PORTLAND - Dolphins stroke and caress each other almost from birth, using their tail flukes and fins to rub and roll as they pass each other in the warm ocean.
"Sexual interaction in the dolphins is primarily social; it's not just reproductive," says Christine Johnson who studies animal cognition at the University of California in San Diego.
"It plays an extremely important social role in terms of forming relationships, bonding, firming up friendships," Johnson says. "In this respect, it's similar to the role sex sometimes plays in humans."
Speaking last month in Seattle before the annual meeting of the Animal Behavior Society, Johnson said research has revealed a complex social picture, involving long-term alliances, aggression and cooperation, all a veritable soap opera reminiscent of human relationships.
Dolphins in an amorous state provide a graceful aquatic display, like a slow-motion underwater ballet, Johnson says.
"They're just in this mind-altered state," Johnson says. "You can see it in their eyes. It's beautiful to look at."
Even their famous echolocation may be employed. The buzzing sound that helps them locate their prey and other objects through echoes, like sonar, is palpable at close range. When directed at sensitive areas around the face, under the pectoral fins or in the genital area, the gesture elicits a prompt reaction in the receiver, like a child being tickled.
"Sexual behavior with these guys starts from day one," Johnson says. "Moms buzz their babies and teach them how to buzz them back from the start."
Socio-sexual development continues through their adolescent years, sometimes with help from older dolphins, Johnson says. Young males may practice sexual techniques with older females.
"The females will swat them if they do something wrong and will encourage and have sex with them if they do something right," she says.
Johnson also noted inter-species sexual behavior. Researchers have seen spotted dolphins engage sexually with bottlenose dolphins, with partners often both males. They speculate the dolphins may be enacting a dominance hierarchy or affirming some kind of cooperative alliance.
No one can positively explain such alliances, but dolphins are known for affinitive behavior.
Social alliances are critical in the dolphins' world. They have no nest, no burrow, nowhere to hide from predators. Their need to stick together was likely a powerful force in their evolutionary past, scientists say.
Perhaps it's not surprising, then, that dolphins also employ socio-sexual techniques on human observers. More than one visitor has received a bit of a shock when a friendly dolphin has approached and sent a flurry of echolocating vibrations into the groin.
"What they seem to be doing is figuring out what sex you are," says Johnson, who has observed that male dolphins seem to pick out the women divers, while the females focus on the men.
"They have this wonderful experience of having the dolphins rubbing up against them and carrying them around, and they come out going, `Oh, my God!' "