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Terrestrial 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 '' Geosesa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gecarcinus Ruricola
''Gecarcinus ruricola'' is a species of land crab, terrestrial crab. It is the most terrestrial of the Caribbean Sea, 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 thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanhaipotamon
''Nanhaipotamon'' is a genus of freshwater crabs, in the subfamily Potamiscinae, found in southern China and Taiwan. As of 2018, 18 species have been described. The genus is named after the South China Sea (; literally: 'South Sea'), for it occurs mostly in coastal areas. The genus was first described by R. Bott in 1968 as ''Isolapotamon (Nanhaipotamon)'', i.e., a subgenus of ''Isolapotamon''. Description These crabs are relatively large, with a carapace breadth of up to . Depending on the species, the carapace may be vividly coloured, especially in males of ''Nanhaipotamon hongkongense, N. hongkongense'' (orange to red),'''' ''Nanhaipotamon aculatum, N. aculatum'' (dark blue) and ''Nanhaipotamon zhuhaiense, N. zhuhaiense'' (light blue). Chelipeds are usually unequal, more so in larger males, where one cheliped is relatively much larger than the other. This may be of use in territorial fights, as the crabs are very aggressive towards conspecifics.'''' Distribution and habitat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crabs
Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek), which typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. Their exoskeleton is often thickened and hard. They generally have five pairs of legs, and they have "pincers" or "claws" on the ends of the frontmost pair, scientifically termed the '' chelae''. They are present in all the world's oceans, in freshwater, and on land, often hiding themselves in small crevices or burrowing into sediment. Crabs are omnivores, feeding on a variety of food, including a significant proportion of algae, as well as detritus and other invertebrates. Crabs are widely consumed by humans as food, with over 1.5 million tonnes caught annually. True crabs first appeared in the fossil record during the Jurassic period, around 200 million years ago, achieving great diversity by the Cretaceous period; around 7,000 extant species in 96 families are known. A numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coconut Crab
The coconut crab (''Birgus latro'') is a terrestrial species of giant hermit crab, and is also known as the robber crab or palm thief. It is the largest terrestrial arthropod known, with a weight up to . The distance from the tip of one leg to the tip of another can be as wide as . It is found on islands across the Indian and Pacific Oceans, as far east as the Gambier Islands, Pitcairn Islands, and Caroline Island, and as far west as Zanzibar. While its range broadly shadows the distribution of the coconut palm, the coconut crab has been extirpated from most areas with a significant human population such as mainland Australia and Madagascar. 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 their ab ... [...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, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ... 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 * H ... [...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 family (biology), families. They show direct development and maternal care of a small number of offspring, in contrast to marine crabs, which release thousands of planktonic crustacean larvae, larvae. This limits the dispersal abilities of freshwater crabs, so they tend to be endemism, endemic to small areas. As a result, a large proportion are endangered species, threatened with extinction. Systematics More than 1,300 species description, 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 ... [...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 or bioproductivity at each trophic level in an ecosystem. A ''pyramid of energy'' shows how much energy is retained in the form of new biomass from 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 (pyramid of biomass for marine region) or take other shapes (spindle shaped pyramid). Ecological pyramids begin with 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Islands
An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been part of a continent. Oceanic islands can be formed from volcanic activity, grow into atolls from coral reefs, and form from sediment along shorelines, creating barrier islands. River islands can also form from sediment and debris in rivers. Artificial islands are those made by humans, including small rocky outcroppings built out of lagoons and large-scale land reclamation projects used for development. Islands are host to diverse plant and animal life. Oceanic islands have the sea as a natural barrier to the introduction of new species, causing the species that do reach the island to evolve in isolation. Continental islands share animal and plant life with the continent they split from. Depending on how long ago the continental island form ... [...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. The term excludes seawater and brackish water, but 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. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of vascular plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. Fresh water is the water resource that is of the most and immediate use to humans. Fresh water is not always pot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preadaptation
Exaptation or co-option is 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 be imperfectly developed ... [...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 salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mineral water, mineral-rich waters, such as chalybeate springs. Fresh water may encompass frozen water, frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ice pellets, 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, subterranea (geography), subterranean subterranean river, rivers and underground lake, lakes. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of vascular plants and most insects, amphibians, reptiles, mammals and birds need fresh water to sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physiological
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ systems, individual organ (biology), organs, cell (biology), cells, and biomolecules carry out chemistry, chemical and physics, physical functions in a living system. According to the classes of organisms, the field can be divided into clinical physiology, medical physiology, Zoology#Physiology, animal physiology, plant physiology, cell physiology, and comparative physiology. Central to physiological functioning are biophysics, biophysical and biochemical processes, homeostasis, homeostatic control mechanisms, and cell signaling, communication between cells. ''Physiological state'' is the condition of normal function. In contrast, ''pathology, pathological state'' refers to abnormality (behavior), abnormal conditions, including human diseases. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
