Life Cycle of the Moon Jellyfish

Life Cycle of the Moon Jellyfish (Aurlia aurita)

Kingdom: Animalia

Phylum: Cnidaria

Class: Scyphozoa

Order: Semaeostomeae

Family: Ulmariidae

Genus: Aurelia

Species: aurita

Aurlia aurita, commonly called the moon jellyfish, got its name because of its translucent circular bell. The moon jellyfish, Aurlia sp., has a smooth, saucer shaped body with eight lobes along the edge of the bell called the bell margin. Along the bell margin are little cilia, which are referred to as marginal tentacles. The marginal tentacles may have a mild sting but is harmless to most humans. There are four horseshoe shaped stomach pouches that make a four-leaf clover in the middle. Directly underneath the food pouches are the gonads. The moon jellyfish also has four white, frilly appendages surrounding the mouth referred to as oral arms.

There are both male and female moon jellyfish that reproduce sexually. The distinction between male and female is that "females hold the fertilized eggs, which appear as whitish-gray clumps" (Aurelia), on the oral arms. "During reproduction, the male releases sperm through its mouth into the water column" (Buddin). The sperm swim through the water column into the female's mouth in a kind of 'hit or miss' style of fertilization. "Female jellyfish pick up strands of sperm floating in the water released from males, and fertilize themselves internally" (MarineBio). After fertilization, a zygote is formed. To maximize fertilization, Aurlia sp. travel in large groups called smucks. As the moon jellyfish journey through the ocean there are greater chances of zygote formation in Aurlia sp. when they travel together in high numbers. Males use the water column to maximize fertilization rates. The oral arms hold the zygotes until they develop into free-swimming larva.

Aurelia sp. goes through alternation of generations between the polyp stage and the medusa stage. The zygote matures and is released by the female as a planula larva, which is a free-swimming stage. After this stage, is becomes sessile and attaches to a substrate where it enters the polyp stage. In the polyp stage, it asexually reproduces forming other polyps into a column called a strobila. Each of the polyp buds break off into their ephyra form. Each ephyra "reach maturity at around 3 months. However, some ephyrae may take up to two years to grow into sexually-reproducing adult medusae" (Heard). When they are mature medusas, the alternation of generations begins again.

When the free-swimming planula larva enters into the sessile stage and attach to a substrate is a very important stage and has to do with why they are all over the world. At this point the larva attaches to anything hard such as rocks, piers, but more importantly boats. They become attached to barges and get transported from one port to another port. The transportation given by the attachment to boats, moon jellies can be transported all over the world. Also, their body composition is ninety-five percent water and can be carried by ocean currents. When they got transported into the Gulf of Mexico, they multiplied at a very fast rate. The jellyfish are in an "ecosystem free from natural predators