Zoo-ology column: Get a grip! (prehensility)
May 8, 2011 at 12:08 a.m.
By Judie Farnsworth
Prehensile - The quality of an appendage or organ adapted for grasping or holding.
Fully prehensile appendages help an animal find and eat food and can support weight.
When we hear the word prehensile, a monkey's tail is often the first thing that comes to mind - and that's correct - but there's more.
Prehensility may also refer to noses, hands, feet, claws, tongues and even lips.
To carry the definition a little further; prehensility gives a species the benefit of being able to manipulate things in their environments to help in feeding, grooming, defense and digging.
The next time you visit The Texas Zoo, check out our Baird's tapir. He has a short prehensile snout, or proboscis, that's actually an extended nose and upper lip. It's made up of soft tissue, is very flexible and can move in all directions. He can grab branches and strip leaves, as well as take fruit.
The trunks of elephants are also prehensile.
There's a species of tree porcupine in South America with an unspined prehensile tail. Monkeys, opossums, seahorses, geckos, chameleons and a species of skink are some of the many animals with these tails.
Fossil records show prehensile tails in lizards going back 200 million to 250 million years ago during the Triassic period. Many mammals with a gripping tail have a bare patch called a friction or tactile pad to help them hold on.
Monkeys and some lemurs and lorises have prehensile hands, not paws, to differing degrees. Opposable thumbs like ours, that move freely and independently are the significant factor that defines a hand.
Monkeys also have prehensile feet, as do opossums and squirrels. Ever pick up something with your toes? Yes - you, too, may have a degree of prehensility in your feet. You're just not as dexterous without opposable big toes.
The claws of cats are considered to be prehensile.
Strange as it may seem, the tongues of giraffes and the lips of horses, llama's, black rhinos', manatees' and more are prehensile. The giraffe's 18- to 20-inch tongue is adept at sorting leaves from thorns on acacia trees and for grooming.
The black rhino has a pointed or hook-lip that works like a finger for grasping plants. The white rhino's lip is square, and not prehensile.
Without hands, manatee's lips help them eat. Their large upper lip is split with each side moving independently, letting them manipulate things.
Our Texas Zoo spider monkeys would be happy to show you their fabulous, long, prehensile tails when you visit. Can you see the tactile pad? Watch how they use their hands and feet.
What other animals can you find with prehensile ability?
Judie Farnsworth is a longtime volunteer at the Texas Zoo, specializing in educational programs.