Cubozoans are also known as box jellyfish, because in transverse section the bells appear to be square. Tentacles are located at the corners of the square umbrella margin, and the base of each tentacle is distinctively flattened. The edge of the umbrella turns inward to form a rim called a velarium, much like the velum of hydromedusae.

 

Cubozoans are considered by some to be a subclass of scyphozoa. Effective predators and strong swimmers, they feed mostly on fish. Their nematocysts are especially potent, sometimes resulting in the death of unfortunate human swimmers who encounter them.

 

 

Source:

 

 
• Hickman, C.P. and L. S. Roberts. 1994. Animal Diversity. Wm. C. Brown, Dubuque, IA.
 
• Brusca, R. C., and G. J. Brusca. Invertebrates. 1990. Sinauer Associates, Sunderland, MA.