Why Are Opossums Awesome?

They eat trash and they look a little freaky, but the North American opossum is a smart, clean, disease-fighting, and all-around fascinating creature. Learn why in this episode of BrainStuff. 

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Lauren Vogelbaum. Here. If you live in North America, you've
probably seen a Virginia a possum classification to Delphis Virginiana.
Maybe the unfortunate creature was dead on the road, or
maybe it was very much alive on your porch eating
garbage in the middle of the night. But in either

(00:22):
case you might have thought, oh, gross, a possum. But
you would have been off base on several counts. First
of all, possums live in Australia and are also a marsupial,
which means they raise their young in a pouch like
a kangaroo, but they are a completely different species. And
the animal currently snuggling with a half eaten bag of
Doritos at the bottom of a curbside trash can in

(00:43):
North Carolina, which is correctly an a possum. We spoke
with Richard Osfeld, senior scientist at the Caree Institute of
Ecosystem Studies in Millbrook, New York. He said, folks get
very confused about this. I've had people tell me triumphantly
that they discovered building plans for possum nest boxes and
that they planned to install dozens of them to encourage
opossums to multiply on their property. But when I looked

(01:06):
up the plans, they were designed for brush tailed possums
in Australia, completely useless for apossums in North America. So
with that part settled, opossums aren't that gross, even if
they wouldn't mind taking that multipad tie from the back
of your refrigerator off of your hands. They may look
a little creepy, what with that long, hairless, prehensile tail,

(01:27):
the mouthful of haphazard teeth, and the beady eyes, but
apossums are the fastidiously groomed and most likely disease free
wildlife heroes of your neighborhood. It's a common misconception, possibly
prompted by their bumbling swagger, that apossums often carry rabies
or a distemper. In fact, they rarely get these diseases
because their body temperature is too low to make them susceptible.

(01:50):
Not only do apossums not carry these diseases, the presence
of an opossum in your yard is your best bet
for combating lime disease. A two thousand nine study explored
whether black legged ticks. The disease vector for lime disease
might be regulated by wildlife that they parasities of fifteen
forest dwelling mammals and ground nesting birds. Opossums were the

(02:11):
only ones to destroy the vast majority of all of
the black legged ticks that tried to feed on them.
Over Ostfeld, who co authored the study, said, our calculations
indicated that a single opossum is capable of killing several
thousand larval ticks per week during the late summer peak.
We also know that of those ticks that do successfully
feed on an opossum, only a small fraction will become

(02:34):
infected with the lime disease bacterium, so apossums are protective
in two ways, killing ticks and preventing infection. A study
by the same research team published in July ten in
the journal Ecology found that tick born disease risk was
reduced in areas where opossums were present. For an animal
that does more than its fair share of hobbling into

(02:55):
traffic and is known for flopping over like a corpse
at the merest whiff of danger, apossums are perhaps surprisingly
intelligent to begin with weak eyesight at a nocturnal nature.
Both contribute to the fact that you're probably more familiar
with the side of a dead apossum than a live one.
In addition, their primary defense mechanism, playing dead is almost
entirely involuntary, a reaction to extreme stress that leaves the

(03:17):
apostum in a coma for a few minutes to a
couple of hours, and a comatose apossum can take a
beating that would kill other animals their size. This, then,
is a great strategy if your mortal enemy is a bear,
but not so great if it's a toyota. So if,
for example, your dog corners an opossum one night in
the backyard, don't worry. The apostum may hiss and show

(03:38):
its teeth in an attempt to look scary because it's frightened,
but the last thing it wants is to tangle with
your four legged friend. It will invariably lay down and
play dead until the threat gets bored and passes. Apossums
are non aggressive, docile creatures, far more afraid than they
are to be feared, and they're also fastidiously clean. Like cats,
apossums are constantly grimming themselves with their paws and tongue,

(04:01):
partly in order to make sure they're parasite free, but
also to keep themselves cool. They lack sweat glands, so
grooming is like apossum air conditioning, and they do it
to keep themselves smelling like well nothing. As we've established,
apossums aren't great at protecting themselves in a standoff with
a predator, so it behooves them to stay odor neutral.
Part of the reason apossums have the reputation for being

(04:23):
smelly has to do with one other defense mechanism, the
smell of death. Once an opossum goes into its theatrical coma,
if a predator continues to mess with it, the opossum
may excrete a smelly mucus from glands in its anus.
This has been a signal, Hey, this apossum is definitely dead,
and possibly so entirely dead that it'll make you sorry
you ate it. Speaking of, apossums are really smart about

(04:46):
what they eat, because it turns out they have great memories.
Once an apostum tastes a chemical that doesn't agree with it,
it will remember and avoid the smell of it for
a year afterwards. Though apossums are immune to some things,
that would poison other mammals, including most snake venoms. Apossums
are biologically fascinating, which led to some confusion among earlier

(05:07):
Europeans in the New World. Their story was the male
opossum made it through the female apossums snout, which led
to her sneezing out her babies into her marsupial pouch.
Of course, this is not scientifically accurate, but apossums definitely
do things a little differently. First of all, a male
apossum has a forked penis, but it's not meant for

(05:27):
the female's nostrils. Female apossums have a double vagina and
twin uteri. Apostsum embryos developed for about thirteen days until
they're large enough to migrate down the birth canal and
emerge about the size of house flies to continue developing
in the mother's pouch. Although dozens of them will be born,
the mother only has thirteen teats, so that's probably how
many will be able to survive into adulthood. Today's episode

(05:54):
was written by Jescelyin Shields and produced by Tyler Clang.
Brain Stuff is a production of I Heart Radio's How
Stuff Works. For more in this and lots of other
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