Heron’s “Knees”

Update: as a couple of comments below note, these knobby parts are actually the bird’s ankle-equivalents. I was imagining the bee’s knees when I came up with this post…

9 Responses to “Heron’s “Knees””

  1. 1 gkleing3 July 17, 2021 at 10:15 am

    What’s with his knees? Is it an optical illusion or are they at different places on his legs?

    • 3 Chuck McAlexander July 17, 2021 at 4:24 pm

      What we see are ankles, not knees. The knees are up in the feathers. The left is raised higher than the right so the right ankle is lower.

  2. 4 Chuck McAlexander July 17, 2021 at 12:38 pm

    What we think of as the backward bending knee of a bird is actually the ankle. The knee is tucked up under the feathers and bends the same direction as ours. The shin is the tarsometatarsus, or foot bones between the ankle and toes. What we think of as the foot is all toes. Birds started with the same parts we did but came up with a different solution for the puzzle. Fascinating stuff if you’ve a mind to look at it.

  3. 5 Chuck McAlexander July 17, 2021 at 4:17 pm

    Yup, ankles

  4. 6 Chuck McAlexander July 17, 2021 at 4:20 pm

    It’s left knee is raised higher than it’s right knee just as ours would be if standing on a slope.

  5. 7 Paul Lamb July 18, 2021 at 7:09 am

    That top photo is spectacular in its way!

  6. 8 Chuck McAlexander July 18, 2021 at 9:25 am

    Think of the last roasted chicken you carved. The knee is at the distal(outer) end of the thigh. The foot starts at the distal end of the drumstick, but we usually don’t see the bird’s foot unless you buy a game bird from a butcher. They include a severed foot to prove you got a pheasant, not a chicken. That the foot is so drastically modified is is not intuitive at first glance. We assume that the joint about half way down the part of the leg we can see is the backward bending knee. The assumption is wrong. That is the ankle and foot bones fused into the tarsometatarsal. It’s all tendons and no meat so we dispose of it. But it is also a brilliant way to lighten the part of the leg that does the fast moving. The massive muscles which power the legs and feet are moved closer to the bird’s center of mass. The bird is faster, better balanced and can withstand cold temperatures for long periods because the muscles are less exposed than if they were on the foot.
    Brilliant adaptation!

  7. 9 gkleing3 July 18, 2021 at 11:53 am

    Yup. I agree. Fascinating. Thanks for the conversation.

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