Biologic evolution

The size of scissors of Japanese Freshwater Crab is different in the surgical knife from the male. As for the male, only scissors of the right are growing.


The copulation of the crab copulates while faced each other. Scissors cut when scissors and scissors are mutually placed in that case and it becomes a right hand.

Scissors molt after that.

Japanese Freshwater Crab is a crab that doesn't live with seawater. It is thought that the amount of nourishment of food is a little.

It is thought that scissors have become small for that. It is evolution of scissors.
 
サワガニのハサミの大きさはオスとメスでは違います。オスは右のはさみだけ大きくなっています。


蟹の交尾はお互いに顔を向け合った状態で交尾します。その際にお互いにハサミとハサミを挟む時に、ハサミが切れてしまい片腕になってしまいます。

そのあとハサミは生えかわります。

サワガニは海水で生活をしないかにです。食べ物の栄養量が少ないと考えられます。

そのためにハサミは小さくなっていると考えられます。はさみの進化なのです。