Aurelia aurita
"Aurelia aurita" lives 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 although DO concentrations are lower than normal. 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. 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 the coastal waters such as the Tokyo Bay in Japan and Seto Inland Sea prove to be advantageous for the moon jellyfish in terms of feeding, growth, and survival.
Cotylorhiza tuberculata
Cotylorhiza tuberculata is a species of jellyfish, of the phylum Cnidaria, also known as the Mediterranean jelly or fried egg jellyfish. It is commonly found in the Mediterranean Sea, Aegean Sea, and Adriatic Sea. It can reach 40 cm in diameter and is usually less than 17 cm wide. It seems that this jellyfish's sting has very little or no effect on humans. The cnidarian’s smooth, elevated central dome is surrounded by a gutter-like ring. Its marginal lappets are elongated and subrectangular. Each moutharm bifurcates near its base and branches several times. In addition to some larger appendages, there are many short, club-shaped ones that bear disk-like ends.
"C. tuberculata" are the most common jellyfish of their entire order in the Mediterranean Sea. They experience an annual life cycle marked by summer population blooms, which is likely an adaptive result of the strong seasonal changes in their Mediterranean environment. Their phases of development are quite similar to that of their other jellyfish counterparts. "C. tuberculata"s four main stages of growth include the swimming larvae known as planulae, younger, sessile polyps called scyphistomae, the undeveloped young adult intermediates known as ephyrae, and the adult jellyfish forms, called medusas. In a given year, planulae are present from August to November, scyphistomae are present perennially, ephyrae can be seen from May to August, and medusa are prominent from July to November.