© Photograph courtesy Alexander Wilson and Aquatic MammalsA bottlenose dolphin, with an S-shaped spinal deformity, is seen here rubbing against a sperm whale.
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.
