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Polyzoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869living species are known. At least two genera are solitary (''Aethozooides'' and ''Monobryozoon''); the rest are colonial. The terms Polyzoa and Bryozoa were introduced in 1830 and 1831, respectively. Soon after it was named, another group of animals was discovered whose filtering mechanism looked similar, so it was included in Bryozoa until 1869, when the two groups were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lophophore
The lophophore () is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata.Introduction to the Lophotrochozoa – Retrieved 3 May 2010 All lophophores are found in aquatic organisms. Etymology ''Lophophore'' is derived from the Greek ''lophos'' (crest, tuft) and ''-phore'', ''-phoros'' (φορος) (bearing), a derivative of ''phérein'' (φέρειν) (to bear); thus crest-bearing.Characteristics The lophophore can most easily be described as a ring of ciliated tentacles surrounding the mouth, but it is often horseshoe-shaped or coiled. Phoronids have thei ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pywackia
''Pywackia'' is a contentious Cambrian fossil that has been interpreted as the earliest (total group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...) Bryozoan, and the only representative of that phylum in the Cambrian period. Its Bryozoan credentials have been called into question, but the octocoral alternative is equally unconvincing, and there are reasons to suggest a position in the Stenolaemata stem lineage. References {{Taxonbar, from=Q20817953 Fossils of Mexico Enigmatic prehistoric animal genera Cambrian invertebrates Cambrian fossil record Fossil taxa described in 2010 Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovum
The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non- motile). If the male gamete ( sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous. A nonmotile female gamete formed in the oogonium of some algae, fungi, oomycetes, or bryophytes is an oosphere. When fertilized the oosphere becomes the oospore. When egg and sperm fuse during fertilisation, a diploid cell (the zygote) is formed, which rapidly grows into a new organism. History While the non-mammalian animal egg was obvious, the doctrine ''ex ovo omne vivum'' ("every living nimal comes froman egg"), associated with William Harvey (1578–1657), was a rejection of spontaneous generation and preformationism as well as a bold assumption that mammals also reprodu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm. Sperm cells form during the process known as spermatogenesis, which in amniotes (reptiles and mammals) takes place in the seminiferous tubules of the testes. This process involves the production of several successive sperm cell precursors, starting with spermatogonia, which differentiate into spermatocytes. The spermatocytes then undergo meiosis, reducing their chromosome number by half, which produces spermatids. The spermatids then mature and, in animals, construct a tail, or fla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. For example, the great majority of tunicates, pulmonate molluscs, opisthobranch, earthworms, and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites. Animal species having different sexes, male and female, are called gonochoric, which is the opposite of hermaphrodite. There are also species where hermaphrodites exist alongside males (called androdioecy) or alongside females (called gynodioecy), or all three exist in the same species (called trioecy); these three syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypide
The polypide in bryozoans encompasses most of the organs and tissues of each individual zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zoo .... This includes the tentacles, tentacle sheath, U-shaped digestive tract, musculature and nerve cells. It is housed in the zooidal exoskeleton, which in cyclostomes is tubular and in cheilostomes is box-shaped. See also Bryozoan Anatomy References Bryozoology Protostome anatomy {{bryozoan-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoskeleton
An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the larger kinds of exoskeletons are known as " shells". Examples of exoskeletons within animals include the arthropod exoskeleton shared by chelicerates, myriapods, crustaceans, and insects, as well as the shell of certain sponges and the mollusc shell shared by snails, clams, tusk shells, chitons and nautilus. Some animals, such as the turtle, have both an endoskeleton and an exoskeleton. Role Exoskeletons contain rigid and resistant components that fulfill a set of functional roles in many animals including protection, excretion, sensing, support, feeding and acting as a barrier against desiccation in terrestrial organisms. Exoskeletons have a role in defense from pests and predators, support and in providing an attachment framewo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomineralization
Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; all six taxonomic kingdoms contain members that are able to form minerals, and over 60 different minerals have been identified in organisms. Examples include silicates in algae and diatoms, carbonates in invertebrates, and calcium phosphates and carbonates in vertebrates. These minerals often form structural features such as sea shells and the bone in mammals and birds. Organisms have been producing mineralized skeletons for the past 550 million years. Calcium carbonates and calcium phosphates are usually crystalline, but silica organisms (sponges, diatoms...) are always non crystalline minerals. Other examples include copper, iron and gold deposits involving bacteria. Biologically formed minerals often have special uses such as ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order (biology)
Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. For some groups of organisms, their orders may fol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species Diversity
Species diversity is the number of different species that are represented in a given community (a dataset). The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest (where all species may not be equally abundant). Meanings of species diversity may include species richness, taxonomic or phylogenetic diversity, and/or species evenness. Species richness is a simple count of species. Taxonomic or phylogenetic diversity is the genetic relationship between different groups of species. Species evenness quantifies how equal the abundances of the species are.Hill, M. O. (1973) Diversity and evenness: a unifying notation and its consequences. Ecology, 54, 427–432Tuomisto, H. (2010) A diversity of beta diversities: straightening up a concept gone awry. Part 1. Defining beta diversity as a function of alpha and gamma diversity. Ecography, 33, 2-22. Tuomisto, H. 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheilostomata
Cheilostomatida, also called Cheilostomata, is an order of Bryozoa in the class Gymnolaemata. They are exclusively marine, colonial invertebrate animals. Cheilostome colonies are composed of calcium carbonate and grow on a variety of surfaces, including rocks, shells, seagrass and kelps. The colony shapes range from simple encrusting sheets to erect branching and even unattached forms. As in other bryozoan groups, each colony is composed of a few to thousands of individual polypides. Each individual has a U-shaped gut, and no respiratory, circulatory, or nerve system. Unique among bryozoans, cheilostome polypides are housed in a box-shaped zooids, which do not grow larger once the zooid is mature. The opening through which the polypide protrudes is protected by a calcareous or chitinous lidlike structure, an operculum. Cheilostomes possess avicularia, which have modified the operculum into a range of mandibles (possibly for defense) or hair-like setae (possibly for cleanin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
