No common name

Aequorea victoria

ORDER Conica

FAMILY

Aequoreidae

TAXONOMY

Mesonema victoria Murbach and Shearer, 1902, British Columbia, Canada.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Hydroid: small colonies, unbranched, with creeping hy-drorhiza; pedicels twice as long as hydrotheca. Hydrotheca thin, with an operculum made by many flaps not articulated to hydrothecal rim that converge and close the theca when the hydranth is contracted. Hydranth has 20 tentacles, with an in-tertentacular membrane at base; gonotheca of thin perisarc, originating right below the theca; a single medusa bud.

Medusae are small at liberation, with two tentacles and four radial canals. They can grow up to 4.7 in (120 mm) wide and 1.5 in (40 mm) high. Umbrella saucer shaped to hemispherical, a thick hemispherical projection of mesoglea protrudes into the manubrium; lips of manubrium are fringed and can close the manubrium completely on the sides of the mesogleal projection. Tentacles can be up to 150, lip lobes are usually half the number of tentacles. Each tentacular bulb has an abaxial pore connecting the circular canal to the outside.

DISTRIBUTION

Northeastern Pacific. (Specific distribution map not available.) HABITAT

The hydroid grows on mussel shells. The medusae are planktonic, in coastal and open waters.

BEHAVIOR

The function of the hemisphercal mesogleal projection into the manubrium is to allow the closed mouth to rotate around it, thus pushing the contents of the stomach into the radial canals. The pores in the circular canal are used to eject undigested materials and are more anal pores than excretory pores (as they are commonly called).

FEEDING ECOLOGY AND DIET

Unknown for the hydroid, whereas the medusae have been reported to feed on fish larvae and on gelatinous plankton.

REPRODUCTIVE BIOLOGY

The hydroid is tiny and rarely observed, as are the newly released medusae. Medusa production, however, is very intense, since the species can be present in swarms. The swarms produce great quantities of planulae to support future blooms through the hydroid generation.

CONSERVATION STATUS

The massive use of this species to extract the bioluminescent enzyme aequorein might have some influence on population viability.

SIGNIFICANCE TO HUMANS

By feeding on larvae, it might have a negative impact on fish recruitment; but it has a great role in experimental biology because of its bioluminescent enzyme. ♦

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