Sea Hare

Aplysia californica





The Sea Hare is a marine invertebrate that can be as long as 40 cm and weigh up to 5 lbs (1).  While many of these organisms are seen with a purple/red pigmentation, the color remains dependent upon the color of algae that they eat (1).  The Sea Hare can be found within coastal waters with thick vegetation since the primary food is kelp (1). The marine snail is an important model organism used to study neurobiology (2).  More specifically, this mollusk  is used to study the neuroscience regarding learning and memory because the animal has large and few neurons (1,3).  From this, comes the ability to identify specific nerve cells responsible for certain behaviors (1).  One adaptation that researchers believe to be a a defense mechanism against predators is the release of reddish ink from a gland within the mantle (1).

(1) California Brown Sea Hare. (2018).  Retrieved from

(2) Kempsell, A.T., Fieber, L.A. (2015).  Aging in Sensory and Motor Neurons Results in Learning Failure in Aplysia californica.  PLOS ONE, 10(5), e0127056. DOI: 10.1371/journal.pone.0127056

(3) Sun, Y., Monje, F.J., Pollak, D.D., Lubec, G. (2011). A first partial Aplysia californica proteome. ProQuest, 41(4), 955-968. DOI:10.1007/s00726-010-0795-9

(Photographs) Peter J. Bryant, University of California, Irvine


  • Rocky Shore/ Intertidal Zone