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article imageSperm whales adopt dolphin with spinal deformity

By Abigail Prendergast     Jan 20, 2013 in Science
A group of sperm whales took in a deformed dolphin when observed by biologists in 2011. While there is a good amount of evidence as to why the dolphin was affectionate toward the whales, it is unclear why the cetaceans took it in.
Animal loyalty to another species is by no means a new concept; from a mother tiger nurturing piglets, to a hippopotamus becoming close friends with a tortoise, every Sunday, it has always been news that touches hearts.
According to Science NOW, a more interesting type of inter-species kindness has taken place. A group of sperm whales - which are known as "fierce squid hunters" with a gentle side - have by chance discovered a grown bottlenose dolphin with a spinal deformity and took it in, "at least temporally," researchers found.
While many animals in nature can and often do form bonds with other genus types, they generally only last fairly briefly, though long enough to offer more "protection from predators and more effective foraging."
However, there have been a few reported cases in which creatures forge long term bonds with other species. Such as the aforementioned examples and also a case in which Koko, a singing gorilla, had her own pet cat.
As far as ocean-dwelling mammals are concerned, "dolphins are perhaps the most gregarious," Science NOW writes. While they can be seen frolicking around their aquatic back yards and getting friendly with other creatures. Conversely, sperm whales have never been "reported reported cozying up to another species."
With that in mind, when behavioral ecologists Alexander Wilson and Jens Krause of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries in Berlin were not anticipating to see a "mix-species" mingling of any kind as they began their observation of sperm whales about 20 kilometers off of Azores' Pico island in 2011. When they got to their destination, they couldn't help but notice several white whale calves in addition to an adult bottlenose dolphin.
For the next eight days, the duo "observed the dolphin six more times while it nuzzled and rubbed members of the group," says Science NOW.
At the very least, the sperm whales tolerated the dolphin's affection, and even returned the favor every so often.
"It really looked like they had accepted the dolphin for whatever reason," said Wilson. "They were being very sociable."
The research team was just about positive it was the same dolphin each time due to "a rare spinal curvature that gave its back half an 'S' shape."
It was this deformity, which was probably a birth defect, that was potentially "the key to understanding its attachment to the sperm whale group," considering the waters of Azores rarely see predators, so protection wasn't seen as an issue.
It is thought that the dolphin's spinal malformation (it seemed completely healthy otherwise) left it in a position where "it couldn't keep up with the other dolphins or had a low social status."
"Sometimes some individuals can be picked on," Wilson pointed out. "It might be that this individual didn't fit in, so to speak, with its original group."
Since the whales were more lethargic swimmers, the dolphin had a much easier time keeping up with them.
Even so, it isn't quite as clear why the whales took in the dolphin or what they hoped to gain by doing so. While this study shows that the cetaceans do in fact have the "capacity for these types of relationships," it also implies that they normally benefit from them in some way.
In this case though, their is no real advantage for the whales, at least not as far as researchers can see. Cetacean ecologist Mónica Almeida e Silva of the University of the Azores in Portugal, stated that sperm whales have no reason to like dolphins, let alone take one in. She said she has even witnessed the latter species harass both whales and their young.
"Why would sperm whales accept this animal in their group?" she inquired. "It's really puzzling to me."
At the end of the day, it is, in fact, pointless to read too far into what may seem as pity on the part of the whales, said behavioral biologist Luke Rendell of the University of St. Andrews in the United Kingdom. Since the study was not only surrounding a rare occurrence, but was brief too, so drawing proper conclusions is tricky. For all we know, the whales could simply be entertained by the dolphin's company in some sort of way, he said.
More about Dolphin, Sperm whale, spinal deformity