Compound Eyes and The Visual Field

Compound Eyes And The Visual Field Crab eyes showing pseudo-pupil Crab eyes showing pseudo-pupil Fiddler crab Fiddler crab Fiddler crab Fiddler crab

The Pseudopupil & Resolution

Fiddler crabs can look all around, without the need to move their eyes. Their compound eyes sit on top of long vertical eye stalks.

The black parts of the eye look into your direction. The shape of this pseudo-pupil indicates that more receptors look in vertical than in horizontal directions.