Slideshow: Meet the Neuston, the Diverse Organisms Living at the Ocean’s Surface


     The Portuguese man-of-war (<em >Physalia physalis</em>)

© Denis Riek

The Portuguese man-of-war (Physalia physalis) is among the most recognizable members of the neuston, relying on long tentacles and a powerful sting to paralyze prey in the open sea.


© Denis Riek

Blue buttons (Porpita porpita) are made up of tiny, colonial hydrozoans branching from a central, rigid disc. Each hydroid in a colony performs a different function, such as feeding, defense, or reproduction.


     The violet sea snail (<em>Janthina janthina</em>)

© Denis Riek

The violet sea snail (Janthina janthina), shown here covered in barnacles, is blind and cannot swim, relying on a raft of mucus bubbles to suspend itself at the surface.


     The by-the-wind sailor (<em>Velella velella</em>)

© Denis Riek

The by-the-wind sailor (Velella velella) consists of a single polyp with a rigid sail that harnesses wind as the animal drifts on the open ocean. Scientists are unsure why, but the sails of some sailors orient left, while others orient right. 


© Denis Riek

Blue sea dragons (Glaucus spp.) are pelagic nudibranchs that feed on many other types of neuston, including the Portuguese man-of-war. The sea slugs store the man-of-war’s toxins in external structures called cerata, giving them protection from predators.


     This buoy barnacle (<em>Dosima fascicularis</em>)

© Denis Riek

This buoy barnacle (Dosima fascicularis) creates its own styrofoam-like float, from which it hangs downward into the water and feeds on plankton drifting by.


     Water skaters (genus Halobates) left, and 
their eggs (the orange specks glued to a piece of plastic in the image at right)

Water skaters (genus Halobates) may actually benefit from the glut of plastic accumulating in their habitat, as the insects require a hard substrate on which to lay their eggs (the orange specks glued to a piece of plastic in the image at right).

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