It might seem impossible that an animal could survive any fall, but if we look closely at the wondrous animal kingdom, we'll discover many amazing skills that we thought were impossible.
To survive terminal velocity, an animal must balance its gravity with aerodynamic resistance. Sound complicated? Think of it like this; if an animal can gain enough air resistance to slow its fall, it will hit the ground at a lower speed and walk away relatively unscathed. Here are some animals that can't die from a fall and the unique adaptations that make this possible.
How Big of an Animal for a Fall to Kill it?
There is no specific size that defines whether a fall will kill an animal. But some laws of physics can help explain why smaller animals, such as cats, are more likely to survive a fall from a greater height than a human being.
One of the biggest influences is momentum, which is calculated by the animal's mass multiplied by the speed at which it travels (its velocity). So, the bigger the mass, the bigger the momentum at any given speed. When it stops (i.e., lands on the ground), there's a change in momentum, and the animal experiences an impact force. An animal needs to minimize its impact force to survive a fall.
One way to do this is to increase their air resistance by expanding surface area, as we see with flying squirrels. As the mass of an animal increases, so does its surface area, but the mass increases more quickly than the surface area, which is why most large animals cannot survive big falls.
Which Animals Can Survive Terminal Velocity?
The squirrel may be one of the biggest animals that can survive a fall from any height thanks to the laws of physics. When an object (such as an animal) is in freefall, it has two opposing forces acting on it - gravity (which pulls it down) and aerodynamic resistance (which pushes it up). At some point during the fall, these opposing forces will balance, and the speed of the fall will stabilize.
Therefore, any animal has a terminal velocity or a maximum speed they will reach during a fall. One scientist calculated the maximum velocity of a squirrel at roughly 23 mph or 10.28 m/s. Compare this to a human being in a freefall skydive, and we can reach speeds of 120 mph or 54 m/s.
Thanks to this low rate of terminal velocity, the squirrel can stabilize its speed within the first three seconds of a fall and will travel at the same speed regardless of whether it falls from a tree or the stratosphere. It's hard to imagine, but in both scenarios, the squirrel would hit the ground at the same speed, which would be low enough for it to survive.
Rats, Mice, and Hamsters
Rice, mice, and hamsters are three rodent species that are not guaranteed to survive a fall but stand a good chance. Their low body mass makes it possible for them to survive the impact of terminal velocity with little to no injuries.
Rats and mice fall out of roofs and trees all the time with minimal impact. And when you consider the size of these objects in relation to the tiny height of a mouse or rat, you can appreciate what a feat this is. Still, the size and shape of the rodent are vital to its survival. An ideal body will carry less mass but a larger surface volume, thus increasing the resistance (or drag) during the fall.
One story that illustrates these rodents' potential to survive significant falls is this one, when during the days of coal mining, mice and rats would often fall into open holes, dropping deep underground. But they survived these falls, which is why the mines were infested with rodents.
Hamsters rarely die from falls; if they do, it's usually because of the medium they fall onto. For example, a solid or jagged object could lead to dislocation, fractures, or paralysis, while a fall that breaks the neck would be deadly.
Some animals - such as cats - have bodies specially adapted to survive the impact of a fall. Hamsters have strong leg bones that can absorb the impact of a fall with very little damage, but they must land on all four legs to make the most of this skill. If they don't, they risk breakages and life-threatening injuries.
Spiders, Ants, and Most Insects
Thanks to most insects' light mass, they can survive terminal velocity. "The bigger they are, the harder they fall" still applies in these scenarios, along with some other interesting factors.
Larger spiders (such as tarantulas) have a better chance of surviving a fall if they possess a lot of fur; this fur can help to increase air resistance and acts as a cushion to help soften the blow. And spiders are experts at spinning webs quickly and using silk strings to suspend themselves. All these factors make it rare for a spider to die from a fall.
When it comes to ants (and a range of other insects), their mass is so tiny that the terminal velocity is minimal; combine it with their hard exoskeleton, and it's easy to see how these creatures survive big falls.
Lizards make up the largest group in the reptile family, with a range of over 6,000 members. Of these, multiple species can survive a fall from any height, thanks to their low body mass relative to the surface area.
Geckos, for example, have developed several impressive skills to help them avoid predators, including the ability to shed their tails or camouflage into their environment. And these impressive little lizards have relatively flat bodies, meaning the surface area is considerable in relation to their body weight. Their sticky feet mean that falls are infrequent; still, if they do slip, they will almost always survive (providing they don't land on a sharp object).
Can Cats Survive Terminal Velocity?
When we talk about animals surviving great falls, the cat no doubt springs to mind as the animal we always think of as "landing on its feet." Still, the cat is far larger than any other animal on this list. The cat has impressive skills when it comes to terminal velocity, but its size does differentiate this skill from other smaller animals.
For starters, it takes the cat longer to reach terminal velocity. A 1987 study examined 132 cats who had fallen from multi-story buildings and found that the injuries were worse in felines who fell from five stories than in cats who fell from seven stories. This suggests that a height of around seven stories allows a cat to reach its terminal velocity, stop accelerating, and relax into the fall to enable better distribution on impact.
Still, while this study demonstrated a 90% survival rate (humans are around 5% from a ten-story building), we can't use it as a definitive guideline. The biggest problem with the study is that it was conducted in a veterinary center, so cats that died on impact from a fall would have been less likely to be taken in for treatment.
A cat could die from falling, but they have a far better chance than us (and most other animals) of surviving.