Residents of America's west coast are baffled by the appearance of translucent jelly-like sea creatures washing up on local beaches.

Beach-walkers have noted their growing presence on Pacific shores in recent months. Blooms of the tiny sea creatures were spotted off-shore earlier this summer but are now visible on land.

"We've had other critters of course but I don't remember these guys and there's just tons of them," said resident Phyllis Ham to local station KGW.

The organisms, known by scientists as pyrosomes, have an unusual pink appearance and are usually around 1cm in length. They are individually made up of hundreds of cells.

Although harmless to humans their appearance has concerned the scientific community. Typically Pyrosomes appear in warmer waters but have now popped up in Alaska and other locations in America's Pacific Northwest.

The University of Oregon has conducted extensive research into the phenomenon and say a build-up of the organisms could be harmful to other sea-life. Last year researchers at the university videoed large numbers of the creatures floating in the sea but the appearance on the shore is far more unusual.

"The one thing that might be of concern around here is that if there's enough of these and they sink to the bottom, it could maybe cause a dead zone," said marine biologist Jim Young.

The creatures are likely to disintegrate over the coming weeks and could leave a rather slippery and smelly mess, say experts.

Sea pickles
The strange translucent blobs washing up on US shores. KGW