May 20, 2011

Velella jellyfish








Something different on Lahinch beach today.
Velella is a genus of free-floating Hydrozoans that lives on the surface of the open ocean, worldwide, and is commonly known by the names by-the-wind sailor, purple sail, little sail, or simply Velella. The most common, and perhaps the only species encountered is Velella velella.
These small cnidarians are part of a specialised ocean surface community that includes the cnidarian siphonophore Portuguese Man o' War and some specialised molluscan nudibranchs (sea slugs), including Glaucus and the purple snails Janthina, that prey on them. Each Velella is 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 can become stranded on beaches in the thousands.

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