Taxon Description (Wikipedia)
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...
full article at Wikipedia
