Short bigeyes were named for, you guessed it, their big eyes. They’re usually found on deep rocky bottoms. They’re nocturnal and they prey on smaller fish at night. The size of their eyes maximizes the amount of light that they see in the dark. Also, because they’re red, they appear black in the deep ocean (you might remember this from the ruby sea dragon; red is the first color to be absorbed by water, making them invisible to predators).
In comparison, sea hares have tiny eyes that can only detect light. Their eyes don’t seem to be too sensitive (I know this because I’ve accidentally poked them). Take a look- they’re actually located below their rhinophores, or “bunny ears”: