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Land Crabs
A number of lineages of crabs have evolved to live predominantly on land. Examples of terrestrial crabs are found in the families Gecarcinidae and Gecarcinucidae, as well as in selected genera from other families, such as '' Sesarma'', although the term "land crab" is often used to mean solely the family Gecarcinidae. Terrestriality and migration No clear distinction is made between "terrestrial", "semiterrestrial", and "aquatic" crabs. Rather, a continuum of terrestriality is displayed among the true crabs, although most land-adapted crabs must still return to water to release their eggs. Some species of terrestrial crabs can be found many kilometres from the sea, but have to complete annual migrations to the sea. For example, following the Indian Ocean monsoon, the Christmas Island red crab (''Gecarcoidea natalis'') migrates ', forming a "living carpet" of crabs. The crabs can travel up to in a day, and up to in total. Only a few land crabs, including certain ''Geoses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gecarcinus Ruricola
''Gecarcinus ruricola'' is a species of terrestrial crab. It is the most terrestrial of the Caribbean land crabs, and is found from western Cuba across the Antilles as far east as Barbados. Common names for ''G. ruricola'' include the purple land crab, black land crab, red land crab, and zombie crab. Description Four colour morphs exist within the species - black, red, yellow, and green. The carapace of ''G. ruricola'' grows in width at a rate of about per year, with the crabs reaching maturity after 5 years, and living for up to 10 years in total. ''G. ruricola'' crabs have a number of adaptations to terrestrial life, mostly regarding water conservation. They are nocturnal, to prevent the hot sun from drying them out. They also have a "nephritic pad", onto which urine is released, to be cleaned by microbes before the water is then reabsorbed. Distribution ''G. ruricola'' is found across much of the Caribbean, from Cuba and the Bahamas in the west through the Antilles to Barba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiwaripotamon
''Tiwaripotamon'' is a genus of freshwater crabs, recorded from China and Vietnam. Species * ''Tiwaripotamon annamense'' (Balss, 1914) * ''Tiwaripotamon araneum'' (Rathbun, 1904) * ''Tiwaripotamon austenianum'' (Wood-Mason, 1871) * ''Tiwaripotamon edostilus'' Ng & Yeo, 2001 * ''Tiwaripotamon pingguoense'' Dai & Naiyanetr, 1994 * ''Tiwaripotamon vietnamicum'' (Dang & Hô, 2002) * ''Tiwaripotamon vixuyenense'' Shih & Do, 2014 * ''Tiwaripotamon xiurenense'' Dai & Naiyanetr, 1994 References External links * * {{Taxonbar, from=Q18587498 Potamoidea Freshwater crustaceans of Asia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crabs
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fresh w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coconut Crab
The coconut crab (''Birgus latro'') is a species of terrestrial hermit crab, also known as the robber crab or palm thief. It is the largest terrestrial arthropod in the world, with a weight of up to . It can grow to up to in width from the tip of one leg to the tip of another. It is found on islands across the Indian Ocean, and parts of the Pacific Ocean as far east as the Gambier Islands, Pitcairn Islands and Caroline Island, similar to the distribution of the coconut palm; it has been extirpated from most areas with a significant human population, including mainland Australia and Madagascar. Coconut crabs also live off the coast of Africa near Zanzibar. The coconut crab is the only species of the genus ''Birgus'', and is related to the other terrestrial hermit crabs of the genus ''Coenobita''. It shows a number of adaptations to life on land. Juvenile coconut crabs use empty gastropod shells for protection like other hermit crabs, but the adults develop a tough exoskeleton on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coenobitidae
The Coenobitidae are the family of terrestrial hermit crabs, widely known for their land-living habits as adults. They are found in coastal tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ... regions around the world and require access to the ocean to breed. Although coenobitids are fully terrestrial as adults, they spend their marine life as planktonic larvae. Female coenobitids return to the sea to hatch their eggs and their larvae develop through planktonic zoeal stages to a megalopa, in a similar way as the marine hermit crabs. Just like these species, after settlement, terrestrial hermit crabs megalopae recognize and co-opt gastropods shells, before migrating into the land and molting to the first crab stage. The 17 species are placed in two genera: References * Ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater Crab
Around 1,300 species of freshwater crabs are distributed throughout the tropics and subtropics, divided among eight families. They show direct development and maternal care of a small number of offspring, in contrast to marine crabs, which release thousands of planktonic larvae. This limits the dispersal abilities of freshwater crabs, so they tend to be endemic to small areas. As a result, a large proportion are threatened with extinction. Systematics More than 1,300 described species of freshwater crabs are known, out of a total of 6,700 species of crabs across all environments. The total number of species of freshwater crabs, including undescribed species, is thought to be up to 65% higher, potentially up to 2,155 species, although most of the additional species are currently unknown to science. They belong to eight families, each with a limited distribution, although various crabs from other families are also able to tolerate freshwater conditions ( euryhaline) or are secon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Pyramid
An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the Biomass (ecology), biomass or Primary production, bioproductivity at each trophic level in a given ecosystem. A ''pyramid of energy'' shows how much energy is retained in the form of new biomass at each trophic level, while a ''pyramid of biomass'' shows how much biomass (the amount of living or organic matter present in an organism) is present in the organisms. There is also a ''pyramid of numbers'' representing the number of individual organisms at each trophic level. Pyramids of energy are normally upright, but other pyramids can be inverted or take other shapes. Ecological pyramids begin with autotroph, producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Island
An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. Sedimentary islands in the Ganges delta are called chars. A grouping of geographically or geologically related islands, such as the Philippines, is referred to as an archipelago. There are two main types of islands in the sea: continental and oceanic. There are also artificial islands, which are man-made. Etymology The word ''island'' derives from Middle English ''iland'', from Old English ''igland'' (from ''ig'' or ''ieg'', similarly meaning 'island' when used independently, and -land carrying its contemporary meaning; cf. Dutch ''eiland'' ("island"), German ''Eiland'' ("small island")). However, the spelling of the word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Document Format
Portable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems.Adobe Systems IncorporatedPDF Reference, Sixth edition, version 1.23 (53 MB) Nov 2006, p. 33. Archiv/ref> Based on the PostScript language, each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, vector graphics, raster images and other information needed to display it. PDF has its roots in "The Camelot Project" initiated by Adobe co-founder John Warnock in 1991. PDF was standardized as ISO 32000 in 2008. The last edition as ISO 32000-2:2020 was published in December 2020. PDF files may contain a variety of content besides flat text and graphics including logical structuring elements, interactive elements such as annotations and form-fields, layers, rich media (including video con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater Forum
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non- salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of higher plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. Fresh water is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preadaptation
Exaptation and the related term co-option describe a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour. Bird feathers are a classic example. Initially they may have evolved for temperature regulation, but later were adapted for flight. When feathers were first used to aid in flight, that was an exaptive use. They have since then been shaped by natural selection to improve flight, so in their current state they are best regarded as adaptations for flight. So it is with many structures that initially took on a function as an exaptation: once molded for a new function, they become further adapted for that function. Interest in exaptation relates to both the process and products of evolution: the process that creates complex traits and the products (functions, anatomical structures, biochemicals, etc.) that may b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fresh Water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non- salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of higher plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. Fresh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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