Jellyfish, also known as sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.
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 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.
Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic organisms that are relatively simple in structure with a diameter around 1mm. There are currently 120 known species, with more to be discovered. These species are grouped into three broad categories: O. bidentata, O. dichotoma, and O. geniculata. O. longissima was later accepted as a legitimate species, but taxonomy regarding the entire genus is debated over.
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.
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 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.
Carybdea is a genus of venomous box jellyfish within the family Carybdeidae that currently consists of a total of 8 species. This genus of jellyfish are often found in warm waters around the world in waters such as the Mediterranean Sea, the Pacific Ocean, and off the coast of Africa. Their sting can cause a range of effects depending on the species. These invertebrates will go through both sexual and asexual reproduction as they transform from a polyp to medusa. Carybdea have a box-shaped bell with four tentacles and eye-like sensory structures. There are distinct physical markings that differentiate many species within the genus. While Carybdea use their venom to act as predators, they are also preyed on by turtles and various fish. They feed on plankton, invertebrates, fish, and some crustaceans.
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.
Atolla wyvillei, also known as the Atolla jellyfish, Coronate medusa, and deep-sea jellyfish, 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.
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".
Aurelia is a genus of jellyfish that are commonly called moon jellies, which are in the class Scyphozoa. There are currently 25 accepted species and many that are still not formally described.
Sea anemones are a group of predatory marine invertebrates constituting the order Actiniaria. Because of their colourful appearance, they are named after the Anemone, a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia. As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.
Cassiopea andromeda is one of many cnidarian species called the upside-down jellyfish. It usually lives in intertidal sand or mudflats, shallow lagoons, and around mangroves. This jellyfish, often mistaken for a sea anemone, usually keeps its mouth facing upward. Its yellow-brown bell, which has white or pale streaks and spots, pulsates to run water through its arms for respiration and to gather food.
Narcomedusae is an order of hydrozoans in the subclass Trachylinae. Members of this order do not normally have a polyp stage. The medusa has a dome-shaped bell with thin sides. The tentacles are attached above the lobed margin of the bell with usually a gastric pouch above each. There are no bulbs on the tentacles and no radial canals. Narcomedusans are mostly inhabitants of the open sea and deep waters. They can be found in the Mediterranean in large numbers.
Vallentinia gabriellae, the hitch-hiking jellyfish, is a species of small, inconspicuous hydrozoan in the family Olindiidae. It is endemic to a few isolated parts of the western Atlantic Ocean. It is elusive in the wild but sometimes makes its appearance unexpectedly in seawater cultures of other organisms in the laboratory.
Gonionemus vertens, the clinging jellyfish, is a small species of hydrozoan in the family Olindiidae found in coastal regions throughout large parts of the Northern Hemisphere.
Tripedalia cystophora is a small species of box jellyfish in the family Tripedaliidae. It is native to the Caribbean Sea and the Central Indo-Pacific.
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.
Chiropsella bronzie is a species of box jellyfish. It is considered much less of a threat to humans than some of its relatives. The species was described in 2006, and is one of four species in the genus Chiropsella. Chiropsella bronzie can be found in shallow waters off the coast of Queensland, Australia.
Tripedalia is a genus within the family Tripedaliidae that is part of the box jellyfish, also known as the Cubozoa. There are only three known species within Tripedalia: T. cystophora, T. binata and T. maipoensis.
