Preference for background color of the Xenopus laevis tadpole.

The background color preferences of three age groups of Xenopus laevis tadpoles (young-stages tadpoles [stages 44-46], premetamorphic tadpoles [stages 54-56], and metamorphic tadpoles [stages 58-60]) were examined. Young tadpoles selected a white background, metamorphic tadpoles preferred a black background, and premetamorphic tadpoles selected a white or black background consistent with the background black or white of the test box on which they previously were conditioned. If premetamorphic tadpoles were conditioned in the checkerboard-pattern (white and black) box or white box which was placed a small black square at the center of the box, they preferred to stay in the white area just after transfer to the test box, then shifted their preference for background color to black strongly. Premetamorphic tadpoles conditioned on a white background lost this preference if kept in the dark for 12 hours. Blinding of premetamorphic tadpoles by severance of the optic nerves resulted in loss of preference for a specific background matching the white or black background to which they had been adapted while sighted. Given a choice 3 days postblinding, they tended to congregate on a white background. Injection of MSH into premetamorphic tadpoles conditioned to white shifted their preference to black. In contrast, injection of melatonin stimulated black adapted tadpoles to select a white background. Young frogs showed a preference for a black background.