, please go out, enjoy our shoreline responsibly, and marvel at these beautiful spider crab displays.”
For the purpose of identifying their behaviour and migrations, the Cornwall Wildlife Trust is also requesting that people report any sightings of spider crabs to them.
With a rise in population in the UK, these trends seem to have shifted recently.
The spiny spider crab, Maja brachydactyla, has been found this summer in Torbay, Wales, and various beaches around Cornwall, contrary to the claim made by Cornwall Wildlife Trust that it only had one verified collection of the species in 2021.
This year’s first reported sighting occurred on June 21 at Carbis Bay.
In the past, spider crab gatherings were more frequent in the Mediterranean Sea’s warmer waters, but marine experts now think that the increase in UK seas is a direct effect of global warming and rising sea temperatures.
“We hope that these widespread observations are an indication that spider crab populations are robust,” Mr. Slater said.
We’d be interested in hearing of additional meetings along Cornwall’s shoreline.
We still know so little about our waters, which are full of surprises.
Spider crabs resemble spiders thanks to their lengthy, spiky legs and one-meter long claws.
Each summer, these unusual organisms assemble in large numbers as they migrate from coastal waters that are deep to those that are shallow and split open their exoskeletons to develop a new outer shell.
Since they are so vulnerable when moulting, they band together to defend themselves from potential predators.
The spider crab mass moulting seemed to be something you’d see in a tropical location, but it’s taking place right here in Cornwall, said Katie Maggs, a BSAC snorkel instructor and volunteer with Cornwall conservation group Mounts Bay Marine Group.
“I feel very fortunate to have seen it for myself.”
People often tell me that if I didn’t share my movies, they would never have the opportunity to see our amazing marine life.
“I really feel very fortunate to be able to share the discoveries I made while snorkelling with others, and I’m hoping that doing so will inspire others to care for and understand our oceans.”