Beach walkers are being warned to not to touch a mass of jellyfish which have been washed up along the Pembrokeshire coastline.

The jellyfish called Vellela Vellela or By-the-Wind-Sailor are rarely seen in British waters and are more common along the coastline of southern California.

They do sting but they are not thought to be harmful to humans

Len Mullins Pembrokeshire County Council

The local authority have told the public not to touch them as they can sting, even when they are dead.

The creatures are thought to have been swept on to beaches, forming lines of up to 60 feet between West Dale and Gellyswick, by westerly winds.

The dead and dying jellyfish were discovered after Pembrokeshire County Council received reports of a blue substance.

Len Mullins from Pembrokeshire council said: "They do sting but they are not thought to be harmful to humans.

Tests

"To be on the safe side we would advise people not to pick them up."

Some of the jellyfish have been sent to a laboratory for further tests.

Pembrokeshire council is seeking advice from the Environment Agency and the Countryside Council for Wales on ways of disposing of the jellyfish.

Mr Mullins added: "We are going to leave them for tonight.

"It may well be that the tide comes in and washes them away by the morning."

The creature gets its nickname from its 'fin' which allows it to catch the wind and sail on the surface of the water.

Stinging tentacles

Occasionally, huge numbers wash up on the beach along the California coastline.

The jellyfish has numerous reproductive tentacles and a single feeding tentacle which is suspended from a plastic-like disc.

The edge of the disc is fringed with stinging tentacles, which it uses to catch its food.