What's an opposable thumb?

Question

Its for Science, thanks.

(Oh and birds can sit on a telephone line. Does that mean their feet have opposable thumbs?)

Answer 1

Yes birds do have an opposable thumb er ah claw. The thumb is located on your hand opposite your fingers so they can come together and grasp things,

this article in the middle explains the bird claw
http://www.tamu.edu/univrel/aggiedaily/news/stories/01/021601-7.html

Answer 2

In human anatomy, the thumb is the first digit on a hand. The human thumb is fully opposable to the tips of the other fingers in that it may position itself, and be folded inward, toward the rest of the hand and fingers, if so required. It rotates at the carpometacarpal joint and so can complete the sometimes quite delicate task of grasping objects by pressing them against the rest of the hand or finger(s).

Humans are able to touch the pad of their thumb to the pad of any other finger on that hand, or if they wish they can turn the thumb so that the thumb pad faces the same direction as the other fingers. That is what it means to be opposable.

Many animals, primates and others, also have some kind of opposable thumb or toe:

Bornean Orangutan - opposable thumbs on all four hands. The interdigital grip gives them the ability to pick fruit.
Cebids (New World primates of Central and South America) - some have opposable thumbs
Chimpanzees have opposable thumbs on all four hands.
Koala - opposable toe on each foot, plus two opposable digits on each hand
Opossum - opposable thumb
Panda - Panda paws have five clawed fingers plus an extra bone that works like an opposable thumb. This "thumb" is not really a finger (like the human thumb is), but an extra-long sesamoid bone that works like a thumb.

In birds the fifth digit is lacking from the foot, and the first, or hallux, is directed backwards in most birds as an adaptation for perching. It is naturally directed backwards toward the other "toes". It is not prehensil or opposable because they cannot switch it to face the same direction as the rest of the "toes". But then, considering it is actually a foot, I guess they are one up on us, because none of our toes are opposable!!!

Answer 3

The human thumb is fully opposable to the tips of the other fingers in that it may position itself, and be folded inward, toward the rest of the hand and fingers, if so required. It rotates at the carpometacarpal joint and so can complete the sometimes quite delicate task of grasping objects by pressing them against the rest of the hand or fingers.

Answer 4

An opposable thumb is one with which you can touch all other fingers on your hand and it allows humans to grip. It is one of the major differences between the ape and the human.

Chow!!

Answer 5

It means that the thumb moves in a direction opposite that of the fingers. Birds do not have thumbs. They have toes, claws or talons.

Answer 6

You have one each hand, it allows you to make and use tools. No to the birds ?

Answer 7

look at your hands...no birds don't have them!
Get an encyclopedia!

Answer 8

look at your hands.