Nudibranchs are sea slugs without shells. Many nudibranchs are brightly colored, and are the underwater analogs of butterflies. The name Nudibranch means "naked gills" and most nudibranchs have plumed gills outside the body.The vast majority of nudibranchs also have pairs of sensory organs called Rhinopores on their heads (clearly visible on this animal).

Nudibranchs propel themselves forward by muscular contractions of a fleshy foot. Nudibranchs protect themselves with camouflage or chemical warfare. Bright colors can be used to warn predators that they are toxic or noxious. Some Nudibranchs ingest the nematocysts (stinging cells) of their prey and use these cells they as weapons against predation. Some secrete acids which are toxic. Some Nudibranchs have life cycles which last only 6 weeks; others live for over a year.

Photographed in the Solomon Islands