Mysterious Sea Creatures Wash Up on Barcelona Beaches

Velella Velella
A dead Velella velella sits on the sand in Pebble Beach, California, U.S., on August 26, 2014. REUTERS/Michael Fiala

Barcelona's beaches have been carpeted with thousands of mysterious jellyfish-like creatures, turning the city's white sands a rich shade of blue, reported.

Fortunately the animals, identified as Velella velella, are relatively harmless to humans, making this invasion more of a natural marvel than a toxic emergency.

Velella look like jellyfish, but are actually floating colonies of microscopic hydrozoans—tiny predatory creatures that generally live far offshore in open waters. Velella have small, stiff, sail-like structures to harness the power of the wind and allow them to travel across the water in search of plankton and other small prey.

In the summer months, Velella generally move closer to shore as water temperatures rise. Here, they are vulnerable to sudden strong winds, and the colonies can end up closer to land than intended resulting in local shorelines painted blue. Known as "By-the-Wind Sailor" or "Sea Raft" in English, stranded Vellela colonies are a common sight on the western U.S. coast.

Such incidents are rare in the Mediterranean, but strong winds and sea currents over the weekend have been blamed for the thousands of Vellela found along the Catalan coast.

Velella are related to the deadly Portuguese Man O' War siphonophore, whose long tentacles can deliver an excruciating sting. Unlike Man O' War, Velella can no longer sting when washed up dead on beaches.

However, scientists recommend steering clear of the mysterious animals as they do still carry a mild neurotoxin. People should be especially careful to avoid touching the creatures and then touching their eyes, as this could be harmful.

According to biotechnologist Lluis Montoliu, Velella are abundant in spring and can be mistaken for small mussels at a distance. A tweet sent out by Barcelona's port police explained that Velella often find their way to Barcelona towards the end of April as a result of inflowing Atlantic waters after stormy weather.

They may be beautiful at first, but as the Vellela begin to decay they will give off an unpleasant fishy smell. And with thousands lying dead on the Catalan beaches, the shorelines could stink for days to come. Barcelona's city council has confirmed that a clean-up operation is underway, so hopefully residents will be spared the worst.