Aurelia aurita

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Aurelia aurita
An adult Aurelia aurita
Scientific classification
Kingdom: Animalia Phylum: Cnidaria Class: Scyphozoa Order: Semaeostomeae Family: Ulmaridae Genus: Aurelia Species: A. aurita
Binomial name
Aurelia aurita Linnaeus, 1758

Aurelia aurita (the jelly, crystal jellyfish, moon jellyfish, common jellyfish, saucer jelly, or swimming jellyfish) is the most common jellyfish species found in the genus Aurelia. Other species found in the genus Aurelia besides A. aurita include A. labiata and A. limbata. There are at least 13 species in the genus Aurelia including those that are still not described (Dawson, 2003). They can be found in the Atlantic Ocean, the Arctic Ocean and the Pacific Ocean, and are common to the waters off California, Japan, the East Coast of the United States as well as Europe. The animal is translucent, can be 25-40 cm across, and has characteristic patterns of color within its body. It feeds by stinging small medusans, plankton and mollusks with its tentacles and bringing them into its body for digestion, but is capable of only limited motion; like other jellies it drifts with the current.

Contents 1 Biology 2 Feeding 3 Filtering Grid 4 Body system 5 Predators 6 References

[edit] Biology

The cosmopolitan Aurelia aurita is found throughout the tropics and as far north as 70° latitude and as far south as 40°. (J.E. Purcell, et al. 2001). In addition to frequenting the North American coast, they are usually found all around the coasts of the British Isles (Russell, 1953). In general, A. aurita is an inshore species that can be found in places like estuaries and harbors (Russell, 1953). They can be recognized by their horse-shoe shaped gonads. They live in ocean water temperatures that range from −6 °C to 31 °C; with optimum temperatures of 9 °C to 19 °C (Rodriguez, 1996). A. aurita prefers mildly cold salt water with consistent currents (Rodriguez, 1996). They can be found in 3 ppt salinity water but are typically found only in water with salinity above 23 ppt.

[edit] Feeding

A. aurita and other Aurelia species feed on plankton that includes organisms such as mollusks, crustaceans, tunicate larvae, rotifers, young polychaetes, protozoans, diatoms, eggs, fish eggs, and other small organisms. Occasionally, they are also seen feeding on gelatinous zooplankton such as hydromedusae and ctenophores (Rodriguez, 1996). Larvae of A. aurita have nematocysts to capture prey and also to protect themselves from predators. The food is tied with mucus, and then it is passed down by ciliated action down into the gastrovascular cavity where digestive enzymes from serous cell break down the food. There is little known about the requirements for particular vitamins and minerals, but due to the presence of some digestive enzymes, we can deduce in general that A. aurita can process carbohydrates, proteins, and lipids (Arai, 1997).

[edit] Filtering Grid

Click on the images for higher resolutions. high resolution in situ image of an undulating live Aurelia in the Baltic showing the grid of the fibres which are slowly pulled through the water. The motion is so slow that copepods can not sense it and don't react with an escape response higher magnification showing a prey item, probably a copepod The prey is then drawn to the body by contracting the fibres in a corkscrew fashion (image taken with an ecoSCOPE).

[edit] Body system

A. aurita does not have respiratory parts such as gills, lungs, or trachea. Since it is a small organism, it respires by diffusing oxygen from water through the thin membrane. Within the gastrovascular cavity, low oxygenated water can be expelled and high oxygenated water can come in by ciliated action, thus increasing the diffusion of oxygen through cell (Rees, 1966). The large surface area membrane to volume ratio helps A. aurita to diffuse more oxygen and nutrients into the cells.

The basic body plan of A. aurita consists of several parts. The species lack respiratory, excretory, and circulatory systems (Arai, 1997). The adult medusa of A. aurita, with a transparent look, has an umbrella margin membrane and tentacles that are attached to the bottom (Russell, 1953). It has four bright circular gonads that are under the stomach (J.E. Purcell, et al. 2001). Food travels through the muscular manubrium while the radial canals help disperse the food (Russell 1963). There is a middle layer of mesoglea, gastrodervascular cavity with gastrodermis, and epidermis (Solomon, 2002). There is a nerve net that is responsible for contractions in swimming muscles and feeding responses (Aria, 1997). Adult medusa can have a diameter up to 40 cm (Arai, 1997). The sexes are differentiated between males and females in the medusa stage (Arai, 1997). The young stage, planula, has small ciliated cells and would settle at the bottom of the water where it would change into strobila and then float off as ephyra (Gilbertson, 1999). There is an increasing size from starting stage planula to ephyra, from less than 1 cm in planula stage to 1 cm in ephyra stage (Russell, 1953).

[edit] Predators

The death of the organism sometimes is brought about after reproduction, leaving the gonads open to infection and degradation (Arai, 1997). A. aurita have been food for a wide variety of predators including the Ocean Sunfish (Mola mola), the Leatherback Sea Turtle (Dermochelys coriacea), a hydromedusa (Aequorea victoria) (Arai, 1997) and the scyphomedusa Phacellophora camtschatica (Towanda and Thuesen, 2006). They are hunted by birds also.

A. aurita is food in countries such as China, Philippines, Thailand, Malaysia, and Indonesia.

There are possible metazoan parasites that attack A. aurita (Arai, 1997).

[edit] References

• Arai, M. N. 1997. A Functional Biology of Scyphozoa. Chapman and Hall, London, 68-206.
• Dawson, M.N. 2003. Macro-morphological variation among cryptic species of the moon jellyfish, "Aurelia" (Cnidaria: Scyphozoa). Marine Biology 143: 369-379.
• Gilbertson, L. 1999. Zoology Laboratory Manual 4^th edition. McGraw-Hill Inc, CA, 9.2-9.7.
• Moen, F.E. and E. Svensen. 2004. Marine fish & invertebrates of Northern Europe. AquaPress: Southend-on-Sea. ISBN 0-9544060-2-8. 608 pp.
• Purcell, J. E., W.M. Graham, and H.J. Dumont (Eds.). 2001. Jellyfish Blooms: Ecological and Societal Importance. Kluwer Academic Publishers, Dordrecht, 229-273.
• Rees, W. J. 1996. The Cnidaria and Their Evolution. Academic Press Inc, NY, 77-104.
• Rodriguez, R. J. February 1996. "Aurelia aurita (Saucer Jelly, Moon Jelly, Common Sea Jelly Jellyfish) Narrative." [1]
• Russell, F. S. 1953. The Medusae of the British Isles II. Syndics of Cambridge University Press, London, 81-186.
• Solomon, E. P., L. R. Berg, and W. W. Martin. 2002. Biology 6^th edition. Brooks/Cole Publishing, CA, 602-608.
• Towanda, T. and E.V. Thuesen. 2006. Ectosymbiotic behavior of Cancer gracilis and its trophic relationships with its host Phacellophora camtschatica and the parasitoid Hyperia medusarum. Marine Ecology Progress Series 315, 221-236.
• National Center for Biotechnology Information. October 23, 2001. [2]