Hydroids: Hydrozoa

Physical characteristics: The polyp colonies of Aequorea victoria (abbreviated as A. victoria) are small and unbranched and have creeping stems. The outer covering is thin and has a cap made of many flaps. The colony of A. victoria has twenty tentacles connected by a membrane at the base. The medusae of A. victoria are small when they leave the polyp colony, having only two tentacles and four canals. They can grow up to almost 5 inches (13 centimeters) wide and 1.5 inches (4 centimeters) high with as many as 150 tentacles. The umbrella is saucer to half-dome shaped, and the mouth is fringed.

Geographic range: A. victoria lives in the northeastern part of the Pacific Ocean. Specific distribution map not available.

Habitat: The polyp colonies of A. victoria grow on mussel shells. The medusae are plankton in the coastal and open parts of the sea.

Diet: Scientists do not know what the polyp colonies of A. victoria eat. The medusae feed on fish larvae and on jellylike plankton.

Behavior and reproduction: A. victoria secretes, or gives off, a protein that produces a blue light when it reacts with the calcium in seawater. The polyp form and newly released medusae are tiny and rarely seen. Medusa production is very intense, because the species is found in swarms. The eggs and sperm released by these swarms of medusae produce great quantities of larvae.

Aequorea victoria and people: The light-producing protein secreted by A. victoria is used to measure cellular levels of calcium.

Conservation status: A. victoria is not threatened or endangered. ∎