134 • Alternatives to Animal Use in Research, Testing, and Education 
remains a major logistical obstacle. The develop- 
ment of a dead or artificial food ration is currently 
a high priority in octopus culture (88). The same 
highly developed nervous system that makes the 
octopus and squid desirable replacements for ver- 
tebrates may cause some ethical objections to use 
of these invertebrates. In addition, their adapta- 
tion to a completely aquatic existence would also 
make tenuous any extrapolations to the behavior 
of terrestrial mammals. 
Starfish and sea urchins exhibit habituation— 
the waning of a response to stimuli, as a result of 
repeated elicitation of that response— and they can 
learn escape behaviors in response to a cue paired 
with aversive stimulation (46). 
Earthworms exhibit habituation (45), can learn 
to associate light with a food reward (66), and can 
learn to travel a maze to receive darkness and mois- 
ture as reinforcing stimuli (85). Flatworms are also 
of considerable interest, since they represent a 
bilateral body form, as do mammals. Flatworms 
exhibit a concentration of nervous tissue and sen- 
sory organs in the anterior, or head, portion of 
their bodies, and they have refined internal or- 
gan systems (47). Flatworms exhibit habituation, 
can be conditioned to avoid a light after it has been 
paired with shock, and can learn to approach an 
area for food reward. There are also claims that 
such learned events are remembered after these 
worms undergo regeneration, and that learning 
can be transferred from one animal to another 
by cannibalism (reviewed in ref. 47). 
Insects are valuable behavioral models in com- 
munication, navigation, learning and memory, and 
behavioral genetics. 
Octopus ( Octopus bimaculoides) Cultured From the Egg in the Laboratory 
Photo credit: Lab. Anim. Sci. 35(1):34. Copyright 1985, American Association for Laboratory Animal Science 
