International Journal of Comparative Psychology

Captive belugas ( Delphinapterus leucas ) often spit water as object play. One female beluga spit water at a ball to obtain it for play. We examined whether or not this behavior could be considered a tool-use behavior. When the ball was placed 10 cm from the poolside, the beluga poked the ball with her rostrum, while she often spit water at the ball at 50cm. This water-spitting behavior became more predominantly when the ball was placed at 30 cm or farther, corresponding to the maximum distance she could reach, suggesting her understanding of the cause-effect relationship. Next, the two balls were placed at 30 cm and 60 cm, and one was placed inside the rings, so it would not be easy to move it out by water-spitting. When the closer ball was placed in the ring, she tried to spit water at the ball farther away but without the ring, suggesting an understanding of efficiency in tool use. Furthermore, during this study, the beluga showed the behavior of throwing the ball obtained by spitting water at another one with her mouth. This generalization may be based on the causal understanding established through water-spitting.