Bilateral symmetry in crayfish behavioral reactions.

The crayfish, Procambarus cubensis, placed in the central area of a plus-maze preferred to go forward in about 50% of trials; they chose the right or left arm in 20.7 and 18.9% of the trials, respectively. In a T-maze, the difference between right and left directions was also insignificant. When exploring a plus-maze, the crayfish turned to 180 degrees at the end of the arms, then turned to 90 degrees going to the next arm. The mean difference between the right and left U-turns, and the right and left turns was insignificant though some animals demonstrated a left or right preference. There was a strong correlation between the direction of U-turns and following turns ensuring the clockwise or anti-clockwise movements of the crayfish. Also we examined a possible preference of the right or left claw in the feeding behavior of the crayfish. The crayfish caught a small bloodworm given from above equally with the right or left claw. The crayfish conditioned to take a bloodworm with a claw did not demonstrate any stable preference of left or right claw in the course of the experiments. The question of bilateral asymmetries within the decapod crustaceans is discussed.