Abstract:
Visual stimuli and socialization influence exploratory behaviour in crayfish.
The predominant components of spontaneous exploratory behaviour were determined by
observing the activity of solitary adult crayfish (Procambarus clarkii) in a glass aquarium
containing fresh water and no objects. Five distinct behaviours were observed: rearing up
(climbing on the wall), turning around, cornering (facing the comer), backward walking, and
crossing (crossing the midline of the aquarium). The frequency of rearing up, cornering and
turning around decreased when reflection from the glass wall was blocked with black
cardboard, black paint or non-reflective transparent plastic. In a tank containing mirrors on
one side and non-reflective plastic on the other, crayfish cornered, reared up, and turned
around more in front of the mirrors. Socialization was necessary for crayfish to respond to
the reflection. Crayfish that were housed in pairs for two weeks exhibited more rearing up,
turning around and cornering in front of the mirrors than in the non-reflective side. Crayfish
isolated for two weeks did not show these differences. Socialized crayfish also exhibited
more rearing up, turning around and cornering than did isolated crayfish. Thus, crayfish
respond to visual stimuli provided by a glass tank, but the responds depends on socialization.
