Millions of blue jellyfish-like creatures known as Velella – By-the-wind Sailor, have washed up along the North American West coast, from southern California to British Columbia.
The creature is known as the “by-the-wind sailor” but its scientific name is Velella Velella.
“The numbers, if you extrapolate, are awe-inspiring,” — Sightings have been reported in California, Oregon and Washington states, as well as across the border on Canada’s West Coast.
The creatures are carnivorous and sting, but usually not enough to harm humans.
They normally live several miles off the coast, and once they wash ashore, they die and decompose, becoming cellophane-like. The National Geographic said experts have been trying to explain the cause of such “blooms”.
Possible reasons range from ocean currents and winds to over-fishing, which deprives jellyfish of some of their favourite foods, it said.
Velella is a cosmopolitan genus of free-floating hydrozoans that live on the surface of the open ocean. There is only one known species, Velella velella, in the genus. Velella velella is commonly known by the names sea raft, by-the-wind sailor, purple sail, ittle sail, or simply Velella.
These small cnidarians are part of a specialised ocean surface community that includes the better-known cnidarian siphonophore, the Portuguese man o’ war. Specialized predatory gastropod mollusks prey on these cnidarians. Such predators include nudibranchs (sea slugs) in the genus Glaucus and purple snails in the genus Janthina.
Each apparent individual Velella velella is in fact a hydroid colony, and most are less than about 7 cm long. They are usually deep blue in colour, but their most obvious feature is a small stiff sail that catches the wind and propels them over the surface of the sea. Under certain wind conditions, they may be stranded in their thousand on beaches.