Aplysia gill and siphon withdrawal reflex

The Aplysia gill and siphon withdrawal reflex (GSWR) is an involuntary, defensive reflex of the sea slug Aplysia that causes its delicate siphon and gill to be retracted when the animal is disturbed. The reflex is mediated by a siphon LE mechanosensory neuron and a gill or siphon motor neuron (L7 or LFS).

It is valuable in neuroscience since it can undergo a variety of learning regimens, including habituation, sensitization, and conditioning, despite the simplicity of the underlying neural circuitry.

Eric Kandel, recipient of the Nobel Prize in Physiology or Medicine in 2000 for his work with Aplysia, was involved in pioneering research into this reflex in the 1960s and 1970s.