Sea Slugs' Gigantic Neurons

  • By Anna Rothschild
  • Posted 07.30.15
  • NOVA

The California brown sea hare has gigantic neurons. It also has a very strange way of reproducing. Find out more in this episode of Gross Science.

Running Time: 01:49


Sea Slugs' Gigantic Neurons

Posted: July 30, 2015

One of the kinkiest animals on the planet might be the California brown sea hare—a sea slug with gigantic...neurons.

I’m Anna Rothschild, and this is Gross Science.

The California brown sea hare, also called Aplysia californica, is a type of sea slug that lives off the coast of California and in parts of northern Mexico. It eats algae that makes it pretty toxic, so it doesn’t have a ton of natural predators. However, if another animal does happen to spook it, the sea hare squirts sticky, bright purple ink at its assailant (which personally is a defense mechanism that I would love to have.)

But these guys do more than eat algae and squirt ink. They also have quite edgy sex. Aplysia are hermaphrodites and have both male and female reproductive organs. When they mate, they sometimes form long “mating chains” of up to 20 individuals. The sea hare at the front of the chain acts as a female, and the one at the back acts as a male. But all the slugs in the middle act as both males and females—they inseminate the partner in front of them while receiving sperm from the one behind. It’s really quite a time-saver if you think about it.

Anyway, scientists get pretty excited about Aplysia, not so much for their mating habits, but more for their brains. This sea hare’s nervous system is made up of a small number of very large neurons, making Aplysia californica an excellent neuroscience test subject. In fact, the scientist Eric Kandel used Aplysia to study how memories are stored. And thanks to that kinky little sea slug, he won a Nobel Prize for his work.




Host, Writer, Animator, Editor
Anna Rothschild
DP, Sound
Rachel Becker
Many Thanks to Dr. Tom Capo.
It Is Nice To Walk With You
Music Provided by APM


Inking Aplysia
©Genevieve Anderson
Aplysia punctata mating
©Paul Naylor


(used with permission from author)
Squeak Pack/squeak_10
Produced by WGBH for PBS Digital Studios


(main image: Aplysia Mating)
©WGBH Educational Foundation 2015


Want more info?

NIH/University of Miami National Resource for Aplysia:

A brief autobiography of Eric R. Kandel:

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