Aurelia (cnidarian)

fjord, Sweden The similar appearances of moon jellyfish species is what has made them so hard to identify. They tend to have a variety of different sizes, however, they typically range in diameter with an average of wide and in height. The polyps of these jellyfish can grow to tall and their ephyrae have an average diameter of . The basic body plan of Aurelia consists of several parts. The animal lacks respiratory, excretory, and circulatory systems. The adult medusa of Aurelia, with a transparent look, has an umbrella margin membrane and tentacles that are attached to the bottom. Their polyps usually have around 16 tentacles (although Aurelia insularia has 27–33 tentacles) which mostly help with feeding. The large surface area membrane to volume ratio helps Aurelia diffuse more oxygen and nutrients into the cells. Food travels through the muscular manubrium while the radial canals help disperse the food. There is a nerve net that is responsible for contractions in swimming muscles and feeding responses. ==Species==

The following species of Aurelia is accepted by the World Register of Marine Species: • Aurelia aurita (Linnaeus, 1758) • Aurelia ayla Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia cebimarensis Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia clausa Lesson, 1830 • Aurelia coerulea von Lendenfeld, 1884 • Aurelia colpota Brandt, 1835 • Aurelia columbia Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia dubia Vanhöffen, 1888 • Aurelia hyalina Brandt, 1835 • Aurelia insularia Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia labiata Chamisso & Eysenhardt, 1821 • Aurelia limbata Brandt, 1835 • Aurelia malayensis Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia maldivensis Bigelow, 1904 • Aurelia marginalis Agassiz, 1862 • Aurelia mianzani Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia miyakei Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia montyi Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia mozambica Brown & Gibbons, 2021 • Aurelia persea (Forsskål, 1775) • Aurelia profunda Frolova, Mammone & Miglietta, 2025 • Aurelia pseudosolida Garić & Batistić, 2022 • Aurelia rara Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia relicta Scorrano, Aglieri, Boero, Dawson & Piraino, 2016 • Aurelia smithsoniana Lawley, Gamero-Mora, Maronna, Chiaverano, Stampar, Hopcroft, Collins & Morandini, 2021 • Aurelia solida Browne, 1905 • Aurelia vitiana Agassiz & Mayer, 1899 File:Moonjellyfish2500ppx.JPG|Aurelia sp. from the Monterey Bay Aquarium File:Aurelia aurita (aka).jpg|A damaged Aurelia sp. individual File:Aurelia aurita 2.jpg|An adult Aurelia aurita File:Ecomare - oorkwal (pcd01079-oorkwal).jpg|On the beach File:Ecomare - oorkwal (oorkwal-7-pk).jpg File:Aurelia aurita dead on the beach.jpg|Aurelia aurita washed up on the beach, Jūrmala File:Aurelia aurita 2024-05-21 JM 5D412204.jpg|Aurelia aurita at Ozeaneum Stralsund == Distribution and habitat ==

Aurelia species inhabit worldwide habitats.It is found in the North, Black, Baltic and Caspian Seas, Northeast Atlantic, Greenland, northeastern USA and Canada, Northwest Pacific and South America. In general, Aurelia is an inshore genus that can be found in estuaries and harbors. ) Aurelia live in ocean water temperatures ranging from ; with optimum temperatures of . It prefers temperate seas with consistent currents. It has been found in waters with salinity as low as 6 parts per thousand. The relation between summer hypoxia and moon jellyfish distribution is prominent during the summer months of July and August where temperatures are high and dissolved oxygen (DO) is low. Of the three environmental conditions tested, bottom DO has the most significant effect on moon jellyfish abundance. Moon jellyfish abundance is the highest when bottom dissolved oxygen concentration is lower than 2.0 mg L−1. Moon jellyfish show a strong tolerance to low DO conditions, which is why their population is still relatively high during the summer. Generally, hypoxia causes species to move from the oxygen depleted zone, but this is not the case for the moon jellyfish. Furthermore, bell contract rate, which indicates moon jellyfish feeding activity, remains constant despite lower DO concentrations than normal. Other major fish predators that are also present in these coastal waters do not seem to show the same high tolerance to low DO concentrations that the moon jellyfish exhibit. The feeding and predatory performance of these fish significantly decreases when DO concentrations are so low. This allows for less competition between the moon jellyfish and other fish predators for zooplankton. Low DO concentrations in coastal waters such as Tokyo Bay in Japan and the Seto Inland Sea prove to be advantageous for the moon jellyfish in terms of feeding, growth, and survival. == Biology ==

The diet of Aurelia is similar to that of other jellyfish. They primarily feed on zooplankton. During July and August, it is observed that moon jellyfish aggregations of 250 individuals consumed an estimated 100% of the mesozooplankton biomass in the Seto Inland Sea. They may prey on or compete with commercially important fish and their larvae, as well as cause several issues for trawling boats when large aggregations occur, as they may clog and damage fishing nets as well as force fisherman to relocate. A 2020 study found that Aurelias body system is not significantly affected by artificial materials like microbeads, which can be found in cosmetic and personal care products. Aurelia aurita was able to recognize that microbeads were not food so there was not any physiological or histological harm. Aurelia have high proportions of polyunsaturated fatty acids compared to other prey types and are a source of vital nutrients for predators. Aurelia are known to be eaten by a wide variety of predators, including the ocean sunfish (Mola mola), the leatherback sea turtle (Dermochelys coriacea), the scyphomedusa Phacellophora camtschatica, and a very large hydromedusa (Aequorea victoria). Moon jellies are also fed upon by sea birds, which may be more interested in the amphipods and other small arthropods that frequent the bells of Aurelia, but in any case, birds do some substantial amount of damage to these jellyfish that often are found just at the surface of bays. Aurelia species have been suggested to have high mortality during the ephyra stage, which potentially affects the population size of the later medusa stage. While the main cause remains unknown, it is believed that they are consumed by one of three potential predatory filter-feeding sessile organisms: mussels, ascidians, and barnacles. Some metazoan parasites attack Aurelia, as well as most other species of jellyfish. There is an increasing size from starting stage planula to ephyra, from less than 1 mm in the planula stage, up to about 1 cm in ephyra stage, and then to several cm in diameter in the medusa stage. In 1997, it was summarized that seasonal reproduction leaves the gonads open to infection and degradation. == See also ==