Atolla jellyfish
The body of "Atolla wyvillei" is a bell shape and it has several moderately long tentacles along the bell. The bell is around 20–174 mm in diameter. It also has a single long tentacle called a hypertrophied tentacle. This hypertrophied tentacle has several purposes, including aid in predation and aid in reproduction. These jellyfish do not have a digestive system, a respiratory system, a circulatory system or a central nervous system. Not having a central nervous system means that it lacks a brain.
Cyanea nozaki
A number of species of juvenile fish associate with this jellyfish, making use of the protection provided by its stinging tentacles. The razorbelly scad ("Alepes kleinii") and Malabar trevally ("Carangoides malabaricus") are two such fish; large numbers of tiny fish congregate around and among the fine tentacles. Each fish either avoids touching the tentacles or is relatively unaffected by their mild sting, and if the jellyfish is netted, the little fishes stay with it and may get more heavily stung, and consequently die. As they get larger, the fish leave the jellyfish and live independently.