Sea Slugs

Sea slugs are soft-bodied, shell-less mollusks with:

• Oral tentacles on the head.
• Sensory tentacles called rhinophores toward the back of the body.
• Various gills, tubercles and club-shaped growths called cerata on the top of the body.
• Look like graceful, delicately colored garden slugs.
• Vary in size from one-eighth of an inch to about 1.5 inches long.
• Blend in with the color of the surface they are on.

Where do sea slugs live?

Sea slugs can be found in various parts of the Bay, on and around:

• Reefs
• Pilings
• Buoys
• Hydroids
• Bay grass meadows

What do sea slugs eat?

Sea slugs are divided into two basic types, depending on their diet:

• Herbivorous sacoglossans feed on algae and other plants.
• Carnivorous nudibranchs feed on animals, such as hydroids or jellyfish polyps. Each family of nudibranchs tends to eat one or two particular types of food.

How do sea slugs reproduce?

Sea slugs are hermaphrodites, meaning that each has both male and female sex organs. They are able to mate with any individual of the same species.

• Eggs are fertilized and spirals of egg cases are laid.
• Eggs may take five to 50 days to develop into the first larval form, the free-swimming veliger phase.

Other facts about sea slugs:

• Eight species of sea slugs—four sacoglossans and four nudibranchs—are found in the Bay.
• Because they lack shells, nudibranchs rely on bright coloration and strong scent to avoid predation. Some species can eat the stinging cells of jellyfish and store them in their cerata. These “adopted” cells become part of the nudibranch's defense system.
• If taken out of water, sea slugs will turn into shapeless lumps. They should be kept in water to view their true shape.