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Sea Slugs

The striped nudibranch has irregular stripes and long growths on the back. (The Southeastern Regional Taxonomic Center, South Carolina Department of Natural Resources)
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The striped nudibranch has irregular stripes and long growths on the back. (The Southeastern Regional Taxonomic Center, South Carolina Department of Natural Resources)

Sea slugs are soft-bodied, shell-less mollusks that live throughout the Chesapeake Bay.

Eight species of sea slugs can be found in the Chesapeake Bay:

  • Cross-bearer sea slug, Hermaea cruciata
  • Dusky sea slug, Stiliger fuscatus
  • Emerald sea slug, Elysia chlorotica
  • Kitty-cat sea slug, Elysia catula
  • Limpet nudibranch, Doridella obscura
  • Ridged-back nudibranch, Polycerella conyma
  • Rough-back nudibranch, Dorisverrucosa
  • Striped nudibranch, Cratena pilata

The first four species are sacoglossans, which are sea slugs that feed on plants. The last four are nudibranchs, which are carnivorous sea slugs.

Appearance:

  • Soft bodies that look similar to garden slugs
  • Vary in color. Sacoglossans are often uniformly green. Nudibranchs blend in with the surface they are on.
  • Tentacles on the head
  • Sensory tentacles called rhinophores toward the back of the body
  • Various gills, tubercles and club-shaped growths on the top part of the body
  • Vary in size from one-eighth of an inch to 1.5 inches long

Habitat:

  • Live in a variety of mostly shallow-water habitats, including reefs, pilings, buoys, marshes, creeks and bay grass meadows

Range:

  • Different species are found in different parts of the Chesapeake Bay
  • For example, emerald sea slugs are only found in Maryland waters. Kitty-cat sea slugs and rough-back nudibranchs live in the saltier waters of the lower Bay.

Feeding:

  • Sea slugs are categorized depending on their diet
  • Sacoglossans are herbivores. They suck out and feed on the internal contents of algae.

  • Nudibranchs are carnivores. They feed on tiny animals such as hydroids. Each nudibranch family tends to eat one or two particular types of food.

Predators:

  • Because they lack shells, nudibranchs rely on bright coloration and strong scent to avoid predators
  • Some nudibranch species can eat the stinging cells of jellyfish and store them in their cerata. These “adopted” cells become part of the sea slug’s defense system.

Reproduction and Life Cycle:

  • Sea slugs have both male and female sex organs. They are able to mate with any individual of the same species.
  • Eggs may take 5-50 days to develop into free-swimming larvae

Other Facts:

  • If taken out of water, sea slugs turn into shapeless lumps. To see their true shape, keep them in water.
  • Sea slugs are mollusks. They shed their shells before they hatch or when they are larvae.

Sources and Additional Information:




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