User:ColbyRee/Phacellophora camtschatica

Cotylorhiza tuberculata. A jellyfish also commonly known as the fried egg jellyfish.

Phacellophora camtschatica, commonly known as the fried egg jellyfish or egg-yolk jellyfish, is a very large jellyfish in the family Phacellophoridae. This species can be easily identified by the yellow coloration in the center of its body which closely resembles an egg yolk, hence how it got its common name. Some individuals can have a bell close to 60 cm (2 ft) in diameter, and most individuals have 16 clusters of up to a few dozen tentacles, each up to 6 m (20 ft) long. A smaller jellyfish, Cotylorhiza tuberculata, typically found in warmer water, particularly in the Mediterranean Sea, is also popularly called a fried egg jellyfish. Also, Phacellophora is sometimes confused with the Lion's mane jellyfish (Cyanea capillata).

It feeds primarily by collecting medusae and plankton with its tentacles, and bringing them into its mouth for digestion. It is capable of only limited motion, and mostly drifts with the current, even when swimming. This species and most of its relatives in the cnidaria phylum often use suspension feeding as their main food gathering strategy.

The body of this jellyfish doesn't contain any respiratory, circulatory, or excretory systems. Instead, it uses its large surface area to accomplish these things. Also, this species (and all others in the phylum cnidaria) lack a mesoderm and instead uses mesolgea. Therefore, there are not three true tissue layers, in turn making this species (and all other cnidarians) diploblastic not triploblastic.

The reproduction and life cycle of this jellyfish has been well documented. It mostly follows the the same life cycle as other members in the class scyphozoa. It alternates between a polyp form that reproduces asexually and a medusa form that reproduces sexually. Additionally, this jellyfish is found throughout the word, but is most commonly found in the northern pacific ocean.

Taxonomy and systematics

This jellyfish is a representative of the family Phacellophoridae in the class of scyphozoa. However, it used to be a part of the family ulmaridae but was recently changed when a study found that juveniles did not match characteristics of the families Cyaneidae or Ulmaridae. Instead, it appeared to be an intermediate between the two families and thus a new family was created specifically for this species.

Feeding

Phacellophora camtschatica feeds mostly on smaller jellyfish and other gelatinous zooplankton, which become ensnared in the tentacles. Tentacles contain nematocysts, which help in prey capture. These structures also provide defense against predation. Food that is caught in the tentacles is then covered in mucous, then these tentacles are brought to the mouth by oral lobes. Food is then digested by digestive enzymes in the gastrovascular cavity. Broken down food is then distributed throughout the jellyfish by ciliated action.

Phacellophora camtschatica primarily feeds on Aurelia aurita, Aurelia labiata, Aequorea victoria and Pleurobrachia bachei. However, these species have been known to host symbionts that will transfer onto P. camtschatica when the host is consumed. This is possible because the sting of this jellyfish is weak therefore allowing many symbionts/parasites including small crustaceans like larval crabs (Cancer gracilis) and some Amphipoda (Hyperia medusarum) to regularly ride on its bell and even steal food from its oral arms and tentacles. The crab begins its association with the jellyfish as a megalopa, where the crab consumes the tentacles and uses the jelly as a platform to eat small planktonic prey from the water and from the surfaces of the host. Later, the crab then develops into an instar and continues to ingest prey captured by the jellyfish but shifts much of its diet to include H. medusarum, thus reducing the overall parasitic impact on the host.

Body systems

Phacellophora camtschatica does not have respiratory organs such as gills, lungs or trachea. Instead, it respires by diffusing oxygen from water through the thin membrane covering its body. Within the gastrovascular cavity, low oxygenated water can be expelled through the mouth and high oxygenated water can be distributed by ciliated action, thus increasing the diffusion of oxygen into the cells. The large surface area to volume ratio helps to diffuse more oxygen and nutrients into the cells.

The basic body plan consists of several parts. Although, this animal lacks respiratory, excretory, and circulatory systems because of the high surface area to volume ratio. Food travels through the muscular manubrium while the radial canals help disperse the food. The deep fried jelly and all other members of the phylum cnidaria are diploblastic. This is due to a lack of a mesoderm, which in this phylum is replaced with mesoglea. The tissue layers of this species is a middle layer of mesoglea, a gastrodervascular cavity with a gastrodermis, and an epidermis. Additionally, there is a nerve net that is responsible for contractions in swimming muscles and responses while feeding.

Life Cycle

The life cycle of this jellyfish is well known, because it is kept in culture at the Monterey Bay Aquarium. During its life cycle, it alternates between a benthic stage attached to rocks and piers that reproduces asexually and a planktonic stage that reproduces sexually in the water column; both males and females occur in the plankton form.

The general life-cycle of this species is that fertilized eggs develop into ciliated planulae that swim, settle, and metamorphose into scyphistomae (polyps). Polyps then undergo 2-, 4-, 8-, and 16-tentacled stages of development before reaching the mature complement of 30–44 tentacles. Later, the polyps reproduce asexually by side budding and strobilating which releases ephyrae that grow into mature medusae. It takes about 9 months for an ephyra to become a sexually mature medusa under laboratory conditions.The cycle then repeats all over again.

Distribution

This cool-water species can be found in many parts of the world's oceans. Although, the abundance of this species in open marine waters is relatively low. Though, it can be rather widespread in some parts of the Sea of Japan and the Sea of Okhotsk, especially near the shore where it was found to dominate in the southern part of this area. But, most areas were predominantly composed of solitary individuals. It was also found in the western and eastern Bering Sea. Additionally, it constituted a noticeable proportion of jellyfish biomass in waters of the northern California Current.

In a study conducted in 2011, the egg-yolk jelly was found to aggregate mostly over deep basins, whereas in shallow areas a significant quantity of this species was found only off West Kamchatka, This is in stark contrast to the other members of the Ulmaridae family which prefer shallow water. This preference could be related to the bell size of the individual which ranges from 5-59 cm. This bell size likely allows the jellyfish to swim in deeper waters.

Also, jellyfish populations (including the egg-yolk jelly) are on the rise in degraded areas as a result of increased tolerance to detrimental factors. Additionally, jellyfish play a large role in the food web and can serve as indicators of ecosystem structure and function; The larger the jellyfish population, the greater the impact on ecosystem services.

Furthermore, this species has been known to dive into deep water areas with little oxygen (hypoxia zone) when competition is high. Hypoxia generally causes species to move from the oxygen depleted zone, but this is not the case for the deep-fried jellyfish. Instead, this species can survive for several hours at a time in this area, typically during the day. And, with the belief that hypoxia regions will continue to grow, the deep-fried jellyfish could thrive.