The habitat of moon jellies encompasses oceanic coastal waters as well as warm tropical waters ranging in temperatures from 6-19 degrees Celsius. These jellies can live in waters with a salt content as low as 0.6%. Salt content and water temperature affect shape, size and reproductive strategies. They thrive best in waters with temperatures are above 17.5°C and salinity greater than 38.0%, largest. Moon jellies range in depth between the epipelagic zone and the mesopelagic zone (200 to 1,000 m). (Brekhman, et al., 2015; Browne, 1901; Conniff, 2000; El-Serehy and Al-Rasheid, 2011; FitzGeorge-Balfour, et al., 2013; Purcell, 2005; Schiariti, et al., 2015)
Moon jellies exhibit radial symmetry. They have transparent outer bells that range in diameter from 10 to 35 cm. Within the outer bell is another dome which has blue veins running through it; these veins are their gonads, which resemble horseshoe rings. These blue veins lead into elaborate coloring and patterns. Small tentacles, 1 to 5 cm long, radiate from the bells of moon jellies, out to their sides. Radiating from below the bell of moon jellies are four oral arms which contain stinging cells, or nematocysts, to aid in feeding by moving prey towards their gastric pouches. Small cilia radiate around their bells which also aid in feeding.
Moon jellies begin their lives as free floating planulae, which then morph into polyps – small sedentary organisms. Moon jelly polyps go through budding and create a number of disk-shaped segments. These disk segments detach and enter a free-floating stage, where they are called ephyrae. These ephyrae then develop into immature, mobile medusae before reaching sexual maturity. (Browne, 1901; Crowder, 1926; Fuchs, et al., 2014; Schiariti, et al., 2015)
Once mature, sexual medusae mate. Fertilized eggs, called planulae, spend 10 days on average swimming around using small cilia before finding and attaching themselves to hard surfaces, becoming polyps. Polyps are benthic, bottom dwelling organisms. Once attached, these moon jelly polyps use asexual reproduction (budding) to create daughter polyps. These polyps then mature into strobilae, which are sacs of undeveloped jellyfish. In order for these strobilae to produce an adult, or medusa, strobulation must occur. This strobulation is the development of ephyrae from the strobilae. Once ephyrae are developed, they leave the strobilae, making room for other sacs to develop. These ephyrae then mature into juvenile medusae before maturing again to become sexually mature medusae. The time it takes for maturation from the ephyra to the mature medusa stage depends on environmental cues such as temperature, salinity and food. Under suitable conditions, this process takes 4 to 6 months. (El-Serehy and Al-Rasheid, 2011; Lucas, 2001)
Moon jellies elicit no courtship behavior, and there is no social structure that affects mating systems. Male jellyfish in their mature medusa stage release sperm filaments into the water surrounding female jellies. These filaments ride water currents, entering the gastric pouches of nearby females. These animals also reproduce asexually when they are in their polyp stage. (Lucas, 2001)
The general mating behavior and reproductive system of moon jellies starts when sexually mature (4 to 12 months old) males release sperm filaments into the water surrounding females. Female mon jellies then use their cilia to internalize the sperm into their gastric pouches. These gastric pouches contain eggs which, once fertilized, are released into the water. Moon jellyfish breed year-round, with mating intervals depending on environmental conditions. Moon jellyfish reproduction occurs when medusae reach sexual maturity, generally a range of 2 to 3 months during summer and autumn. They also reproduce asexually while in their sessile polyp stage. (Brekhman, et al., 2015; El-Serehy and Al-Rasheid, 2011; Lucas, 2001; Schiariti, et al., 2015)
There is no reported data on parental involvement.
Moon jellies range widely on longevity and lifespan based on environmental factors. In most cases, strobilation of the ephyrae occurs between winter and spring, but has also been observed throughout the rest of the year. Moon jellyfish have an average lifespan of approximately 8 to 12 months, allowing for slow growth during colder months, and faster growth during spring. After reaching sexual maturity, medusae shrink, release gametes, and typically die in the later spring and early summer season. Maximum ages in the wild are reported as 2 years.
In aquarium settings, lifespans are as short as 6 months, but polyps have been recorded as living up to 25 years before maturing. (Lucas, 2001)
Moon jellyfish elicit feeding behaviors based on availability of prey and oxygen levels. When oxygen levels are low, moon jellies engage in nutritional loading, and flourish when prey are abundant. Moon jellyfish spend their early life as a sedimentary polyp before becoming a motile medusa. Medusae use pulsate water through their bells to stay horizontal, close to the surface of the water. This allows for a further tentacle spread for prey capture. Large blooms of jellyfish are found worldwide based on temperature, prey availability, oxygen content and salt content. (Lucas, 2001; McHenry and Jed, 2003; Shoji, et al., 2005)
Research into the communication of moon jellyfish is limited. It is hypothesized that moon jellyfish communicate via chemicals secreted into the water. Some jellyfish have ocelli, which are structures located on the bell that are used to detected changes in light and allow for vertical diurnal migration to avoid predation and to help with active foraging behavior. Another sensory organ is the rhopalium; many of these are located around the rim of the bell on a jellyfish. Rhopalia contain sensory organs called statocysts, these structures are used to maintain balance and determine depth and as well as sense gravity, helping jellyfish stay upright. Jellyfish also use touch to capture prey using stinger cells called cnidocytes or nematocysts. (Graham and Kroutil, 2001; Graham, et al., 2001; Jacobs, et al., 2007)
As carnivorous organisms, moon jellies are known to feed on most organisms small enough to become entangled on their bells or in their tentacles. These include plankton, copepods, mollusks, fish eggs and smaller jellyfish. Once entangled, moon jellies uses their oral arms to move their prey towards their stomachs, located under the their bells. (Browne, 1901; Crowder, 1926; FitzGeorge-Balfour, et al., 2013; Graham and Kroutil, 2001; Lucas, 2001)
Moon jellyfish are consumed by birds in the order (Charadriiformes), other jellyfish, chum salmon (Oncorhynchus keta), butterfish (Peprilus) in the family Stromateidae, sunfish, and leatherback sea turtles (Dermochelys coriacea).
Moon jellies have anti-predator adaptations, including small stinging cells on their oral arms. These stinging cells are called cnidoblasts or nematocysts, used for capturing prey and warding off predators. Another adaptation that moon jellies have is their translucent coloring, which makes them difficult to detect from below or above. (Conniff, 2000; Gold, et al., 2015; Jachowski, 1963)
Moon jellyfish can be a harmful species when entering a new environment. Once they arrive, if resources are sufficient, jellyfish populations expand quickly, consuming plankton, adult fish and fish larvae. They also compete with fish for resources. They are known to negatively impact fisheries and plankton blooms. They are a generalist feeder, using cilia and tentacles to consume organisms that they encounter. Spider crabs (Libinia dubia) and amphipods (Hyperia galba) are moon jely parasites. They have been found in their bells as well as attached to their tentacles. They parasitize medusae by eating their prey and the medusae themselves. (Jachowski, 1963; Lucas, 2001)
These jellyfish are being researched for uses as food, medicine and drugs. A fluorescent protein was developed from jellyfish, which was beneficial to biotechnology. (Brotz, et al., 2012)
Moon jellyfish cause economic problems for humans. Large jellyfish populations can harm fisheries, as well as compete for food with humans. They also clog up power plant water intakes, as well as desalination plants. Moon jellies also affect tourism by stinging humans that are swimming. (Brotz, et al., 2012; Lucas, 2001)
Jellyfish are an invasive species that have large population blooms and are currently not on any international or federal lists. They have not been evaluated by the IUCN Red List. There are efforts being taken to remove jellyfish from non-native areas as well as from power-plants and fisheries using trawlers and nets. (Brotz, et al., 2012)
ross tombs (author), Radford University - Fall 2015, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Jacob Vaught (editor), Radford University, Galen Burrell (editor), Special Projects.
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.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
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.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
found in the oriental region of the world. In other words, India and southeast Asia.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
an animal that mainly eats plankton
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).
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
uses sight to communicate
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