10 Facts About Aplysia

Splitting Hares

Aplysia were given the common name ‘sea hares’ by the Ancient Greeks because of their supposed resemblance to the European hare; the "ears" are certainly reminiscent of rabbits! Technically, those are not ears, but rather sensory organs on the top of its head, called rhinophores.

California-Style

Aplysia californica are marine animals that live in coastal regions thick with vegetation. Because they are native to the geographic area from northern California to Baja California, their species name is californica. The younger generation lives in the deeper waters of the Pacific where they are born, while the adults live in shallow, sheltered places with low tide.

You Are What You Eat

You can find Aplysia of a variety of colors: white, green, black, or even our favorite — reddish purple. The color of an individual is determined by the color of the algae or other plant material on which it feeds, but in general they are shades of red, brown, or green.

Seeing Purple

If it feels threatened, Aplysia can release a jet of purple ink, which creates a smoke screen of protection. The ink is an irritant to many predators, so they quickly back off. In ancient times people in Jerusalem have used this ink to write sacred texts.

Nerve Central

Aplysia californica are often studied by neurobiologists because of the simplicity of their nervous system. An animal's entire nervous system contains about 20,000 neurons, making it easier to study than that of higher animals like human beings, which can have more than 100 billion neurons (in an adult brain).

Gigantic neurons

The cell body of one neuron (brain cell) in this animal can measure up to 1 mm in diameter, which makes it relatively easy to study specific neural changes that constitute learning and memory. Scientists are currently studying Aplysia to discover a cure for debilitating brain diseases like Alzheimer's and Parkinson's.

A Weighty Subject

The California Black Sea Hare are among the world's largest gastropods, from the phylum molluska. They can weigh up to 35 pounds (the weight of about 2 big bowling balls!) and have been known to grow up to 35 inches long.

Reflex Redux

An important behavior of Aplysia, often exploited for neurophysiological studies, is siphon withdrawal, a simple reflex that occurs when the animal is disturbed. This behavior consists of the animal pulling its siphon back into the mantle cavity and is a reflex that can be studied through use of behaviour modification techniques.

Hermaphro ... huh?

Aplysia are hermaphroditic. That means that one individual animal has sex organs of both sexes in a single animal. The eggs are fertilized from a sperm storage chamber called the seminal receptacle, just before they are laid.

A Nobel Cause

Dr. Eric Kandel, a professor at Columbia University, was instrumental in founding our facility. In 2000 he was awarded with the Nobel Prize in Physiology or Medicine for his work using Aplysia californica from our facility to demonstrate fundamental ways in which nerve cells alter their responsiveness to chemical signals to produce a coordinated change in behavior.