Communication and Perception
Little information is known about communication in Chrysaora quinquecirrha, though it appears to be a colonial species. Some scyphozoans release and react to chemicals in the water during breeding seasons. Due to limited material on cnidarian nervous systems, how these chemicals are interpreted remains unclear. Scyphozoan nervous systems are usually comprised of a scattered net of cells, while some species display more organized nerve rings. In those species where nerve rings appear to be nonexistent the nerve cells form structures called rhopallia, arranged around the rim of the umbrella. Rhopalliums are typically associated with a pair of sensory pits, a balance organ for orientation, and sometimes pigment-cupped ocelli, or “eye spots.”
Commonly these eye-like structures are found in the medusa stage, even though polyps from all cnidarian classes are defined as light-sensitive. Photoreceptors of jellyfish are classified as the ciliary type, meaning one or more adapted cilia form the photoreceptive structure. Rhabdomeric photoreceptors are found in other invertebrate groups, whereas ciliary types are normally found in vertebrate eyes. Therefore, the photoreceptors of cnidarians may belong to the same evolutionary line as those of vertebrates. Extra ocular photosensitivity is prevalent throughout the cnidarians, with neurons, epithelial cells, and muscle cells facilitating light detection.
Other Communication Modes: pheromones
Perception Channels: polarized light ; tactile ; chemical
- Barnes, R. 1974. Invertebrate zoology. Philiadelphia: 3d ed. Saunders.
- Seymour, J., R. Wallèn, K. Nordström, D. Nilsson. 2003. A simple visual system without neurons in jellyfish. Proceedings: Biological Sciences, 270: 2349-2354.
- Stierwald, M. 2004. On the evolution of cnidarian eyes. University of Basel, PhD Thesis: 1-54.