Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water and marine environments, including jellyfish, hydroids, sea anemones, 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. Cnidarians are also some of the few animals that can reproduce both sexually and asexually.
Anthozoa is a class of marine invertebrates which includes sessile cnidarians such as the sea anemones, stony corals, soft corals and sea pens. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as planktons. The basic unit of the adult is the polyp; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles. Sea anemones are mostly solitary, but the majority of corals are colonial, being formed by the budding of new polyps from an original, founding individual. Colonies are strengthened by calcium carbonate and other materials and take various massive, plate-like, bushy or leafy forms.
Renilla reniformis, the sea pansy, is a species of soft coral in the family Renillidae. It is native to warm continental shelf waters of the Western Hemisphere. It is frequently found washed ashore on North East Florida beaches following northeasterly winds or rough surf conditions. It also can often be found living intertidally completely buried in the sand. Its predator is the striped sea slug, Armina tigrina.
Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Cubozoa, and possibly the parasitic Polypodiozoa. Medusozoans are distinguished by having a medusa stage in their often complex life cycle, a medusa typically being an umbrella-shaped body with stinging tentacles around the edge. With the exception of some Hydrozoa, all are called jellyfish in their free-swimming medusa phase.
Staurozoa is a class of Medusozoa. It has one extant order: Stauromedusae with a total of 50 known species. A fossil group called Conulariida has been proposed as a second order, although this is highly speculative. The extinct order is largely unknown and described as a possibly cnidarian clade of marine life with shell-like structures, the Conulariida. Staurozoans are small animals that live in marine environments, usually attached to seaweeds, rocks, or gravel. They have a large antitropical distribution, a majority found in boreal or polar, near-shore, and shallow waters. Few staurozoans are found in warmer tropical and subtropical water environments of the Atlantic, Indian, and Pacific Ocean basins, but most are known from the Northern Hemisphere. Over the years the number of discovered species has increased, with an estimated 50 species currently recognized. Information on Staurozoa is sparse, and it is one of the least studied groups within Cnidaria. While often neglected, correctly recognizing the characteristics of this class is crucial for understanding cnidarian evolution.
Alcyonacea are an order of sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Whilst not in a strict taxonomic sense, Alcyonacea are commonly known as soft corals. The term "soft coral" generally applies to organisms in the two orders Pennatulacea and Alcyonacea with their polyps embedded within a fleshy mass of coenenchymal tissue. Consequently, the term "gorgonian coral" is commonly handed to multiple species in the order Alcyonacea that produce a mineralized skeletal axis composed of calcite and the proteinaceous material gorgonin only and corresponds to only one of several families within the formally accepted taxon Gorgoniidae (Scleractinia). These can be found in order Malacalcyonacea (taxonomic synonyms of include : Alcyoniina, Holaxonia, Protoalcyonaria, Scleraxonia, and Stolonifera.
Octocorallia is a class of Anthozoa comprising over 3,000 species of marine organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians within three orders: Alcyonacea, Helioporacea, and Pennatulacea. These organisms have an internal skeleton secreted by mesoglea and polyps with eight tentacles and eight mesentaries. As with all cnidarians these organisms have a complex life cycle including a motile phase when they are considered plankton and later characteristic sessile phase.
The habitat of deep-water corals, also known as cold-water corals, extends to deeper, darker parts of the oceans than tropical corals, ranging from near the surface to the abyss, beyond 2,000 metres (6,600 ft) where water temperatures may be as cold as 4 °C (39 °F). Deep-water corals belong to the Phylum Cnidaria and are most often stony corals, but also include black and thorny corals and soft corals including the Gorgonians. Like tropical corals, they provide habitat to other species, but deep-water corals do not require zooxanthellae to survive.
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.
Leptogorgia virgulata, commonly known as the sea whip or colorful sea whip, is a species of soft coral in the family Gorgoniidae.
Primnoa(Lamororux, 1812) also known as red tree coral, is a genus of soft corals and the type genus of the family Primnoidae (Milne Edwards, 1857). They are sessile, benthic cnidarians that can be found in the North Pacific, North Atlantic, and Subantarctic South Pacific, and its members often play a vital ecological role as keystone species within their environment as a habitat and refuge for the megafauna that also inhabit those regions. This, in combination with their slow growth, makes the increasing disturbance to their habitats caused by fishing activities particularly impactful and difficult to recover from.
Echinoptilidae is a family of sea pens, a member of the subclass Octocorallia in the phylum Cnidaria.
Virgulariidae is a family of sea pens, a member of the subclass Octocorallia in the phylum Cnidaria.
Paramuricea clavata, the violescent sea-whip, is a species of colonial soft coral in the family Plexauridae. It is found in shallow seas of the north-eastern Atlantic Ocean and the north-western Mediterranean Sea as well as Ionian Sea. This species was first described by the French naturalist Antoine Risso in 1826.
Taiaroa is a genus of deep-water, solitary marine octocorals in the family Taiaroidae. Taiaroa is monotypic in the family Taiaroidae and contains a single species, Taiaroa tauhou. The species was first described by the marine zoologists Frederick M. Bayer and Katherine Margaret Muzik in 1976. The scientific name derives from "Taiaroa", the submarine canyon off New Zealand in which the first specimens were found and "tauhou", the Maori word for "strange".
Pseudoplexaura porosa, commonly known as the porous sea rod or the porous false plexaura, is a species of gorgonian-type colonial octocoral in the family Plexauridae. It is native to the Caribbean Sea and the Gulf of Mexico.
Ptilosarcus gurneyi, the orange sea pen or fleshy sea pen, is a species of sea pen in the family Pennatulidae. It is native to the northeastern Pacific Ocean where it lives in deep water anchored by its base in sand or mud. It has received its common name because of its resemblance to a quill in a bottle of ink.
Swiftia comauensis species of gorgonian-type octocoral in the family Plexauridae, only found in the Comau fiords of Huinay in the Hualaihué province of the region of Los Lagos, Chile.
The slender sea pen is a species of sea pen in the family Virgulariidae, occurring throughout the Mediterranean and Western Europe, with some colonies being found on islands in the Mid-Atlantic.
Briareum asbestinum, commonly known as the corky sea finger, is a species of a soft coral in the family Briareidae. It inhabits coral reefs and rocky bottoms in the Caribbean, Bahamas, and Florida, often growing to 30 cm at depths of one to 40 metres.
