1 September 2017
Zoologger is
our weekly column highlighting extraordinary animals – and occasionally other
organisms – from around the world
By Michael Marshall
Species: Struthio camelus
Some people just achieve too
much. For instance, Iron Maiden singer Bruce Dickinson is also a qualified
airline pilot, a skilled
fencer and a published novelist – which is frankly galling.
Ostriches are the Bruce
Dickinsons of the bird world. Not only are they the largest living bird
species, they also lay the largest eggs of any bird alive and hold a
Guinness World Record to that effect. And they can run faster.
However, what you may not know is
that they are quite possibly the only animal to have two kneecaps in each leg.
This we’ve known since at least 1864, but why
it should be so has remained a mystery ever since.
Funny bones
To find out, Sophie
Regnault and her colleagues at the Royal Veterinary College in
London, examined a single dead ostrich donated to the college. They alternately
bent and straightened the ostrich’s knees, and used an imaging technique called
biplanar fluoroscopy to track how the bones moved. Then they built a simple
model to understand how the kneecaps affected the leverage of the muscles
controlling the knee.
“The upper kneecap looks similar
to the single bone in ourselves and other animals,” says Regnault. However,
“the lower one is very closely attached to the lower leg bone… a bit like the
point of your elbow.”
Typically, kneecaps improve the
leverage of the knee extensor muscles, so they don’t need to produce as much
force to straighten the knee. “It’s a bit like putting the door handle further
from the hinge,” says Regnault. “It requires less force to open the door.”
No comments:
Post a Comment