[4] They typically range from 2 to 40 cm (1 to 15+1⁄2 in) in diameter, but the largest species, Cyanea capillata can reach 2 metres (6 ft 7 in) across.

The nematocysts are located throughout the tentacles that radiate downward from the edge of the umbrella dome, and also cover the four or eight oral arms that hang down from the central mouth.

[5] Scyphozoans usually display a four-part symmetry and have an internal gelatinous material called mesoglea, which provides the same structural integrity as a skeleton.

Scyphozoans have no durable hard parts, including no head, no skeleton, and no specialized organs for respiration or excretion.

[8] The periodic contracting and relaxing propels the jellyfish through the water, allowing it to escape predation or catch its prey.

[5] The nervous system usually consists of a distributed net of cells, although some species possess more organised nerve rings.

There are between four and sixteen of these small lobes arranged around the rim of the umbrella, where they coordinate the muscular action allowing the animal to move.