All aboard the slug bus! This little kelp crawler is a Cockerell’s dorid nudibranch sea slug—and tucked away in the slug’s bulby branches is a red commensal scale worm along for the ride!
Cockerell’s dorids (Limacia cockerelli) feed on carpets of small animals known as bryozoans—their orange color derives from pigments in their food. Red commensal scale worms (Arctonoe pulchra) are avid hitchhikers that use sea stars, snails and slugs as convenient craft services to their next feeding ground.
The worms don’t bother the slugs, save for occasional pokes of the slugs’s gills that send the nudibranch into ticklish winces. The slug here is about an inch / three cm long, and the buddy pair was spotted just off the back deck of the Aquarium!