How many eyes does a horseshoe crab have?
This may depend on what you mean by an “eye.” The horseshoe crab has photoreceptor cells (light sensitive cells) in many places. If you call those collections of light sensitive cells “eyes,” then horseshoe crabs have ten or more eyes. Two of the eyes are large compound eyes, similar to the eyes of insects and other arthropods. You can see the compound eyes on the top of the animal’s shell.
