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Sex Change In Animals
Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, a sequential hermaphrodite produces eggs (female gametes) and sperm (male gametes) at different stages in life. Species that can undergo these changes from one sex to another do so as a normal event within their reproductive cycle that is usually cued by either social structure or the achievement of a certain age or size. In animals, the different types of change are male to female (protandry or protandrous hermaphroditism), female to male (protogyny or protogynous hermaphroditism), bidirectional (serial or bidirectional hermaphroditism). Both protogynous and protandrous hermaphroditism allow the organism to switch between functional male and functional female. Bidirectional hermaphrodites have the capacity for sex change in either directi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botany
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek word (''botanē'') meaning " pasture", " herbs" "grass", or " fodder"; is in turn derived from (), "to feed" or "to graze". Traditionally, botany has also included the study of fungi and algae by mycologists and phycologists respectively, with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress. Nowadays, botanists (in the strict sense) study approximately 410,000 species of land plants of which some 391,000 species are vascular plants (including approximately 369,000 species of flowering plants), and approximately 20,000 are bryophytes. Botany originated in prehistory as herbalism with the efforts of early humans to identify – and later cultivate – ed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clupeiformes
Clupeiformes is the order of Actinopterygii, ray-finned fish that includes the herring family, Clupeidae, and the anchovy family, Engraulidae. The group includes many of the most important Forage fish, forage and food fish. Clupeiformes are physostomes, which means that their gas bladder has a pneumatic duct connecting it to the Gut (zoology), gut. They typically lack a lateral line, but still have the eyes, Fish fin, fins and Fish scale, scales that are common to most fish, though not all fish have these attributes. They are generally silvery fish with streamlined, spindle-shaped, bodies, and they often Shoaling and schooling, school. Most species eat plankton which they filter from the water with their gill rakers. The former order of Isospondyli was subsumed mostly by Clupeiformes, but some isospondylous fishes (isospondyls) were assigned to Osteoglossiformes, Salmoniformes, Cetomimiformes, etc. Families The order includes about 405 species in seven families: * Order Clup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fecundity
Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to produce offspring, measured by the number of gametes (eggs), seed set, or asexual propagules. Superfecundity refers to an organism's ability to store another organism's sperm (after copulation) and fertilize its own eggs from that store after a period of time, essentially making it appear as though fertilization occurred without sperm (i.e. parthenogenesis). Human demography Human demography considers only human fecundity, at its culturally differing rates, while population biology studies all organisms. The term ''fecundity'' in population biology is often used to describe the rate of offspring production after one time step (often annual). In this sense, fecundity may include both birth rates and survival of young to that time step. Whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalassoma Lunare 1
''Thalassoma'' is a genus of wrasses native to the Atlantic, Indian and Pacific Oceans. Many species occasionally make their way into the aquarium trade. Species The currently recognized species in this genus are: * '' Thalassoma amblycephalum'' (Bleeker, 1856) (blunt-headed wrasse) * '' Thalassoma ascensionis'' ( Quoy & Gaimard, 1834) (Ascension wrasse) * '' Thalassoma ballieui'' ( Vaillant & Sauvage, 1875) (blacktail wrasse) * ''Thalassoma bifasciatum'' (Bloch, 1791) (bluehead wrasse) * '' Thalassoma cupido'' (Temminck & Schlegel, 1845) (Cupid wrasse) * '' Thalassoma duperrey'' (Quoy & Gaimard, 1824) (saddle wrasse) * '' Thalassoma genivittatum'' (Valenciennes, 1839) (red-cheek wrasse) * '' Thalassoma grammaticum'' C. H. Gilbert, 1890 (sunset wrasse) * ''Thalassoma hardwicke'' ( J. W. Bennett, 1830) (sixbar wrasse) * '' Thalassoma hebraicum'' ( Lacépède, 1801) (goldbar wrasse) * '' Thalassoma heiseri'' J. E. Randall & A. J. Edwards, 1984 (Pitcairn rainbow wrasse) * '' Tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysmata Debelius
''Lysmata debelius'' is a species of cleaner shrimp indigenous to the Indo-Pacific. It is popular in the aquarium trade, where it is known as the fire shrimp, blood shrimp or scarlet cleaner shrimp. Taxonomy ''Lysmata debelius'' was first described by A. J. Bruce in 1983, based on type material from Polillo Island in the Philippines. The specific epithet commemorates Helmut Debelius, who had collected the specimens and sent them to a zoologist for identification. A divergent population from Ari Atoll in the Maldives was later described as a separate species, '' L. splendida'', by Rudolf Burukovsky. Description ''Lysmata debelius'' grows up to long, with males and functional hermaphrodites appearing similar. It has a red body, with conspicuous white antennae and white tips to the third to fifth pereiopods. There are white dots on the cephalothorax and legs; white dots on the abdomen distinguish ''L. splendida'' from ''L. debelius''. Ecology ''Lysmata debelius'' is one of a gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysmata
''Lysmata'' is a genus of shrimp in the infraorder Caridea, the caridean shrimp. The genus belongs to the family Lysmatidae. ''Lysmata'' are popular ornamental shrimp in the marine aquarium trade for their bright color patterns, interesting behaviors, and ability to control certain aquarium pests such as sea anemones of the genus ''Aiptasia''. They are known to command high prices on the pet market. The genus is informally divided into two main categories. Some species are cleaner shrimp which "clean" parasites and other material from fish, live in pairs, and are brightly colored, often in contrasting reds and yellows with white antennae. Other species are the "peppermint shrimp", which have semi-translucent, red-banded bodies, and live in large groups. Some peppermint shrimp perform cleaning behaviors, but less actively than do the cleaner shrimp. The genus has been studied with interest due to its unusual sexual system, protandric simultaneous hermaphroditism. While some oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speyeria Mormonia
''Speyeria mormonia,'' commonly known as the Mormon fritillary, is a North American butterfly belonging to the family Nymphalidae. It is highly diverse, having differentiated into several subspecies which occupy a wide geographic range. ''S. mormonia'' exhibits extreme protandry, which is the emergence of male adults before female adults. This has several consequences on male and female behavior. Habitat specificity is still being investigated, as there are few known environmental predictors, and ''S. mormonia'' appears to be associated with a wide range of habitats. This species is not under threat, and conservation efforts are generally not necessary. Geographic range ''S. mormonia'' is found throughout western North America, with significant populations in both the United States and Canada.Boggs, Carol L., and Charles L. Ross. "The effect of adult food limitation on life history traits in Speyeria mormonia (Lepidoptera: Nymphalidae)." ''Ecology'' 74.2 (1993): 433-441.Marks, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copulation (zoology)
In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. This is an aspect of mating. Many animals that live in water use external fertilization, whereas internal fertilization may have developed from a need to maintain gametes in a liquid medium in the Late Ordovician epoch. Internal fertilization with many vertebrates (such as all reptiles, some fish, and most bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...s) occurs via cloacal copulation, known as cloacal kiss (see also hemipenis), while mammals copulate vaginally, and many primitive (biology), basal vertebrates reproduce sexually with external fertilization. In spiders and insects Spiders are often confused with insects, b ... [...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 flagellum, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laevapex Fuscus
''Laevapex fuscus'', the dusky ancylid, is a species of small, freshwater, air-breathing limpet, an aquatic pulmonate gastropod mollusc or micromollusc in the family Planorbidae, the ram's horn snails and their allies. Geographic distribution ''L. fuscus'' is found throughout North America east of the Great Plains, except for mountainous areas. It has been recorded in Canada, the United States, Jamaica and Puerto Rico. Description ''L. fuscus'' was originally described as ''Ancylus fuscus'' in 1841 by Charles Baker Adams: :"''Shell'' thin, transparent without the epidermis, not much elevated, elliptical, moderately curved at the sides; ''epidermis'' brown, visible through the shell, giving it the appearance of having the same color, thick, rough, slightly extending beyond the margin of the shell; ''apex'' obtuse, moderately prominent, scarcely behind the middle, inclining to the right, so as to have only two fifths of the width on that side. :Length, , width, ; height, . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenophora
Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are the largest animals to swim with the help of cilia. Depending on the species, adult ctenophores range from a few millimeters to in size. Only 100 to 150 species have been validated, and possibly another 25 have not been fully described and named. The textbook examples are cydippids with egg-shaped bodies and a pair of retractable tentacles fringed with tentilla ("little tentacles") that are covered with colloblasts, sticky cells that capture prey. Their bodies consist of a mass of jelly, with a layer two cells thick on the outside, and another lining the internal cavity. The phylum has a wide range of body forms, including the egg-shaped cydippids with retractable tentacles that capture prey, the flat generally combless plat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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