Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, including jellyfish, hydroids, sea anemone, corals and some of the smallest marine parasites. Their distinguishing features are a decentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick.
Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.
The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish.
Ctenophora comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming, and they are the largest animals to swim with the help of cilia.
Aurelia aurita is a species of the family Ulmaridae. 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.
Coelenterata is a term encompassing the animal phyla Cnidaria and Ctenophora. The name comes from Ancient Greek κοῖλος (koîlos) 'hollow', and ἔντερον (énteron) 'intestine', referring to the hollow body cavity common to these two phyla. They have very simple tissue organization, with only two layers of cells, and radial symmetry. Some examples are corals, which are typically colonial, and hydrae, jellyfish, and sea anemones, which are solitary. Coelenterata lack a specialized circulatory system relying instead on diffusion across the tissue layers.
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 Indonesia, Cambodia, Malaysia and Singapore, 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.
Crown jellyfishes are the six families of true jellyfish that belong to the order Coronatae. They are distinguished from other jellyfish by the presence of a deep groove running around the umbrella, giving them the crown shape from which they take their name. Many of the species in the order inhabit deep sea environments.
Pelagia noctiluca is a jellyfish in the family Pelagiidae and the only currently recognized species in the genus Pelagia. It is typically known in English as the mauve stinger, but other common names are purple-striped jelly, purple stinger, purple people eater, purple jellyfish, luminous jellyfish and night-light jellyfish. In Greek, pelagia means "(she) of the sea", from pelagos "sea, open sea"; in Latin noctiluca is the combining form of nox, "night"", and lux, "light"; thus, Pelagia noctiluca can be described as a marine organism with the ability to glow in the dark (bioluminescence). It is found worldwide in tropical and warm temperate seas, although it is suspected that records outside the North Atlantic region, which includes the Mediterranean and Gulf of Mexico, represent closely related but currently unrecognized species.
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, George Matsumoto's wife, raised objections to this name, and renamed it granrojo, meaning "big red" in Spanish, leading to its English-language name, the Big Red Jellyfish.
Atolla wyvillei, also known as the Atolla jellyfish or Coronate medusa, is a species of deep-sea crown jellyfish. It lives in oceans around the world. Like many species of mid-water animals, it is deep red in color. This species was named in honor of Sir Charles Wyville Thomson, chief scientist on the Challenger expedition.
Atolla is a genus of crown jellyfish in the order Coronatae. The genus Atolla was originally proposed by Haeckel in 1880 and elevated to the monotypic family level, as Atollidae by Henry Bigelow in 1913. The six known species inhabit the mesopelagic zone. The medusae possess multiple lobes called lappets at the bell margin. Medusae also have eight tentacles, alternating with eight rhopalia, and twice as many lappets occur as tentacles.
Chrysaora hysoscella, the compass jellyfish, is a common species of jellyfish that inhabits coastal waters in temperate regions of the northeastern Atlantic Ocean, including the North Sea and Mediterranean Sea. In the past it was also recorded in the southeastern Atlantic, including South Africa, but this was caused by confusion with close relatives; C. africana, C. fulgida and an undescribed species tentatively referred to as "C. agulhensis".
Cyanea is a genus of jellyfish, primarily found in northern waters of the Atlantic and Pacific Oceans and southern Pacific waters of Australia and New Zealand, there are also several boreal, polar, tropical and sub-tropical species. Commonly found in and associated with rivers and fjords. The same genus name has been given to a genus of plants of the Hawaiian lobelioids, an example of a parahomonym.
The helmet jellyfish, sometimes called the merchant-cap, is a luminescent, red-colored jellyfish of the deep sea, belonging to the order Coronatae of the phylum Cnidaria. It is the only species in the monotypic genus Periphylla and is one of the rare examples in Scyphozoa which life-cycle lacks a polyp stage. This species is photophobic and inhabits deeper parts of the oceans to avoid light. It may be found at the surface on dark nights.
Carybdea marsupialis is a venomous species of box jellyfish, in the small family Carybdeidae within the class Cubozoa.
The thimble jellyfish is a species of cnidarian found in the warm West Atlantic Ocean, including the Caribbean. It is a tiny jellyfish with a straight-sided, flat-topped bell. This jellyfish is the most common cause of seabather's eruption, a reaction caused by the injection of juvenile jellyfish nematocysts into human skin.
Spirularia is an order of marine Cnidarians, tube-dwelling anemones, in the subclass Ceriantharia. It is one of the two orders making up Ceriantharia and includes two families, Botrucnidiferidae and Cerianthidae, and around 99 species. The two orders differ in the makeup of their cnidome, the relative sizes of the oral discs and the shape and structure of the mesenteries.
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. The genus name derives from the Ancient Greek desmós (δεσμός), meaning "bond", and nêma (νῆμᾰ), meaning "thread".
Cyanea fulva, the Atlantic lion's mane jellyfish, is a species of jellyfish found along the Mid-Atlantic coastal region of the United States. C. fulva are commonly noted as being about two inches in diameter and smaller than C. capillata, however, larger than C. versicolor, a co-occurring close species. One distinctive feature present in mature C. fulva populations is their four mouth-part tentacles, containing a cinnamon color with the center of the main cavity being darker. At a young age, these jellyfish can have three appendages but often gain a fourth at more developed life cycle stages. C. fulva are also known for having less folds compared to C. arctica but more folds compared to C. versicolor. These folds are described as being remarkably thin and deciduous.
