Elongated Eyes
Elongated Eyes
Fiddler crab compound eyes are not round, but vertically elongated (not quite as extreme as the eye of a ghost crab shown here).
The angle between the directions of view of neighbouring ommatidia depends on the local radius of the eye:
Large eye radius = small interommatidial angles = better resolution.
Figure 1: The elongated eye of the Ghost Crab (left); the relationship between the eye radius and interommatidial angle (right).