Aurelia auritaMoon jellyfish

Geographic Range

Aurelia aurita are found near the coast, in mostly warm and tropical waters (but they can withstand temperatures as low as -6 and as high as 31 degrees Celsius). They are prevalent in both inshore seas and oceans.

Habitat

Their habitat includes the costal waters of all zones, and they occur in huge numbers. They are known to live in brackish waters with as low a salt content as 0.6%. Decreased salinity in the water diminishes the bell curvature, and vice versa. An optimum temperature for the animals is 9 - 19 degrees Celsius.

Physical Description

These animals range between 5 and 40 cm.. They can be recognized by their delicate and exquisite coloration, often in patterns of spots and streaks.

Reproduction

Sexual maturity in Aurelia aurita commonly occurs in the spring and summer. The eggs develop in gonads located in pockets formed by the frills of the oral arms. The gonads are commonly the most recognizable part of the animal, because of their deep and conspicuous coloration. The gonads lie at the bottom of the stomach. Males and females are distinct and reproduction is sexual.

  • Parental Investment
  • no parental involvement

Behavior

Their behavior depends on a number of external conditions, in particular, food supply. Aurelia swim by pulsations of the bell-shaped upper part of the anima. Swimming mostly functions to keep the animal at the surface of the water rather than to make progress through the water. They swim horizontally, keeping the bell near the surface at all times. This allows the tenticles to be spread over the largest possible area, in order to better catch food. The coronal muscle allows the animal to pulsate in order to move. Impulses to contract are sent by way of the subumbrellar nerve net and are nervous in origin. The Moon Jelly has rhopalial centers, which allow it to control the pulsations. As the oxygen rate in the water goes down, so too does the resiratory rate of the jellyfish.

Food Habits

The Saucer Jelly is carnivorous and feeds on plankton. Their primary foods include small plankton organisms such as mollusks, crustaceans, tunicate larvae, copepods, rotifers, nematods, young polychaetes, protozoans, diatoms, and eggs. They are also sometimes observed to eat small hydromedusae and ctenophores. These foods collect chiefly on the surface of the animal, where they become entangled in mucus. Food items are then passed on to the margins by flagellar action, where they collect on the lappets. They are then moved, again by flagellar currents, along eight separate canals, which are unique to this species of jellyfish. These canals branch off and run into the stomach, and they bring the food to it via the ring canal.

Economic Importance for Humans: Positive

Represent an important step in pelagic organic matter transformations.

Economic Importance for Humans: Negative

Predation on copepods and fish larvae. May significantly affect a plankton community through predation.

Conservation Status

They are very plentiful.

  • IUCN Red List [Link]
    Not Evaluated

Contributors

Roberto J. Rodriguez (author), University of Michigan-Ann Arbor.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

References

Coleman, N. 1991. Encyclopedia of Marine Animals. Blandford: London, U.K. 33.

Hernroth, L. and Grondahl, F. 1983. On the Biology of Aurelia Aurita. Ophelia, 22(2):189-199.

Hyman, L. 1940. The Invertebrates: Protazoa through Ctenophora. Mc Graw Hill Inc., New York. 497-538.

Malej, A. Faganeli, J. and Pezdic, J. 1993. Stable isotope and biochemical fractionation in the marine pelagic food chain. Marine Biology, 116(4): 565-570.