The gorillas perform basically three different kinds of splashing: one- and two-handed splashes, and a body splash.
The body splash is much like a "cannonball," in which people run and jump into a swimming pool. The gorillas, however, don't tuck their legs under them when they jump, as people do.
In one- and two-handed splashes, the animals raise one or both arms and strike the surface of the water with their palms open and slightly angled.
The splashing behavior was seen most often in single adult males who were not with a group of their own (relative to their number in the population). These single, adult males were also the target of most splashing displays.
Young gorillas sometimes play in the water, but the splashing conduct of the adult gorillas was limited to males. Adult females never engaged in splashing.
The use of water as a tool for communication is thought to be extremely rare among land-based mammals. The only other evidence of splashing behavior something like that of the gorillas in the Congo came from studies of a chimpanzee community in Tanzania. The chimps were found to throw rocks into streams apparently also as an act of intimidation.
The discovery that western lowland gorillas use water to communicate suggests that they are able to adapt to their environment to achieve their goalsin this case, to intimidate potential rivals.
An act of intimidation that almost all wild gorillas engage in is charging toward a rival but veering away at the last moment, then smacking their palms down on the ground with a thump.
The researchers say that while all gorillas exhibit the charging and ground-slap behavior, that act and the splashing behavior are different enough to suggest that the western lowland gorillas have adapted to an aquatic environment.
In a paper in the July 16 issue of Nature describing their splashing study, the scientists said: "We anticipate that gorillas, maligned as cognitively poor cousins to the other great apes, will emerge from further bai studies as adaptable, innovative, and intelligent creatures that exploit a complex environment."
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