Aequorea victoria, also sometimes called the crystal jelly, is a bioluminescent hydrozoan jellyfish, or hydromedusa, that is found off the west coast of North America.

Almost entirely transparent and colorless, and sometimes difficult to resolve, Aequorea victoria possess a highly contractile mouth and manubrium at the center of up to 100 radial canals that extend to the bell margin.

Larger specimens are frequently found with symbiotic hyperiid amphipods attached to the subumbrella, or even occasionally living inside the gut or radial canals.

While A. coerulescens is apparently generally found offshore in the eastern Pacific Ocean, rare specimens have been collected in central California and in Friday Harbor, North Puget Sound.

Shimomura together with Martin Chalfie and Roger Y. Tsien were awarded the 2008 Nobel Prize in Chemistry[3] for the discovery and development of this protein as an important biological research tool.

[5] Aequorea victoria juvenile medusae are asexually budded off hydroid colonies in late spring; these free-living hydromedusae will spend all of their lives in the plankton.

The hydroids live on hard or rocky substrates on the bottom, where they asexually bud new tiny jellyfish each springtime in response to some (still unknown) environmental cue(s).

[6] Prey is ensnared in long tentacles containing nematocysts, and ingested with a highly contractile mouth that can expand to consume organisms half the medusae's size.

[7] Aequorea medusae are eaten by the voracious scyphozoan Cyanea capillata, commonly called the lion's mane jelly, as well as ctenophores, siphonophorae and other hydromedusae, including documented cases of cannibalism.

In 1961, Shimomura and Johnson isolated the protein aequorin, and its small molecule cofactor, coelenterazine, from large numbers of Aequorea jellyfish at Friday Harbor Laboratories.