Summary ⁶

The California sea slug or California sea hare, scientific name Aplysia californica, is a species of sea slug, specifically a sea hare, a marine opisthobranch gastropod mollusk in the family Aplysiidae, the sea hares.

Physical description ⁷

The California Black Sea Hare is probably the world's largest gastropod. It can weigh up to 35 pounds! It is typically about 16" long (41 cm) and 8" (20 cm) wide and high. Plump and soft, it has winglike flaps around the top of its head on both sides. Aplysia californica can be reddish, brownish, or greenish, spotted with white or dark circles and lines. The colors reflect the type and color of algae they are prone to eat. They feed with a pair of jaws and a grasping radula. On top of their head, two pairs of antennae are found: one low near the mouth and another behind the eyes. A foot used to help in locomotion extends a little farther than the entire length of the animal. The anterior tentacles are much larger and ear-like (thus its common name- the sea hare) than the second pair which are used more for smelling. They also possess winglike flaps called parapodia that are used for swimming. The mantle folds over and covers a thin, transparent, and flexible shell. In its wall are unicellular glands that secrete a purple dye when the animal is handled. The sea hare does possess a developed nervous and digestive system. In its digestive tract there is an alimentary canal in front of the stomach that ends in a crop lined with horny plates for better mastication before digestion of food.

Food habits ⁸

Aplysia californica are herbivorous and feed on a variety of algae and eelgrass. Their pair of jaws and broad rasp-like radula help crop the seaweed they eat. The color of the particular animal matches the color of the algae or vegetation they feed on the most.

Reproduction ⁹

A. californica is hermaphroditic. Armed with a single aperture and duct for the sperm and ova, this species reproduces sexually. They travel to deeper waters to spawn around spring time. Once fertilized, their eggs are laid down in pink, gelatin-like stringed sacs coiled around seaweed or rocks.

Economic importance for humans: positive ¹⁰

Aplysia californica are used extensively in studies of behavior, reproduction, and development in such fields as chemistry, biology, and psychology.

Habitat ¹¹

Aplysia californica are marine animals that inhabit coastal regions thick with vegetation. This particular species ranges from Northern California to Baja California. They can usually be found crawling around the seaweed they use as a source of food. The younger generation live in the deeper waters where they are born while the adult generation lives in shallow, sheltered places with low tide.

Sources and Credits

1. (c) Kevin, some rights reserved (CC BY-ND), http://www.flickr.com/photos/42857504@N05/3952895728/
2. (c) Ken-ichi Ueda, some rights reserved (CC BY), http://www.flickr.com/photos/18024068@N00/4156879719
3. (c) NOAA Photo Library, some rights reserved (CC BY), http://www.flickr.com/photos/noaaphotolib/5077885029/
4. (c) Malingering, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/malingering/2208286990/
5. (c) Richard Ling, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/rling/5101120099/
6. Adapted by Ken-ichi Ueda from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Aplysia_californica
7. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18633622
8. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18633624
9. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18633623
10. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18633625
11. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18633621

More Info

• iNat taxon page
• Animal Diversity Web
• Biodiversity Heritage Library
• BOLD Systems BIN search
• CalPhotos
• Global Biodiversity Information Facility (GBIF)
• NatureServe Explorer 2.0
• SeaLifeBase
• World Register of Marine Species

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