Facts: The Bushy-Backed Nudibranch

The bushy-backed nudibranch is a species of sea slug that has a broad northern distribution in the cold temperate and polar ocean waters of the Arctic and Atlantic. These slugs are found from the Arctic Circle to at least New Jersey in the West Atlantic and France in the East Atlantic. Bushy-backed nudibranchs are characterized by two rows of bushy, highly branched structures called serrata along their back, giving them their name. The serrata primarily function as external gills. Coloration of these nudibranchs can vary a lot between individuals. Their body may be translucent grayish-white, white, pale pink, or yellow, and is often modeled with brown, red, orange, yellow, or green pigments. The front of their head has an oral veil, an expanded flap of tissue which contains branch projections. On the top of their head is a pair of sensory organs called rhinophores. The rhinophores are sheathed in tissue and these sheaths terminate in short branches. Between the branches at the end of the rhinophore sheaths are the ends of the rhinophores themselves, which have a ribbed, pinecone-like appearance. The body of these slugs is tapered to a point at the rear end. Most individuals are relatively small, commonly measuring around 1 or 2 inches, although much larger specimens, over 4 inches long, have been reported in deeper waters. Bushy-backed nudibranchs inhabit rocks, seaweed, hydroid colonies, mussel reefs, and other marine habitats. They can be found from the lower intertidal zone to deeper, subtidal waters, sometimes occurring at depths of several hundred feet. They are thought to mainly feed on hydroids. Hydroids are stinging animals that look like feathery plants. Juvenile bushy-backed nudibranchs may feed by grasping hydroids and sucking out their tissues, while larger individuals are capable of biting off and consuming entire polyps. Bushy-backed nudibranchs were previously thought to inhabit the Pacific coast of North America, but those sightings are now considered a separate species. For more marine facts, click the subscribe button!!