10 May 2015

Fleas Knees And Bad Backs

I found this poor dead bee while hoovering (yes, I do occasionally do a spot of housework).

Her wings are beautiful - like a sepia ink pen drawing on parchment.

Bees need flexible wings because the don't simply flap up and down but do a sort of figure of eight shape in the air. There might be a post about that somewhere in this blog, but it'll take some rummaging to find it.

The flexibility is provided by a protein called resilin which is found at the junction of the wing veins. It is used by most insects in body parts that need lots of elasticity. Fleas need it to jump. Cicadas use it to make their famous sound, and it is even in the mouths of insects that pump poison into other insects.

It is a miraculous substance that has near perfect elasticity. Experiments have been done on the resilin in dragonfly wings. Even when strained to over twice its original length for two weeks, a dragonfly's resilin tendon snaps back perfectly when the stress is relieved.

The reverse action of compression is also impressive in that about 97% of the energy that’s put into it is returned. Experiments, on fleas this time, show it is not good at storing energy as such. The ability of fleas to jump isn't due to the resilin. Instead, it allows the body to quickly return to its original shape, ready for the next leap.

It is such amazing stuff that scientists are trying to make artificial spinal discs with it to transplant into humans. Being a sufferer of a bad back I can't wait for that to happen.