Facts: The Horned Nudibranch

The horned nudibranch is a colorful sea slug that inhabits the Pacific Ocean. These slugs are primarily found from southern Alaska to California. Horned nudibranchs are part of a group of sea slugs called eolids. Eolid nudibranchs are covered with frilly, tentacle-like serrata. The serrata help them breathe and defend them from predators. Horned nudibranchs can feed on stinging animals like anemones and hydroids. Like other eolids, they can collect and store the stinging cells from the animals they consume. The stinging cells pass through the nudibranch's digestive system without harm, and get stored in the tips of the serrata. Horned nudibranchs typically have a milky-colored body. There are electric blue lines down each side of the big pair of tentacles on their head. An orange line originates from the head region and trails down toward their middle with electric blue edges. Their body tapers to a fine point. Their serrata vary in coloration from translucent white to orange, with a notable white central core and a bright orange tip. On top of their head is a pair of sensory organs called rhinophores that serve to help detect smells in their environment. Horned nudibranchs mainly feed on hydroids and small anemones, but they will also eat a variety of other small organisms. They are found from the low intertidal zone to depths of about 122 feet. They may be found on rocks, mudflats, pilings, and in tide pools. They can grow to about 3.25 inches long, but they are usually much smaller in tide pools. Horned nudibranchs can be easily mistaken for a similar species that also lives along the Pacific coast, called the southern opalescent nudibranch. However, unlike the horned nudibranch, this species does not have white lines on their serrata. Horned nudibranchs are known for their aggressive nature, both to other horned nudibranchs and to other sea slug species. Biting and lunging among individuals is normal, especially during the mating season. Like other nudibranchs, they are simultaneous hermaphrodites, possessing both male and female reproductive organs. They lay their eggs in clusters attached to rocks, algae, or eelgrass. For more marine facts, click the SUBSCRIBE button!!