Lone dolphin with spinal deformity travels among a group of sperm whales.

By Linda Poon – National Geographic News

“In 2011, behavioral ecologists Alexander Wilson and Jens Krause of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries in Germany were surprised to discover that a group of sperm whales (Physeter macrocephalus)—animals not usually known for forging bonds with other species—had taken in an adult bottlenose dolphin (Tursiops truncatus).”

“The researchers observed the group in the ocean surrounding the Azores (map)—about 1,000 miles (1,600 kilometers) off the coast of Lisbon, Portugal—for eight days as the dolphin traveled, foraged, and played with both the adult whales and their calves. When the dolphin rubbed its body against the whales, they would sometimes return the gesture.

Among terrestrial animals, cross-species interactions are not uncommon. These mostly temporary alliances are forged for foraging benefits and protection against predators, said Wilson.

They could also be satisfying a desire for the company of other animals, added marine biologist John Francis, vice president for research, conservation, and exploration at the National Geographic Society (the Society owns National Geographic News).

Photographs of dogs nursing tiger cubs, stories of a signing gorilla adopting a pet cat, and videos of a leopard caring for a baby baboon have long circulated the Web and caught national attention.

A Rare Alliance

And although dolphins are known for being sociable animals, Wilson called the alliance between sperm whale and bottlenose dolphin rare, as it has never, to his knowledge, been witnessed before.

This association may have started with something called bow riding, a common behavior among dolphins during which they ride the pressure waves generated by the bow of a ship or, in this case, whales, suggested Francis.

“Hanging around slower creatures to catch a ride might have been the first advantage [of such behavior],” he said, adding that this may have also started out as simply a playful encounter.

Wilson suggested that the dolphin’s peculiar spinal shape made it more likely to initiate an interaction with the large and slow-moving whales. “Perhaps it could not keep up with or was picked on by other members of its dolphin group,” he said in an email.

Default

But the “million-dollar question,” as Wilson puts it, is why the whales accepted the lone dolphin. Among several theories presented in an upcoming paper inAquatic Mammals describing the scientists’ observations, they propose that the dolphin may have been regarded as nonthreatening and that it was accepted by default because of the way adult sperm whales “babysit” their calves.

Sperm whales alternate their dives between group members, always leaving one adult near the surface to watch the juveniles. “What is likely is that the presence of the calves—which cannot dive very deep or for very long—allowed the dolphin to maintain contact with the group,” Wilson said.

Wilson doesn’t believe the dolphin approached the sperm whales for help in protecting itself from predators, since there aren’t many dolphin predators in the waters surrounding the Azores.

But Francis was not so quick to discount the idea. “I don’t buy that there is no predator in the lifelong experience of the whales and dolphins frequenting the Azores,” he said.

He suggested that it could be just as possible that the sperm whales accepted the dolphin for added protection against their own predators, like the killer whale(Orcinus orca), while traveling. “They see killer whales off the Azores, and while they may not be around regularly, it does not take a lot of encounters to make [other] whales defensive,” he said.”

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“Our shy girl, Molly, was found in the intake at the Crystal River Power Plant in Citrus County and brought to the Clearwater Marine Aquarium on July 19, 2006. Upon arrival, Molly was very active and was found to be a good body weight but had a number of injuries. First, her left rear flipper was a stub, which (even today) we are uncertain as to whether or not this flipper sustained an injury and healed on its own, or whether this was a birth defect. In addition, ¾ of her left front flipper was gone, and the left side of her neck had a large, open laceration. Even though these injuries were a few days old, the staff was confident that they were the result of a shark attack.

Molly was kept in shallow water during her first week here at Clearwater Marine Aquarium, but she began to eat squid almost right away, and was scheduled almost immediately to have what remained of her left front flipper amputated. Molly’s procedure was conducted on July 28, 2006 by our former veterinarians, Dr. Cianciolo and Dr. Kirsch. While under anesthesia for over two hours, what remained of Molly’s left front flipper was amputated at her mid humerus and stitched closed. The laceration on the left side of her neck was also treated, cleaned and stitched closed as well. Molly began eating regularly again approximately a week after the surgery. Over the next month, she continued to make progress, and her wounds continued to heal. Once her stitches were removed, she had wound care and cleaning at the site conducted every day. In mid-October 2006, Molly wouldn’t open her eyes and was refusing food even though she was spending most of her time floating at the surface. She had blood drawn for testing, and when all tests could not confirm a specific problem, it was determined from her behavior, lack of appetite, and redness of her eyes that Molly was very sensitive to the amount of chlorine in her pool. Even today, the chlorine level of her pool is set so that it does not exceed 0.3ppm (parts per million).

Molly continued to have her wounds cared for in the months that followed. By February 2007, her skin, her laceration, and her wound from her flipper amputation were almost completely healed, and all of her swelling was gone. The care and cleaning of her wounds continued through the following year, and beginning in 2009, it was determined that she would only need to be pulled once a year for her annual physical. Molly currently resides in “Turtle Cove”, where she shares a pool with her pool mate, Stubby.”