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Anthozoans
Anthozoa is one of the three subphyla of Cnidaria, along with Medusozoa and Endocnidozoa. It includes sessile marine invertebrates and invertebrates of brackish water, such as sea anemones, stony corals, soft corals and sea pens. Almost all adult anthozoans are attached to the seabed, while their larvae can disperse as plankton. The basic unit of the adult is the polyp, an individual animal consisting 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 of stony corals are strengthened by mainly aragonite and other materials, and can take various massive, plate-like, bushy or leafy forms. Members of Anthozoa possess cnidocytes, a feature shared among other cnidarians such as the jellyfish, box jellies and parasitic Myxozoa and Polypodiozoa. The two classes of Anthozoa are class Hex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medusozoa
Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Box jellyfish, Cubozoa, and possibly the parasitic Polypodium (animal), 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 (and Polypodiozoa), all are called jellyfish in their free-swimming Jellyfish#Life history and behavior, medusa phase. Evolution The phylum Cnidaria is widely accepted as being Monophyly, monophyletic and consisting of two clades, Anthozoa and Medusozoa. Anthozoa includes the Class (biology), classes Hexacorallia, the hard corals, and Octocorallia, the soft corals, as well as Tube-dwelling anemone, Ceriantharia, the tube-dwelling anemones. There is strong support for this group having been the first to branch off from the ancestral line. Meduso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cnidaria
Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, sea anemones, corals and some of the smallest marine parasites. Their distinguishing features are an uncentralized 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 (biology), cell thick. Cnidarians are also some of the few animals that can reproduce both sexually and asexually. Cnidarians mostly have two basic body forms: swimming medusa (biology), medusae and sessility (motility), sessile polyp (zoology), polyps, both of which are radially symmetrical with mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ediacaran
The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last period of the Proterozoic geologic eon, Eon as well as the last of the so-called "Precambrian supereon", before the beginning of the subsequent Cambrian Period marks the start of the Phanerozoic Eon, where recognizable fossil evidence of life becomes common. The Ediacaran Period is named after the Ediacara Hills of South Australia, where trace fossils of a diverse community of previously unrecognized lifeforms (later named the Ediacaran biota) were first discovered by geologist Reg Sprigg in 1946. Its status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years. Although the period took namesake from the Ediacara Hills ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seabed
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of the ocean is very deep, where the seabed is known as the abyssal plain. Seafloor spreading creates mid-ocean ridges along the center line of major ocean basins, where the seabed is slightly shallower than the surrounding abyssal plain. From the abyssal plain, the seabed slopes upward toward the continents and becomes, in order from deep to shallow, the continental rise, Continental slope, slope, and Continental shelf, shelf. The depth within the seabed itself, such as the depth down through a sediment core, is known as the "depth below seafloor". The ecological environment of the seabed and the deepest waters are collectively known, as a habitat for creatures, as the "benthos". Most of the seabed throughout the world's oceans is covered in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class (biology)
In biological classification, class () is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are domain, kingdom, phylum, order, family, genus, and species, with class ranking between phylum and order. History The class as a distinct rank of biological classification having its own distinctive name – and not just called a ''top-level genus'' ''(genus summum)'' – was first introduced by French botanist Joseph Pitton de Tournefort in the classification of plants that appeared in his '' Eléments de botanique'' of 1694. Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct ''grade'' of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct ''type'' of construction, whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypodiozoa
''Polypodium'' is a genus of cnidarians that parasitizes in the eggs of sturgeon and similar fishes (Acipenseridae and Polyodontidae). It is one of few animals that lives inside the cells of other animals. ''Polypodium hydriforme'' is the only species of this monotypic genus. The parent family (Polypodiidae), order (Polypodiidea) and class (Polypodiozoa) are also monotypic. Taxonomy Unusual characteristics have led to much controversy regarding the phylogenetic position of ''Polypodium'' within metazoans. ''Polypodium'' has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. Molecular phylogenetic studies using 18S rDNA sequence data temporarily challenged this interpretation, by finding that ''Polypodium'' is a close relative to myxozoans and suggesting that together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, these results were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myxozoa
Myxozoa (etymology: Greek: μύξα ''myxa'' "slime" or "mucus" + thematic vowel o + ζῷον ''zoon'' "animal") is a subphylum of aquatic cnidarian animals – all obligate parasites. It contains the smallest animals ever known to have lived. Over 2,180 species have been described and some estimates have suggested at least 30,000 undiscovered species. Many have a two-host lifecycle, involving a fish and an annelid worm or a bryozoan. The average size of a myxosporean spore usually ranges from 10 μm to 20 μm, whereas that of a malacosporean (a subclade of the Myxozoa) spore can be up to 2 mm. Myxozoans can live in both freshwater and marine habitats. Myxozoans are highly derived cnidarians that have undergone dramatic evolution from a free swimming, self-sufficient jellyfish-like creature into their current form of obligate parasites composed of very few cells. As myxozoans evolved into microscopic parasites, they lost many genes responsible for multice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Box Jellyfish
Box jellyfish (class Cubozoa) are cnidarian invertebrates distinguished by their box-like (i.e., cube-shaped) 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. Taxonomy and systematics Historically, cubozoans were classified as an order of Scyphozoa until 1973, when they were put in their own class due to their unique biological cycle (lack of strobilation) and morphology. At least 51 species of box jellyfish were known as of 2018. These are grouped into two orders and eight families. A few new species have since been described, and it is likely that additional undescribed species remain. Cubozoa represents the smallest cnidarian class with approximately 50 species. Class Cubzoa * Order Carybdeida ** Family Alatinidae ** Family Carukiidae ** Family Carybdeid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, although a few are anchored to the seabed by stalks rather than being motile. They are made of an umbrella-shaped main body made of mesoglea, known as the ''bell'', and a collection of trailing tentacles on the underside. Via pulsating contractions, the bell can provide propulsion for animal locomotion, locomotion through open water. The tentacles are armed with cnidocyte, stinging cells and may be used to capture prey or to defend against predators. Jellyfish have a complex biological life cycle, life cycle, and the medusa is normally the sexual phase, which produces planula larvae. These then disperse widely and enter a sedentary #Life cycle, polyp phase which may include asexual budding before reaching sexual maturity. Jellyfish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cnidocyte
A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ejects the toxin-containing cnidocyst which is responsible for the stings delivered by a cnidarian. The presence of this cell defines the phylum Cnidaria, which also includes the corals, sea anemones, hydrae, and jellyfish. Cnidocytes are single-use cells that need to be continuously replaced. Structure and function Each cnidocyte contains an organelle called a cnidocyst, which consists of a bulb-shaped capsule and a hollow, coiled tubule that is contained within. Immature cnidocytes are referred to as cnidoblasts or nematoblasts. The externally oriented side of the cell has a hair-like trigger called a cnidocil, a mechano-chemical receptor. When the trigger is activated, the tubule shaft of the cnidocyst is ejected and, in the case ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aragonite
Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation from marine and freshwater environments. The crystal lattice of aragonite differs from that of calcite, resulting in a different crystal shape, an orthorhombic crystal system with acicular crystal. Repeated twinning results in pseudo-hexagonal forms. Aragonite may be columnar or fibrous, occasionally in branching helictitic forms called ''flos-ferri'' ("flowers of iron") from their association with the ores at the Carinthian iron mines. Occurrence The type location for aragonite is Molina de Aragón in the Province of Guadalajara in Castilla-La Mancha, Spain, for which it was named in 1797. Aragonite is found in this locality as cyclic twins inside gypsum and marls of the Keuper facies of the Triassic. This type of aragoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colony (biology)
In biology, a colony is composed of two or more Biological specificity#Conspecific, conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey. Colonies can form in various shapes and ways depending on the organism involved. For instance, the bacterial colony is a cluster of identical cells (clones). These colonies often form and grow on the surface of (or within) a solid medium, usually derived from a single parent cell. Colonies, in the context of development, may be composed of two or more unitary (or solitary) organisms or be Modularity, modular organisms. Unitary organisms have determinate development (set life stages) from zygote to adult form and individuals or groups of individuals (colonies) are visually distinct. Modular organisms have indeterminate growth forms (life stages not set) through repeated iteration of genetically identi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
