- The eyes of the animal kingdom
- In contrast, the box jelly boasts 24 eyes, which are dark brown and grouped into four clusters, called rhopalia. Nilsson shows me a model of one in his office: It looks like a golf ball that has sprouted tumors.
- Jellyfish can sense their world around them, even without eyes
- Different species have differing abilities to take in the world around them through an organ similar to an eye called a rhopalium.
- Instant Body Plans: The Case of Jellyfish
- The rhopalium is the sensory structure that contains ocelli (pigmented photosensitive structures), statocysts (gravity receptors), and pacemaker neurons that set the basic swim rhythm.
Rhopalium is described in multiple online sources, as addition to our editors' articles, see section below for printable documents, Rhopalium books and related discussion.