Opossums are strange little creatures that tend to fascinate and confuse people in equal measure. One of their most distinctive behaviors is opening their mouths wide open for seemingly no reason. If you’ve ever seen an opossum with its mouth agape, you probably wondered why it was doing that.
If you’re short on time, here’s a quick answer to your question: Opossums open their mouths as a defensive tactic to appear threatening to potential predators. This instinctive behavior is meant to scare away predators by making the opossum look fierce.
In this nearly 3,000 word article, we’ll explore this curious opossum behavior in depth. We’ll look at the reasons why opossums open their mouths, what they are trying to communicate, and how this relates to their physiology and defense mechanisms.
We’ll also examine some common myths and misconceptions about gaping opossums. Whether you want to understand opossum behavior better or just satisfy your curiosity, you’ll find a comprehensive explanation here.
It’s an Instinctive Defensive Reaction
Makes Them Appear Threatening
When opossums bare their sharp teeth and open their mouths wide, they are trying to look as scary and intimidating as possible to potential predators. This reaction is instinctive and helps protect them from harm.
Research shows that by gaping their mouths open to reveal 50 razor-sharp teeth, opossums appear much larger and more threatening than they actually are. The inside of their mouths also sports a terrifying dark cavity that mimics the look of a dangerous snake or other primal beast (Opossum Society).
Shows Off Their Sharp Teeth
Opossums have more teeth than any other North American land mammal, with 50 pointed teeth designed to rip and shred food (Encyclopedia Britannica). By gaping their mouths open wide, opossums showcase their formidable teeth arsenal.
This teeth-baring display serves as a clear warning to predators that this seemingly vulnerable creature can inflict some serious damage with one bite if provoked. The sharp fangs remind predators that although opossums may appear like easy prey, they won’t go down without a fight.
Mimics a Snake
Interestingly, when opossums open their mouths wide in self-defense, their dark mouths mimic the look of a dangerous snake. This physical trait likely evolved as an extra layer of protection.
Many predators have an innate fear of snakes and will avoid them at all costs. By resembling a snake ready to strike when threatened, opossums tap into this natural aversion and increase their chances of scarying predators away (National Geographic).
So while an open-mouthed opossum may seem strangely aggressive, it is actually just trying to non-violently protect itself from potential attackers in the only way it knows how – by tapping into predators’ instincts to avoid anything resembling a deadly snake.
It’s Related to Their Body Temperature Regulation
Panting Helps Them Cool Down
Opossums pant and open their mouths as a way to help regulate their body temperature. As mammals, opossums need to maintain a certain internal body temperature to stay healthy. However, since they have relatively inefficient sweat glands compared to other mammals, panting and mouth gaping are the primary ways opossums cool themselves down when they get too hot.
By panting and exposing the moist surfaces of their mouths and throats, evaporation can take place, which helps lower their body temperature. The increased air flow that comes with gaping their mouths also facilitates evaporative cooling. This is similar to how dogs pant to cool down.
Opossums have been observed panting more frequently during hot weather or after exertion. Mouth gaping may be particularly important for opossums in warmer climates like the southern United States. Panting and mouth gaping help them avoid hyperthermia (overheating) in high temperatures.
Exposing the Mouth Helps Release Heat
In addition to facilitating evaporation, simply opening the mouth also releases heat from inside an opossum’s body. The inside of an opossum’s mouth and throat contains many blood vessels close to the surface, which allows heat to radiate out.
Exposing these blood vessels to the cooler outside air by gaping helps the opossum offload excess internal body heat. This heat exchange depends on the temperature gradient between the opossum’s internal body temperature and the external air temperature.
Opossums have been documented gaping their mouths even in cool weather, suggesting mouth gaping aids in routine body temperature regulation, not just when they are overheated. The mouth and throat likely provide an effective area for opossums to release heat and keep their temperature in a healthy range.
What Myths and Misconceptions Exist About This Behavior?
Myth: It Means They Are Rabid
A common myth is that when opossums open their mouths, it signifies that they have rabies. However, this is extremely rare according to wildlife experts. Less than 1% of opossums carry rabies, making the chances incredibly low (https://opossumsocietyus.org/faq-opossum/#Do_opossums_carry_rabies).
Their low body temperature of 94-97°F makes it difficult for the rabies virus to survive.
Myth: It’s a Sign of Aggression
Another assumption is that gaping mouths indicate aggression or that the opossum plans to bite. In most cases, this open-mouthed display is solely a bluff tactic. Opossums are not aggressive animals by nature and prefer to avoid confrontation (https://www.wildlifeanimalcontrol.com/opossum-mouth.html).
Their first line of defense is to look vicious to scare off predators. Attacking is rare and used only as a last resort.
Myth: They Are Faking Being Dead
There’s a widespread belief that when opossums bare their teeth, they are “playing possum” and pretending to be dead. However, the open-mouth reaction is an involuntary behavior that occurs when they feel under attack.
Their body goes into shock mode, drooling and becoming catatonic (https://opossumsocietyus.org/faq-opossum/#Why_do_opossums_play_dead). This physical reaction makes them appear lifeless even though they remain fully conscious.
In reality, the opossum mouth gaping is mostly for show. They use it to scare away predators without having to get aggressive. It’s important to debunk myths about this harmless gesture to better understand opossum communication and prevent needless fear.
When Are They Most Likely to Open Their Mouths?
When Frightened or Cornered
Opossums often open their mouths wide when they feel threatened or cornered. This instinctive reaction is their way of trying to appear fierce and intimidating to potential predators. An opossum’s mouth contains over 50 sharp teeth, so by gaping open their jaws, they hope to convince the threat that they are not to be messed with.
This reaction is all just a bluff though, as opossums are docile creatures that prefer to avoid conflict if possible. Some other signs an opossum is feeling frightened include hissing, growling, drooling, and emitting a foul odor from their anal glands.
So next time you stumble upon an open-mouthed opossum, give it some space and let it be on its way. They are just trying to appear tough and scary!
During the Hot Summer Months
Opossums struggle to regulate their body temperature and are especially vulnerable to overheating in the summer. As a result, they often pant with their mouths open to cool down. An opossum has few sweat glands, so panting helps lower their body temperature and prevent their brain from overheating.
Their saliva also helps cool the blood flowing to their brain when their mouth is open. According to research, an opossum’s normal body temperature ranges from 94-97°F but can spike to over 102°F in hot temperatures before they succumb to heat stroke.
That is why they find shade and become most active at night in the summer. But even in the daytime, you may spot them with gaping mouths as they try to cool down. Just be sure to give them space and hydration during heatwaves so they can thermoregulate!
When Exerting Themselves
Opossums often open their mouths while exercising strenuously or carrying something heavy. For example, you may see them panting with their mouth agape as they scurry up a tree or lug a food pile back to their den. This allows more oxygen to enter their lungs and prevents hyperventilation.
According to wildlife experts, an opossum’s normal respiratory rate is around 14-18 breaths per minute. However, this can double to 30-36 breaths per minute when they engage in intense physical activity. Their elevated heart rate while active also increases blood circulation.
So by gaping open their mouth, opossums release heat and take in more air to meet their body’s increased oxygen demands. Just like humans, they need more air when exerting themselves! So an open-mouthed opossum could just be catching their breath after intense exercise.
Other Odd Opossum Behaviors Explained
Playing Dead
Opossums are famous for “playing dead” or “playing possum.” This instinct comes from the marsupial’s innate biology – when extremely threatened, fearful, or stressed, opossums will enter an abrupt comatose-like state that can last for hours.
Their heart rates slow dramatically, and they appear limp and unconscious. This involuntary reaction likely evolved as an effective defense mechanism against predators.
Around 40-50% of healthy opossums play dead when threatened, according to wildlife research. Juveniles tend to maintain the stiff, comatose pose longer than adult opossums. What’s interesting is that an opossum’s nervous system overrides their basic survival instincts during this period.
The opossum becomes temporarily oblivious to extreme heat, cold, loud noises, and physical touch. They are locked into their catatonic state until the perceived threat retreats.
Baring Their Teeth
You may catch an opossum “grinning” or bearing its teeth at you. This reflex exposes the marsupial’s 50 extremely sharp front teeth. An opossum will often bare its fangs when frightened or agitated. It’s an instinctual attempt to seem more threatening to predators.
However, this act is all bluff – opossums are essentially docile, nonconfrontational animals. Their hisses and gaping smiles are almost always just posturing self-defense mechanisms.
Interestingly, opossums have more teeth than any other North American land mammal – 50 in total. This includes 28 sharp needle-like teeth at the front of their mouths. You can see all 50 when an opossum fully opens its jaws.
Hissing and Growling
Like other defensive behaviors, opossums will hiss, growl, and cry out when scared or angered. These vocal warnings make the timid marsupial seem much fiercer than their personality suggests. The hisses and cries are instinctual but harmless – opossums aren’t looking for a fight.
Momma opossums carrying young may be more prone to aggressive vocalizations. They instinctively protect their babies at any perceived threat. Interestingly, opossum “screaming” is a high-pitched sneeze-like sound. This is thought to mimic a snake’s warning hiss and further deter potential predators.
Opossums use a wide repertoire of clicks, hisses, growls and screams to communicate fear, distrust, assertions of territory, and protectiveness of young. The more intimidated an opossum feels, the more ferocious its voice may sound as self-defense instinct takes over.
Conclusion
Hopefully this article has satisfied your curiosity about why opossums often sit there with their mouths wide open. Now you understand that this strange behavior is a natural defensive reaction meant to stave off predators.
You also know some of the other reasons opossums might gape their jaws, like regulating their body heat on hot days. While these mammals may look peculiar when they stare open-mouthed, their motivations make biological sense once explained.
Opossums are fascinating creatures with many biological adaptations that aid their survival. Next time you come across one with its mouth agape, you’ll no longer be confused but rather appreciative of its instinctive defenses.
Their dramatic gaping mouths that once seemed so bizarre are just a small part of the opossum’s intriguing suite of behaviors and traits.
