What is this mysterious tide? Millions of blue, alien-like creatures blanketing US beaches

What is this mysterious tide? Millions of blue, alien-like creatures blanketing US beaches

From Oregon to California, masses of alien-like blue creatures are washing up on rocky beaches. These are called Velella velella, small colonies of organisms sporting a sombrero-esque fin atop and tentacles dangling down.

If reports are to go by, this spring, millions have been spotted along the US west coast, much to the surprise and delight of beachgoers who eagerly shared footage on social media. Referred to as a ‘blue tide,’ this phenomenon occurs in most springs, though not always with the same abundance.

Despite resembling a single organism, Velella, also known as by-the-wind sailors, are actually colonies of creatures from a class called hydrozoa that use the wind for speed. Spending most of their lives in the open ocean, they navigate using tentacles that sting fish larvae or zooplankton, yet pose no threat to humans. While similar to coral in their colonial structure, such encounters on land are rare, notes a doctoral student at the Scripps Institution of Oceanography.

Various theories have been put forward to explain the brilliant blue colour of these creatures. Living at the air-ocean interface offers them few hiding spots from predators like the mola mola ocean sunfish, which consumes Velella. Their colour may aid in camouflaging among waves or serve as protection from UV rays.

Living for months and travelling extensively around the Pacific gyre, Velella typically travels down the coast of California to Central America, then across to Japan and back, gliding along the surface akin to kite surfers.

Experiencing boom-and-bust cycles during their journey, Velella populations surge when ample food is available, leading to mass strandings on shore, often in spring and sometimes in fall.

Despite frequent encounters, Velella remain relatively unstudied in science, partly due to their surface-dwelling nature. Challenges in recreating their oceanic habitat in captivity hinder research efforts, leaving us with less knowledge compared to submersible jellyfish.

However, further investigation is required to confirm these hypotheses, requiring extensive studies of the organisms in their natural habitat.