Busty squirrel driving internet nuts may be more sick than sexy, says Alberta ecologist

It's bright-eyed, bushy-tailed and surprisingly big-breasted.

'It's weird. It's definitely strange'

Wildlife biologist Jessica Haines, who researches Canadian red squirrels, has a theory about a viral photo which has sparked a debate around squirrel anatomy. (@boblim1204/Twitter)

It's bright-eyed, bushy-tailed and surprisingly big-breasted.

The internet has gone nuts over an unusually well-endowed squirrel which happens to be a resident of the Inokashira Park Zoo outside of Tokyo.

Since an image of the puzzling creature was shared on Twitter on Oct. 9,  it's been liked more than 142,000 times and shared more than 47,000.

The creature, dubbed the sexy squirrel, has made headlines across Asia and Europe and captured the hearts of animal-lovers, all while puzzling ecologists.

"It's weird. It's definitely strange," said Jessica Haines, an ecologist and assistant professor of biological sciences with MacEwan University in Edmonton.

"It looks like a squirrel that has breasts."

So what exactly is going on with this squirrel?

Haines has a theory.

The squirrel is not sexy, but sick.

Haines has been asked to weigh in more than once. 

A less-than-sexy theory

"A National Geographic reporter called me about this," Haines said in an interview Tuesday with CBC Radio's Edmonton AM.  "They were wondering what was going on with this sexy squirrel.

"My theory is that it could be tumours, which is less sexy than the angle that they were going for."

Haines, who has spent years researching red squirrels in the Yukon, said her theory is based on basic squirrel anatomy.

Unlike humans and some other mammals, the rodents have multiple nipples, Haines said.

"They actually have multiple rows of nipples that start at their chest down toward their abdomen, so if they're lactating you don't just see their two nipples at the top.

"And if you do see a squirrel lactating, it's pretty obvious. They lose a lot of fur around that area because of the young nursing there ... it looks really different from that photo."

Haines' colleague Ben Danzer, an integrative biologist at the University of Michigan, had a different theory.

He thought the squirrel had become really plump from easy access to human food, and its fat deposits were caught at a less-than-photogenic angle.

Either way, Haines wishes the sexy squirrel well, in part because she loves all squirrels.

"Some people are really passionate about squirrels, but I think they're a small portion of the population. 

"I really love them," she said. "I just really respect how they live their lives with so much personality and spunk."