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The California Sea Hare
The Sea Slug or Sea Hare: A Laguna Beach Local
This is probably the world's first fan page devoted to the California sea hare. No, seriously. When I looked up A. californica online after finding a tidepool full of them, I discovered some fascinating facts about this unassuming animal. Not only does it switch sexes every other day during at least part of its life cycle; it's played an important role in Nobel Prize-winning research in neuroscience!
Not bad for a critter that doesn't even have a spinal cord.
On this page I'll share photos, videos, and basic information about the California Sea Hare, a large sluglike mollusk found snuffling about the tidepools off the coast of California. For beachcombers, tidepoolers and nature lovers, I hope I can give you some appreciation for an animal that doesn't have quite the star power of a clownfish (of Finding Nemo fame) or humpbacked whale. For marine biology students looking for more in-depth scientific information than my Sea Hare factsheet covers, check my links section below: I may not have the level of expertise you're looking for, but I've found a few sites that do!
Video: California Sea Hares - Tidepools at Laguna Beach in Orange County, CA
Sea hare video clips taken by me and my mother (Ann Brundige), 02.27.09.
They're oddly cute, aren't they? Although the hermit crab caught in the slow-motion hit-and-run in the first clip might dispute me, if it had higher brain functions.
All About California Sea Hares - Scientific Name: Aplysia californica
There's dozens of species of sea hares, sluglike marine animals found around the world. The California Sea Hare is a brown or reddish spotted species found all along the coast of California down into Baja.
- Names: California Sea Hare, California Sea Slug, Aplysia californica
- Size: Varies. A foot (30 cm) is typical for full-sized adults when stretched out. Those pictured here were closer to 5 to 8 inches.
- Weight: According to this Aplysia Californica size chart, foot-long California Sea Hares are typically around 100 grams; the ones I saw were closer to 20 grams.
- Diet: Unlike some sea hare species, Califonia Sea Hares are vegetarians! They eat Coralline Algae (brown or red algae), soft frilly stuff found in rocky tidepools during low tides. In other words, they fill the same role as aquarium fish used to clean up algae and keep tanks scum-free.
- Color: Dark brown to reddish-brown, sometimes with a yellowish or pink cast, depending on the color of their food. Adults are mottled and well-camouflaged. Young juveniles are pinkish-orange and don't show mottling.
- Anatomy: They're gastropods, from the Greek for "stomach-foot," which describes most of their body. They have a small bit of leathery shell inside, protecting some of their organs. They have a sucker-like mouth and a pair of small black eyes on the top of their head. But they do most of their tasting/smelling/sensing using their "rabbit ears," the pair of short tentacles behind their eyes that gives sea hares their common name. These tentacles are called "rhinophores." Sea hares use them not only to detect food but also enemies, their surroundings, and other sea hares. (They also have two more tentacle-like "toes" at the leading edge of their foot, on either side of the mouth, which can look like rabbit ears from above).
- Lifespan: Usually a year. Here's a diagram with videos showing you the life cycle of sea hares at different ages.
- Reproduction: California Sea Hares are hermaphrodites, meaning they have both male and female parts -- in fact they alternate being male or female on different days! Eggs hatch after 8 or 9 days into microscopic larva, which gradually grow into full-sized slugs, dining on other kinds of red algae as juveniles.
- Habitat: Shallow tidepools with red algae in the "Low Tide Zone," only exposed during the lowest tides each month. In Orange County, I've noticed bright purple sea urchins during these especially low tides, so if you can see them, start hunting for sea hares in shallow pools with pinkish red algae. You'll also see blue mussels, hermit crabs, and sea anemones in the area (although these also live higher up, so they are not reliable indicators of sea slug habitat).
- Fun Facts: This kind of animal has been called "sea hare" since antiquity, since some European species are markedly rabbit-shaped. The purple ink of one species was used by ancient scholars in Jerusalem to write sacred texts-- maybe even the Old Testament!
Going Tidepooling? Keep This in Mind...
Be gentle, if you come across a sea hare. They have no bones and tear easily. You can pet them lightly, but don't prod, stab, squash, or pull on them. (They're quite soft to the touch, like wet velvet). They're not poisonous, and they won't do anything worse than squirt ink if alarmed.
California Sea Hares: Nobel Prize Winners!
Helping Neuroscientists for Over Fifty Years
The nervous system is the "wiring" that makes our bodies work. It includes our brains. It just so happens that California Sea Hares have very simple nervous systems and very large neurons (nerve cells), making them perfect subjects for studying neurobiology!
A lot of what scientists now know about the human nervous system, neurons, reflexes, memory, and even complicated behavior like learning grew out of studies of Aplysia californica.
"In 2000, Dr. Eric Kandel won the Nobel Prize in Physiology or Medicine for his research in how neurons are able to form and store memories. For this award-winning research, he used Aplysia from Rosenstiel School's National Resource for Aplysia along with neurons from mice. Other studies of Aplysia have led to drugs now in clinical trial aimed at reversing memory loss in patients with degenerative mental diseases."
In other words, drugs currently being tested to reverse Parkinson's Disease and Alzheimer's have been developed thanks to the humble California Sea Hare!
California Sea Hare Links - My Bibliography For This Page
I'm not a marine biologist. In fact, when I saw these animals in tidepools at Laguna Beach, I didn't know anything about them except that they were sea hares! I Googled "sea hare" and studied a lot of photographs and descriptions on expert websites until I was sure I'd identified my slug. (A pity there's not much of a market for a Roger Tory Peterson Guide to Marine Invertebrates.)
Here's the websites where I found all my information.
- "Aplysia californica" on the Sea Slug Forum
The Sea Slug Forum, moderated by marine biologist Bill Rudman at the Australian Museum, is surprisingly fascinating, with lots of information and great pictures. Here's questions and answers submitted to Bill on the California Sea Hare.
- Tidepool Ecology: Laguna Ocean Foundation
All about the tidepools of Laguna Beach, with the types of animals and plants typically found there.
- Tales from Our Tidepools, Treasures Beneath the Sea
A lecture given by marine biologist Genny Anderson at UC Santa Barbara. Great introduction to tidepooling on the California coast. Near the end of the "Treasures Beneath the Sea" section are two amazing photos of California Sea Hares inking.
- The Rosenstiel School: Aplysia Facility
National Institute of Health facility where California Sea Hares are bred and used to study neurological diseases like Alzheimer's and Parkinson's. This incredibly detailed site tells you all about their biology, how to care for (and order!) them, an
California Sea Hare, Laguna Beach
More Sea Hare Videos
Here's a couple more videos of sea hares by people with better cameras than mine!
© 2009 Ellen Brundige