Do Jellyfish Have Eyes?

Jellyfish have eyes, but unlike humans, their eyes are not concentrated in a single organ. Instead, the ability to see is facilitated by a network of nerves and proteins called opsins. The jellyfish's light-sensing organ lies within a structure called the rhopalia, which lies at the edge of the jellyfish's bell. Within the rhopalia are structures that help the jellyfish balance so it can distinguish when it is right-side up, as well as a light-sensing organ called the ocelli. The moon jellyfish and many of its brethren from the class Scyphozoa have a pretty rudimentary ocelli. It can detect light and its intensity, but nothing more than that. Box jellyfish have eyes that are much like our own eyes, complete with a retina, cornea, and a lens. The box jellyfish Tripedalia cystophora has 4 rhopalia, within each of which lie 6 eyes, making a total of 24 eyes!