Giant Black Sea Hare

3. Sea hares are hermaphroditic, each animal is both male and female.

4. To facilitate mating, sea hares form a circle and then each animal inseminates the one in front. This group sex event has been dubbed a “Roman circle.”

5. A single sea hare can lay up to 500 million eggs during one breeding season.

6. Sea hares produce purple ink as a defense mechanism; this ink was used by Native Americans to dye clothing.

7. Biomedical researchers use the sea hare’s very simple nervous system as a model for other more complicated species. The neurophysiology of sea hares is being used in cancer research and sea hare sex hormones are providing clues to understanding more about human development. 

http://oceanwildthings.com/2011/05/7-cool-sea-hare-facts/

Although this Pacific gastropod is interesting in its own right, the slug is of greatest importance to humankind as a research animal (like the regenerating axolotl).  Aplysia has only 20,000 neuron cells–as opposed to a human brain which contains between ten and a hundred billion–and the slug’s neurons are extremely large.  This allows neuroscientists to easily observe and assess physiological and molecular changes which take place in the cells when the slug learns something.  Aplysia research is thus at the cutting edge of neuroscience.  Nearly everything we know about the molecular basis of memory and learning started out as research with the humble gastropod.

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