Objects falling through the air eventually reach a maximum speed called terminal velocity. This occurs when the downward force of gravity is balanced by the upward force of air resistance. While a fall from significant heights is fatal for many, certain animals possess remarkable adaptations that allow them to survive impacts at their terminal velocity.
Understanding the Physics of Falling
An object falling through Earth’s atmosphere is subject to two primary forces: gravity pulling it downwards and air resistance pushing upwards. Initially, gravity causes the object to accelerate, increasing its speed. As speed increases, the force of air resistance also grows because the object collides with more air particles. Eventually, the upward force of air resistance becomes equal in magnitude to the downward force of gravity. At this point, the net force on the object becomes zero, and it stops accelerating. The constant speed it then maintains is its terminal velocity.
How Animals Defy Gravity’s Impact
Animals capable of surviving high falls share key biological and physical characteristics. A primary factor is their low mass-to-surface area ratio, meaning their weight is small relative to their body surface exposed to air. This maximizes air resistance, slowing their descent. Many also have lightweight, flexible skeletons that absorb impact forces more effectively than rigid structures. They may also spread their limbs or bodies, further increasing surface area and drag. These adaptations allow them to hit the ground with significantly less force.
Meet the Surviving Species
Several animals are known for enduring falls from great heights. Cats, for instance, are famed for their “righting reflex,” an innate ability to orient their bodies mid-air to land on their feet. Their flexible backbone and lack of a functional clavicle allow rapid twisting. Cats also spread their bodies to increase drag and relax muscles, distributing and absorbing impact force. An average cat’s terminal velocity is approximately 60 miles per hour, about half that of a human.
Squirrels also thrive after drops. Their small size and light bodies contribute to a low terminal velocity, typically around 20 to 23 miles per hour. When falling, squirrels instinctively splay their limbs and use bushy tails to create a “parachute effect,” maximizing air resistance and controlling descent. This low terminal velocity and controlled fall allow them to survive impacts.
Insects, like ants, demonstrate remarkable resilience. Due to their minuscule mass and large surface area, an ant’s terminal velocity is extremely low, often around 4 miles per hour. At this speed, impact force is negligible, and their tough exoskeletons provide sufficient protection. Most insects do not accelerate to a damaging speed, so falling from any height does not result in injury.
The Critical Role of Size
An animal’s size is the primary determinant of its ability to survive a fall from terminal velocity. Smaller animals have a significantly higher surface area-to-mass ratio, allowing air resistance to quickly balance gravity. This leads to a much lower terminal velocity for small creatures. A lower terminal velocity translates directly to a softer landing, as impact force is proportional to the square of velocity. For large animals, like humans or elephants, their high mass-to-surface area ratio results in a much higher terminal velocity. The sheer force generated at these speeds is too great for their bodies to absorb without severe injury or death, making a fall from sufficient height almost always fatal.