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Opossums may not win a beauty pageant anytime soon, since these marsupials look similar to oversized rats, but they actually aren’t nearly as gnarly as they appear. In fact, they’re one of the most unique animals in Iowa, and they have ecological benefits in both natural and urban environments. So the next time you see one of these little foragers, think about what good they might be doing for you instead of grabbing the broom.
That’s Not My NameWhile many Iowans omit the “o” and just say ‘possum, opossums and possums are actually very distinct animal lineages from separate continents. Opossums live in all over the western hemisphere, and the name opossum can refer to animals from over 100 species. Possums, on the other hand, are native to Australia and include about 70 species. The two families do have a strong resemblance in some aspects, but Australian possums eat less meat, have proportionally larger eyes and rounder faces - all of which have helped them earn a more positive reputation among humans than western opossums.
Rabies ResistanceMost common Iowa mammals, like raccoons and skunks, are subject to some parasites and diseases, including rabies. This has particular negative implications for humans, as an animal infected with rabies may become aggressive and infected bites lead to emergency room visits for treatment. On the bright side, opossums are very unlikely to carry rabies. Their body temperature is too low for the rabies virus to thrive in, thus they are less prone to the disease.
Not Dead YetSpeaking of resistance, opossums are immune to some heavy-duty snake venoms. A bite from a rattlesnake or copperhead would normally spell death for just about anything opossum-sized, as these snakes’ venoms contain chemical compounds that reduce the blood’s ability to clot. In opossum blood, the protein that the venom would normally attack has small variations in its genetic code that render the attacking venom ineffective, but don’t otherwise affect normal protein function. Thus, opossums can actually consume these snakes as prey.
Tons of TeethA common territorial or threatened behavior for opossums is to hiss and bare their teeth. Perhaps this display is so effective because opossums have the highest number of teeth of any North American mammal. Still, their 50 little chompers may not be as nasty as they seem. Opossums are opportunistic omnivores, and will eat a variety of foods including fruit, grass, nuts, worms, garbage, carrion, and unattended pet food. To avoid inviting an opossum to your door, keep pet food dishes inside and close pet doors at night.
Playing ‘PossumShould worst come to worst, the opossum is prepared. If they come across a threat that they don’t expect to fend off, the opossum will keel over and appear as dead as possible for several hours. There is debate as to whether this reaction is voluntary or not, but the duration of the behavior and apparent inability to stop at will suggest the reaction is involuntary. The mouth falls open and the tongue lolls out, breathing and heart rates drop dramatically, and the possum will even emit feces and a foul-smelling green liquid from its anal glands to smell as dead as possible. Brain activity, however, remains unaffected, and the opossum is fully conscious. If the reaction is indeed involuntary, it may be similar to experiencing sleep paralysis.
Itty-Bitty BabiesOpossums are the only marsupials north of Mexico. As such, their birthing and parenting strategies differ significantly from those of most mammals. Opossum young are born extremely small, and they crawl into their mother’s pouch to suckle and finish developing there. Normal litters range from seven to 21 offspring, but as many as 50 dime-sized babies may be born in a single litter. Many will not survive long because the mother only has 13 teats in her pouch, with 12 arranged in a circle and one in the center. Once they mature enough, the babies climb out of the pouch and onto their mother’s back. On average, eight or nine joeys survive to adulthood, eventually leaving their mother after three to four months. She may have as many as three litters in a single year, with the average being two.
Getting HandsyAs you may have seen from their tracks, opossums have rather hand-like back paws. The muscular opposable thumbs on these feet help the animal climb and hang with ease. Their hairless tail is also prehensile, and may be used for support or balance while climbing. Opossums sometimes dangle from their tails alone, although this behavior is more common in juveniles.
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