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Astrobrachion Adhaerens
''Astrobrachion adhaerens'' is a basket star in the Euryalidae family. Along with '' A. constrictum'', it is one of only two species in the genus '' Astrobrachion''. Both species live in association with soft corals in moderately deep water. It is endemic to the west, north and east coasts of Australia, the Kermadec Islands and Lord Howe Island. Euryalids are the least well known ophiuroids. There is even lesser knowledge about ''A. adhaerens'' available. However it is closely related to its only sister species, ''A. constrictum,'' and information about this species and the family as a whole can provide insight into the anatomy, morphology, reproduction, and suspension feeding habits of ''A. adhaerens''. Taxonomy The taxonomy and phylogeny of species in the order Euryalida and class Ophiuroidea has been ambiguous and continues to be investigated. Euryalid fossils date back to strata as young as Cretaceous and Neogene. In the past, the ophiuroids were classified as eith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basket Star
The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristic repeatedly branched arms (a shape known as "basket stars", which includes most Gorgonocephalidae and two species in the family Euryalidae), while the other species have very long and curling arms, and go rather by the name of "snake stars" (mostly abyssal species). Many of them live in deep sea habitats or cold waters, though some basket stars can be seen at night in shallow tropical reefs. Most young basket stars live on specific type of coral. In the wild they may live up to 35 years. They weigh up to Like other echinoderms, basket stars lack blood and achieve gas exchange via their water vascular system. The basket stars are the largest ophiuroids with '' Gorgonocephalus stimpsoni'' measuring up to 70 cm in arm length with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republika sang Filipinas * ibg, Republika nat Filipinas * ilo, Republika ti Filipinas * ivv, Republika nu Filipinas * pam, Republika ning Filipinas * krj, Republika kang Pilipinas * mdh, Republika nu Pilipinas * mrw, Republika a Pilipinas * pag, Republika na Filipinas * xsb, Republika nin Pilipinas * sgd, Republika nan Pilipinas * tgl, Republika ng Pilipinas * tsg, Republika sin Pilipinas * war, Republika han Pilipinas * yka, Republika si Pilipinas In the recognized optional languages of the Philippines: * es, República de las Filipinas * ar, جمهورية الفلبين, Jumhūriyyat al-Filibbīn is an archipelagic country in Southeast Asia. It is situated in the western Pacific Ocean and consists of around 7,641 islands t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germinal Epithelium (female)
The ovarian surface epithelium, also called the germinal epithelium of Waldeyer, or coelomic epithelium is a layer of simple squamous-to-cuboidal epithelial cells covering the ovary. The term ''germinal epithelium'' is a misnomer as it does not give rise to primary follicles. Composition These cells are derived from the mesoderm during embryonic development and are closely related to the mesothelium of the peritoneum. The germinal epithelium gives the ovary a dull gray color as compared with the shining smoothness of the peritoneum; and the transition between the mesothelium The mesothelium is a membrane composed of simple squamous epithelial cells of mesodermal origin, which forms the lining of several body cavities: the pleura (pleural cavity around the lungs), peritoneum (abdominopelvic cavity including the mesente ... of the peritoneum and the cuboidal cells which cover the ovary is usually marked by a line around the anterior border of the ovary. Diseases Ovarian surface e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germinal Epithelium (male)
The germinal epithelium is the epithelial layer of the seminiferous tubules of the testicles. It is also known as the wall of the seminiferous tubules. The cells in the epithelium are connected via tight junctions. There are two types of cells in the germinal epithelium. The large Sertoli cells (which are not dividing) function as supportive cells to the developing sperm. The second cell type are the cells belonging to the spermatogenic cell lineage. These develop to eventually become sperm cells (spermatozoon A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, t ...). Typically, the spermatogenic cells will make four to eight layers in the germinal epithelium.Junqueira's Basic Histology: Text and Atlas, Thirteenth Edition References External links * - "Male Reproductive System: test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes are haploid cells. Some hermaphroditic animals have a type of gonad called an ovotestis. Evolution It is hard to find a common origin for gonads, but gonads most likely evolved independently several times. Regulation The gonads are controlled by luteinizing hormone and follicle-stimulating hormone, produced and secreted by gonadotropes or gonadotrophins in the anterior pituitary gland. This secretion is regulated by gonadotropin-releasing hormone produced in the hypothalamus. Development Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of genital ridges, which are only l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerated dim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecy
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only about half the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. Dioecy is a dimorphic sexual system, alongside gynodioecy and androdioecy. In zoology In zoology, dioecious species may be opposed to hermaphroditic species, meaning that an individual is either male or female, in which case the synonym gonochory is more often used. Most animal species are dioecious (gon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermal Tissue
The epidermis (from the Greek ''ἐπιδερμίς'', meaning "over-skin") is a single layer of cells that covers the leaves, flowers, roots and stems of plants. It forms a boundary between the plant and the external environment. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients. The epidermis of most leaves shows dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. Woody stems and some other stem structures such as potato tubers produce a secondary covering called the periderm that replaces the epidermis as the protective covering. Description The epidermis is the outermost cell layer of the primary plant body. In some older works the cells of the leaf epidermis have been regarded as specialized parenchyma cells,Hill, J. Ben; Overholts, Lee O; Popp, He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral (anatomy)
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabularies for subdisciplines of anatom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Co-occurrence
In linguistics, co-occurrence or cooccurrence is an above-chance frequency of occurrence of two terms (also known as coincidence or concurrence) from a text corpus alongside each other in a certain order. Co-occurrence in this linguistic sense can be interpreted as an indicator of semantic proximity or an idiomatic expression. Corpus linguistics and its statistic analyses reveal patterns of co-occurrences within a language and enable to work out typical collocations for its lexical items. A ''co-occurrence restriction'' is identified when linguistic elements never occur together. Analysis of these restrictions can lead to discoveries about the structure and development of a language. Co-occurrence can be seen an extension of word counting in higher dimensions. Co-occurrence can be quantitatively described using measures like correlation or mutual information. See also * Distributional hypothesis * Statistical semantics * Co-occurrence matrix * Co-occurrence networks * Similarity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nephtheidae
Nephtheidae is a family of soft corals in the phylum Cnidaria. Members of this family are known as carnation corals, tree corals or colt soft corals. They are very attractive and show a wide range of rich and pastel colours including reds, pinks, yellows and purples. They are popular with reef aquarium hobbyists. Most of these corals are arborescent and have little knobs on the end of their rubbery branches. The coral polyps tend to retract in the daytime which gives these corals their alternative name of broccoli corals because of their resemblance to the vegetable. At night the polyps emerge and extend their tentacles to feed, looking like little bunches of flowers on the ends of the branches. Genera The World Register of Marine Species includes the following genera in this family: *'' Capnella'' Gray, 1869 *'' Chondronephthya'' Utinomi, 1960 *'' Chromonephthea'' van Ofwegen, 2005 *'' Coronephthya'' Utinomi, 1966 *''Dendronephthya'' Kuekenthal, 1905 *'' Drifa'' Danielssen, 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
