Why do penguins have knees if most species do not use them?

Question

What is the point of having them? Can you tell which species use them?

Answer 1

All species of birds use their knees. Most of the time the actual knee is covered under the feathers of the body of the bird. This plays a key role in extending the leg forward and helping to thrust the body forward when the foot is pressed against the ground. Humans have an incredibly long femur and very, very short ankles and feet when compared to a bird. What is often mistaken for a backwards knee on a bird is actually the ankle. The knee in conjunction with the ankle, hips, and multiple joints in the foot and toes helps to give a mechanical advantage to the speed and stability of the animal's movement. Movement can be accomplished by the hips alone, in that the legs will be moved forward, but the other joints most importantly give extreme control to the movement.

Penguins require knees so that their movements on land will be efficient and well controlled. Under water, the feet can be used to push against water to aid in swimming. In the process the knees, ankles, and various joints of the foot and toes are used to multiply the force exerted.

Answer 2

Penguins do have knees. It's just that their legs are short and located so far back on their bodies that it only looks like they don't have them. Having the legs so far back also gives them their characteristic upright stance. All species use them, especially the smaller and more active ones like rockhoppers and Adelies.

Answer 3

all birds have knees, but they bend backwards which is opposite to ours.

This allows them to land on branches easier with their feet first and body balanced. If they had knees like ours, they would have difficulty landing because their feet would be behind them and knees out front.

flightless birds don't rely on this function as much, but it is just a bird thing built into their genetic make up

Answer 4

penguins have knees because they have to jump into the water(you need knees to jump)

Answer 5

They do squat when they are hatching eggs. That involves use of joints in the legs. So they do use their knees.