The hooded seal slug also known as the Lions Mane Nudibranch is part of the family Tethydidae. The body of this unusual predatory seal slug is usually colorless sometimes it has a pale yellow or green coloring with an opaque brown expanded oral hood. This hood has sensory tentacles which the hooded seal slug is able to open and throw forward to catch its food. They attach themselves to kelp and eelgrass, and the hood works like a net catching their food. When the ventricles that are attached to the head connect with a small animal the fringing tentacles will overlap holding the prey in place before placing the whole animal into its mouth. These seal slugs prey on small crustaceans, more locks, amphipods, copepods, small jellyfish, mysids, and some small fish. When they are removed from the water they have a sweet fruity odor which is often referred to as the bouquet when they are grouped together.
This particular seal slug is usually found along the West Coast of North America and can be found from Alaska to Baja California. The lifespan of the hooded seal slug is usually about a year. They lay their eggs which attached to kelp and eelgrass in long yellow or cream – colored ribbons after the eggs are laid sea slug dies.
The seal slug also has predators which would include sea stars kelp crabs and larger fish. The hooded seal slug when endangered can shed its cerata, which will float away from them often distracting their predator allowing the slug to escape. Slugs are capable of swimming and often travel long distances through open waters they swim upside down inside to side with a thrashing motion using a very complex series of movement that have been studied extensively and though it may look awkward they are able to swim efficiently.
Because of its unique and unusual appearance while in the water is clearly identifiable, however if he could stranded on the beach is often mistaken for a jelly because it resembles a gelatin like blob. The maximum length of the hooded sea slug is about 4 inches. These unusual creatures may be found in swarms and even though there often found in low water areas they have been found in waters as deep as 115 feet. The Leonina was named accordingly because of its African lion mane appearance. These intriguing creatures are well worth stopping to watch while visiting an area with a well developed kelp bed.