By the wind sailor

Velella velella

Family Porpitidae - hydroids

Body made of flexible chitin (cellophane-like texture); color is aqua-green to blue to violet; base float is oval with concentric rings (representing air tubes) on the surface; above float is an erect, triangular "sail" projecting at an angle; below the float around the edges are short tentacles; smaller tentacle-like objects on lower surface; in the center a small mass hangs down where the mouth opening is.
Similar Species
Fairly unique; similar to the blue button Porpita porpita but P. porpita is more round, usually green and has no sail.
Gulf, floats on the surface
Maximum Size
10.2 cm (4 in) long, 7.6 cm (3 in) wide and 5.1 cm (2 in) high.
Other Common Names
Previous Scientific Names