They are the rock stars of marine invertebrates.  Fabulous and flamboyant, they live fast, reproduce furiously and die young.   But they are also evolutionary marvels:  chemical wizards, crafty thieves, sly poisoners—and the sexiest of intertidal residents.

Beachcombers call them sea slugs. Marine biologists categorize them as nudibranchs (rhymes with swanks and translates as “naked gills”), relatives of snails that shed their shells early in life. While many aquatic creatures rely on camouflage, nudibranchs flaunt eye-popping colors—regal purple, hot pink, electric blue, neon yellow—and exuberant patterns.