What's the size of a large house cat, has a long rat-like tail, sharp fangs, and a face like a psychotic rodent? It's the opossum, of course, the weirdest and hardiest creature in Toronto's urban menagerie.

Sightings are rare, but the city is home to a small population of the strange looking marsupials. When an opossum appears, the reaction is often fear and confusion.

Michelle Mendlowitz is a ceramic artist who works out of a studio on the Danforth near Woodbine. One evening, close to midnight, what looked like a large, white rat came running in through her open door. "I was glazing and I had the door open because it was hot," she says. "I saw something run in through the corner of my eye, and I was like, 'what was that?'"

"I walked outside and there was a couple standing across the street and they were just pointing. I was like, 'err... was that a raccoon?' and they were like 'nope.'

'Oh, was it a cat?'

'Nope'

'What is it?'

'I have no idea.'"

The creature, perhaps frightened by the noise of the street, hid somewhere in the building, but no-one could find it. Another witness identified the mystery creature as an opossum (or possum, if you like.) "I tried banging and then I looked a little bit online and it said that if you scare it it plays dead and makes itself smell like its dead, so I was like 'maybe that's not a good plan.'"

David Sugarman, a wildlife expert from the Ontario Science Centre, says Mendlowitz read correctly about the opossum's propensity to fein death.

"It is real and it's not planned, it's not like they are playing dead," he says. "First of all they will do other things to try to scare off a potential threat like hissing, and bearing their teeth and stuff, trying to look a bit scary. But if that fails they actually faint. It's actually losing consciousness."

"It can last up to four hours, but it's accompanied by some interesting other behaviours. Their eyes are open, their mouths are slack, they're drooling. They release a bad smell from their anal glands."

Yuck.

The opossum's bizarre physiology includes forked penises and twin uteruses, unusually large jaws and teeth, and a formidable immune system capable of staving off bites from venomous snakes like cottonmouths and rattlesnakes. Botulism bacteria and ricin are also ineffective, Sugarman says.

The immunity to poisonous snakes hints at the opossum's origins in the southern parts of the United States and into Mexico. Southern Ontario and parts of British Columbia near the U.S. border are at the extreme north of the marsupial's range, making them a relative rarity in Toronto.

Mendlowitz's trapped opossum was eventually caught in a live cage and released in a nearby ravine.

The reason they thrive in the city, Sugarman says, is their ability to eat just about anything. "They'll live wherever there's food and being super omnivores like raccoons they can live off almost any kind of food: dead animals, rotting fruit ... if there's a plentiful supply of that stuff then they will be able to live." He thinks mild winters and abundant food scraps will allow the population to grow.

"If things continue the way they do, we may gradually see them becoming more common."

Chris Bateman is a staff writer at blogTO. Follow him on Twitter at @chrisbateman.

Image: Tony Alter/Creative Commons