Stellamedusa is a genus of jellyfish. The genus is monotypic with a single species recognized, Stellamedusa ventana.
The species was first described in the Journal of the Marine Biological Association in 2004 by Kevin Raskoff and George Matsumoto of the Monterey Bay Aquarium Research Institute. As of February 2004, seven specimens have been observed, five off the California coast in Monterey Bay and two in the Gulf of California. Unlike most medusae, they lack marginal tentacles. Specimens so far found reach almost 10cm in diameter, which is large for a scyphomedusa. The bell is blue-white in colour. The exumbrella is white, and this and the four oral arms are covered with large nematocyst-laden projections filled with stinging cells, enabling the jelly to capture food items of a variety of sizes; it seems to prefer large prey, up to half its size, which is unusual in jellies that capture prey with their bells rather than with tentacles. The bumpy appearance that the stinging cells give to the jelly led to its common name. The species name comes from the remotely operated vehicle (ROV) Ventana, a deep-diving robotsubmarine that first recorded the jelly on video in 1990.
Stellamedusa ventana has so far been observed only at mesopelagic depths, i.e. between 150 and 550 meters. At these depths, sunlight does not penetrate, but there is still a reasonable amount of oxygen. Many species of jellyfishes live at this level, and it is likely that S. ventana feeds primarily on other jellies. Another large jellyfish discovered by the same researchers is Tiburonia granrojo.
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larva that disperse widely and enter a sedentary polyp phase before reaching sexual maturity.
Box jellyfish are cnidarian invertebrates distinguished by their box-like body. Some species of box jellyfish produce potent venom delivered by contact with their tentacles. Stings from some species, including Chironex fleckeri, Carukia barnesi, Malo kingi, and a few others, are extremely painful and often fatal to humans.
Aurelia aurita is a widely studied species of the genus Aurelia. All species in the genus are very similar, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus. The most common method used to identify the species consists of selecting a jellyfish from a harbour using a device, usually a drinking glass and then photographing the subject. This means that they can be released in to the harbour shortly afterwards and return to their natural habitat.
The Atlantic sea nettle, also known as the East Coast sea nettle or US Atlantic sea nettle, is a species of jellyfish that inhabits the Atlantic coast of the United States. Historically it was confused with several Chrysaora species, resulting in incorrect reports of C. quinquecirrha from other parts of the Atlantic and other oceans. Most recently, C. chesapeakei of estuaries on the Atlantic coast of the United States, as well as the Gulf of Mexico, was only fully recognized as separate from C. quinquecirrha in 2017. It is smaller than the Pacific sea nettle, and has more variable coloration, but is typically pale, pinkish or yellowish, often with radiating more deeply colored stripes on the exumbrella, especially near the margin.
The lion's mane jellyfish, also known as the giant jellyfish, arctic red jellyfish, or the hair jelly, is one of the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common in the English Channel, Irish Sea, North Sea, and in western Scandinavian waters south to Kattegat and Øresund. It may also drift into the southwestern part of the Baltic Sea. Similar jellyfish – which may be the same species – are known to inhabit seas near Australia and New Zealand. The largest recorded specimen was measured off the coast of Massachusetts in 1870 and had a bell with a diameter of 210 centimetres and tentacles around 36.6 m (120 ft) long. Lion's mane jellyfish have been observed below 42°N latitude for some time in the larger bays of the east coast of the United States.
Aequorea victoria, also sometimes called the crystal jelly, is a bioluminescent hydrozoan jellyfish, or hydromedusa, that is found off the west coast of North America.
Chironex fleckeri, commonly known as the Australian box jelly, and nicknamed the sea wasp, is a species of extremely venomous box jellyfish found in coastal waters from northern Australia and New Guinea to Malaysia, the Philippines and Vietnam. It has been described as "the most lethal jellyfish in the world", with at least 64 known deaths in Australia from 1884 to 2021.
Craspedacusta sowerbii or peach blossom jellyfish is a species of freshwater hydrozoan jellyfish, or hydromedusa cnidarian. Hydromedusan jellyfish differ from scyphozoan jellyfish because they have a muscular, shelf-like structure called a velum on the ventral surface, attached to the bell margin. Originally from the Yangtze basin in China, C. sowerbii is an invasive species now found throughout the world in bodies of fresh water.
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, P. camtschatica is sometimes confused with the Lion's mane jellyfish.
Tiburonia is a genus of jellyfish in the family Ulmaridae. It was reported in 2003, following the discovery of its only species yet identified, Tiburonia granrojo. It was discovered by a crew from MBARI led by George Matsumoto. Pieces of the medusae were collected for morphological analysis, which eventually led to sequencing and taxonomic identification. The discovery of this organism led to not only a new species, but a new subfamily of Ulmaridae, called Tiburoniinae. Its genus was named Tiburonia after the ROV the crew were using, called Tiburon, meaning "shark" in Spanish. Because of this ROVs distinct maneuverability, all angles of the organisms were able to be observed, which is particularly important to the study of gelatinous pelagic invertebrates. Its species name was originally to be called "big ugly", but Kirsten Matsumoto raised objections to this name, and renamed it granrojo, meaning "big red" in Spanish.
Turritopsis dohrnii, also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary individual. Others include the jellyfish Laodicea undulata and species of the genus Aurelia.
The spotted jelly, lagoon jelly, golden medusa, or Papuan jellyfish, is a species of jellyfish from the Indo-Pacific oceans. Like corals, sea anemones, and other sea jellies, it belongs to the phylum Cnidaria. Mastigias papua is one of the numerous marine animals living in symbiosis with zooxanthellae, a photosynthetic alga.
The black sea nettle, sometimes informally known as the black jellyfish or sarlacc jellyfish, is a species of jellyfish that can be found in the waters of the Pacific Ocean. Its range is thought to be from Monterey Bay in the north, down to southern Baja California and Mexico, though there are reports of sightings as far north as British Columbia.
Chrysaora colorata (Russell), commonly known as the purple-striped jelly, is a species of jellyfish that exists primarily off the coast of California from Bodega Bay to San Diego. The bell (body) of the jellyfish is up to 70 cm (2.3 ft) in diameter, typically with a radial pattern of stripes. The tentacles vary with the age of the individual, consisting typically of eight marginal long dark arms, and four central frilly oral arms. It is closely studied by scientists due to not much being known about their eating habits.
The flower hat jelly is a species of hydromedusa in the hydrozoan family Olindiidae. Although they look like a jellyfish, they actually belong in the class Hydrozoa, while true jellyfish belong in class Scyphozoa. Flower hat jellies occur in the northwestern Pacific off central and southern Japan, and South Korea's Jeju Island.. The adult form of the flower hat jelly only lives a few months and is typically seen from December to July, with peaks in April and May. During the day they rest on the bottom, often among rocks or algae, but at night they float up to hunt for their prey, typically small fish.
The jelly blubber, also known as the blue blubber jellyfish, is a species of jellyfish from coastal regions in the Indo-Pacific. It is the most commonly encountered jellyfish along the Australian eastern coast and large swarms sometimes appear in estuarine waters.
Cydippida is an order of comb jellies. They are distinguished from other comb jellies by their spherical or oval bodies, and the fact their tentacles are branched, and can be retracted into pouches on either side of the pharynx. The order is not monophyletic, that is, more than one common ancestor is believed to exist.
Thalassocalyce is a genus of ctenophore, or comb jellies, known from the California Coast, Gulf of Mexico, and west north Atlantic. It is represented by a single species, Thalassocalyce inconstans, which is the only species in the family Thalassocalycidae and the order Thalassocalycida. T. inconstans is a pelagic ctenophore typically occurring in upper-mesopelagic depths, but has been observed at depths up to 3,500 m in Monterey Canyon.
Bougainvillia superciliaris is a marine invertebrate, a species of athecate hydroid. It belongs to the Bougainvillidae family. It can be confused with Rathkea octopunctata, but differs from it in four bundles of tentacles of the outer circle.
Desmonema is a genus of jellyfish under the Cyaneidae family found in colder waters near the Antarctic region and off of the coast of Argentina. They have a bell diameter that can extend over 1 meter and wide tentacles that are grouped together in clusters. They share similar anatomical and physiological structures to the genus Cyanea. Their sophisticated structures like the thick tentacles, sensory systems, and gastrovascular system allow Desmonema to easily capture and extracellularly digest their prey. In recent years, Desmonema were reported to have a commensal relationship with fishes under the Trachurus genus and a parasitic relationship with specimens of the Hyperia genus.
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