Amazing facts about crab's eyes.

Picture of a crab.

The eyes of a crab makes it look like an animal from outer space.

The two stalks that seem to be growing out on top of the head are the eyes of a crab.

By means of thousands of light-sensitive facets on each eye stalk, the crab can see all around—360 degrees.

It can detect the altitude and slightest movement of the sun and the moon, and can sense changes in brightness as small as 2 percent.

Some crabs have such keen vision that they can detect a six-foot-tall person 60 feet (18 m) away and run for cover.

Even when hiding in the sand, the crab can send an eye stalk up as a periscope.