Home >> Science & Nature >> Animals & Science

Which Animals Use Their Tails to Keep Balance?

A tail can be a useful thing. Dogs use their tails to convey their emotions, wagging them frantically when they're happy and tucking them between their legs when they're scared or sad. Horses use their tails to swat flies and other flying insects that use their bodies as rest stops. Rattlesnakes use their tails as a warning signal to ward off anyone or anything they see as potential threats. Crocodiles use their tails as weapons, clubbing their opponents with their strong appendages. Fish use their tails to propel themselves through water. And some species of monkeys treat their tails as fifth limbs, using them to pick up objects and to hold onto tree branches. But for many animals, tails play an even more essential role in their survival: helping them stay balanced.

Balancing Act
- Just like a human uses her arms when trying to stay balanced, an animal will extend its tail to adjust its center of gravity.
  
  The length an animal can extend its body is dependant on the proximity of its center of gravity in relation to its support base. To better understand this principle, imagine placing a barrel on its side and setting a 6-foot-long board across it, leaving 3 feet hanging over either side of the barrel. The board would likely balance with each end about the same distance from the floor, right? That's because the board's center of gravity is directly aligned with its base support, which is the barrel. But if you were to move the center of gravity a foot to the right, what would happen? The right side of the board would tip downward, causing the left side to rise. But if you attached an additional foot onto the left side of the board, it would balance out again. Many animals use their tails like the additional piece of wood in the aforementioned scenario. By extending its tail, an animal can shift its center of gravity and maintain its balance when necessary.
High Fliers
- Without their tails to keep them balanced, birds would have a difficult time perching on power lines.
  
  Few animals likely appreciate the balancing feature of tails more than those that live in high places. In addition to using its tail as a fifth limb, a monkey uses its tail to shift its center of gravity when trying to extend its reach and to maintain balance when leaping from tree branch to tree branch. The same holds true for a squirrel, which will level itself out with its tail if it starts tipping to one side in the midst of a jump. And if a bird didn't use its tail as a counterweight, it would fall forward and dangle upside-down every time it tried to perch on a power line or clothesline.
Terrain Tails
- Kangaroos use their tails to stay level when jumping.
  
  That's not to say plenty of ground-dwellers don't rely on their tails to maintain balance. Because a kangaroo can hop at a speed of 40 mph and clear obstacles more than 10 feet high, it uses its tail to level itself out just like a squirrel does. Muskrats and otters use their tails as rudders, which help them remain upright and maneuver when traveling through water. Using its tail as a different type of rudder is a cheetah, which, as the fastest land animal on Earth, can run as fast as 75 mph. Traveling at such a blurring speed, a cougar relies on its tail to maintain a straight path and navigate sharp turns without taking a spill. Even a rat, which is adept at quickly scurrying across even the narrowest surface, would likely spend a lot of time picking itself up if it didn't have a tail to help maintain its balance.
Untold Tails
- Exactly how many types of animals use their tails to maintain balance isn't known; some animal experts believe nearly all creatures with tails use them to stay level to some degree. Some speculate that animals such as dogs use their tails to keep the center of gravity above their feet so they can stick their heads out further. Even cats, whose tails were once thought to play no role in maintaining balance, are now viewed in a different light following an experiment in which several felines had trouble navigating a ledge when denied use of their tails.

Animals & Science