The jellyfish are about the size of a mussel

It is thought they are mainly of the "By-the-Wind Sailors" variety, from the same family as the Portuguese Man o' War, which can deliver a nasty sting.

Coastguards at Brixham are warning people not to handle the jellyfish, which are also known as Velella Velella and are about the size of a mussel.

They do give off a minor sting which may cause an allergic reaction.

Taking reports

Annie Westcott from the Brixham coastguard station said: "People are likely to see them. There are absolutely thousands upon thousands of them - people will think we're being invaded.

"They actually look like mussels from a distance because they are a similar colour, a purple-blue colour.

"We're just saying to the public, if you do go down to the beaches, don't handle them but we're quite happy to take reports about them.