Spanish shawl nudibranch on kelp off Santa Catalina Island, Channel Islands, California

© WaterFrame/Alam

One stylish slug

Today we're meeting one of a motley group of sea slugs called the nudibranchs (rhymes with 'thanks'), known for their unique, often complex shapes and neon-bright colours that help discourage predators. The Spanish shawl's fire-orange mane is made up of tendrils called cerata that mainly act as gills. But that mane also retains venom from the slug's prey—sea anemones—treating any would-be devourers to a painful sting. Should a ravenous sea star disregard these defenses and get too close for comfort, the Spanish shawl has a Plan B: By flapping its whole 5- to 7-centimetre body like a gelatinous wing, the nudibranch can flutter into open water for a quick escape.