Velella velella


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Distribution: 
Oceanic worldwide in temperate and tropical seas.
Habitat: 
Floats at the sea surface.
Size: 
40-80 mm long, as adults.
Diet: 
Zooplankton and fish eggs.
Predators: 
Pelagic gastropods (snails).
Useful Facts or Characters: 

A clear, chitinous semicircular to triangular sail sticks up above the water with a blue float beneath made of concentric circles of gas-filled chambers. Small tentacles extend below the circular chambers.  The sail is angled left or right.

Natural History: 

Called  the "by-the-wind sailor."  Generally floats offshore but can be blown onshore in large numbers.