The eyes (and telson) have it…..

People are terrified of the horseshoe crab’s telson, or tail.  My reaction is: really? The tail is used to help the horseshoe crab get around in the water, like a rudder on a boat, and they also use it to flip themselves over in the water should they be turned over.  However, it is very difficult for the horseshoe crab to do this on land.  Most of the time they need help, human help, to flip over or risk being eaten by birds and other wildlife.

Another interesting fact I recently learned about the horseshoe crab’s tail: there are photoreceptors on the tail.

What is a photoreceptor?  A photoreceptor is basically a cell that responds to light.

Horseshoe crabs also have 9 eyes and their vision, as we understand it, is very poor. However, they use their eyes and the photoreceptors to navigate their environment.

This gives new meaning to the expression “eyes behind your head”.