Unusual jellyfish wash up on north coast beaches

Creatures closely related to the Portuguese man o' war have been discovered washed up on beaches along Northern Ireland's north coast.

These vibrant blue marine organisms, known as Velella velella or By-the-Wind Sailors, captivate onlookers with their sail-like structures that propel them across the ocean's surface.

Typically found floating on the sea, these creatures have been driven ashore by recent strong winds and shifting currents.

Dr Jonathan Houghton, a marine biologist at Queen's University Belfast, told BBC News NI they are "quite different from the usual jellyfish you might find stranded on beaches".

"These small, oval-shaped organisms, about 5-8cm long, belong to a group called Hydrozoa," he said.

"They possess a unique sail on top and drift with the wind".

While By-the-Wind Sailors typically strand during the spring and early months of the year, the extent and frequency of these events can vary, depending on wind patterns and ocean currents.

"This phenomenon is often amplified by major storm systems in the southern US and the Caribbean, which increase drift across the Atlantic Ocean," Dr Houghton told BBC News NI.

"There is usually a time lag, with major strandings of By-the-Wind Sailors occurring a few weeks after storm systems subside".

Despite their benign nature, marine experts advise against handling the creatures as they can cause minor skin irritation.

"By-the-Wind Sailors feed on plankton and live entirely on the surface," Dr Houghton added.

"Their prey are usually small, so they only have a mild sting that is generally harmless to humans, unlike some true jellyfish, which can have painful stings for capturing larger prey".

Native to the Azores in the mid-Atlantic, these fascinating creatures which resemble jellyfish, are actually colonies of tiny individual organisms working together in harmony.

Most will likely be washed back out to sea with the next high tide or decompose naturally on the shore.