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Chaenocephalus Aceratus
The blackfin icefish (''Chaenocephalus aceratus''), also known as the Scotia Sea icefish, is a species of Channichthyidae, crocodile icefish belonging to the family Channichthyidae. The blackfin icefish belongs to Notothenioidei, a suborder of fishes that accounts for 90% of the fish fauna on the Antarctic continental shelf. Icefishes, also called white-blooded fishes, are a unique family in that they are the only known vertebrates to lack Hemoglobin, haemoglobin, making their blood oxygen carrying capacity just 10% that of other Teleost, teleosts. Icefishes have translucent blood and creamy white gills. Taxonomy The blackfin icefish was first formally Species description, described as ''Chaenichthys aceratus'' in 1906 by the Swedish zoologist Einar Lönnberg with the type locality given as South Georgia Island. In 1913 the English people, English ichthyologist Charles Tate Regan described a new subgenus of ''Channichthys'', ''Chaenocephalus'' with the blackfin icefish as its only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Tate Regan
Charles Tate Regan FRS (1 February 1878 – 12 January 1943) was a British ichthyologist, working mainly around the beginning of the 20th century. He did extensive work on fish classification schemes. Born in Sherborne, Dorset, he was educated at Derby School and Queens' College, Cambridge and in 1901 joined the staff of the Natural History Museum, where he became Keeper of Zoology, and later director of the entire museum, in which role he served from 1927 to 1938. Regan was elected Fellow of the Royal Society in 1917. Regan mentored a number of scientists, among them Ethelwynn Trewavas, who continued his work at the British Natural History Museum. Species Among the species he described is the Siamese fighting fish (''Betta splendens''). In turn, a number of fish species have been named ''regani'' in his honour: *A Thorny Catfish '' Anadoras regani'' (Steindachner, 1908) *The Dwarf Cichlid '' Apistogramma regani'' *'' Apogon regani'' *A Catfish '' Astroblepus regani'' * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypy
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. In contrast, an oligotypic taxon contains more than one but only a very few subordinate taxa. Examples Just as the term ''monotypic'' is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within a family. Some examples of monotypic groups are: Plants * In the order Amborellales, there is only one family, Amborellaceae and there is only one genus, '' Amborella'', and in this genus there is only one species, namely ''Amborella trichopoda.' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where vegetation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian oceans but larger than the Arctic Ocean. Over the past 30 years, the Southern Ocean has been subject to rapid climate change, which has led to changes in the marine ecosystem. By way of his voyages in the 1770s, James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Ocean's northern boundary or even existence, considering the waters as various parts of the Pacific, Atlantic, and Indian oceans, instead. However, according to Commodore John Leech of the International Hydrographic Organization (IHO), recent oceanographic research has discovered the importance of Southern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spawn (biology)
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and marine reptile, reptiles, reproduce through the process of spawning. Spawn consists of the reproductive cells (gametes) of many aquatic animals, some of which will become fertilized and produce offspring. The process of spawning typically involves females releasing Ovum, ova (unfertilized eggs) into the water, often in large quantities, while males simultaneously or sequentially release spermatozoa (milt) to fertilize the eggs. Most fish reproduce by spawning, as do most other aquatic animals, including crustaceans such as crabs and shrimps, molluscs such as oysters and squid, echinoderms such as sea urchins and sea cucumbers, amphibians such as frogs and newts, aquatic insects such as mayflies and mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal Fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans adapted to their marine environments, including most numerously fish, but also mammals such as cetaceans (whales, dolphins, and porpoises), and even extinct ancient marine reptiles such as various known species of ichthyosaurs. Most species have only one dorsal fin, but some have two or three. Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large cetaceans to identify individuals in the field. The bony or cartilaginous bones that support the base of the dorsal fin in fish are called ''pterygiophores''. Functions The main purpose of the dorsal fin is to stabilize the animal against rollin ... [...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] |
Buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can occur only in a no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swim Bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth without having to expend energy in swimming. Also, the Dorsum (biology), dorsal position of the swim bladder means the center of mass is below the centroid, center of volume, allowing it to act as a stabilizing agent. Additionally, the swim bladder functions as a resonator, resonating chamber, to produce or receive sound. The swim bladder is evolutionarily Homology (biology), homologous to the lungs. Charles Darwin remarked upon this in ''On the Origin of Species''.Darwin, Charles (1859''Origin of Species''Page 190, reprinted 1872 by D. Appleton. Darwin reasoned that the lung in air-breathing vertebrates had derived from a more primitive swim bladder. In the embryonic stages, some species, such as Ophioblennius atlanticus, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelvic Fin
Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two endochondrally-derived bony girdles attached to bony radials. Dermal fin rays (lepidotrichia) are positioned distally from the radials. There are three pairs of muscles each on the dorsal and ventral side of the pelvic fin girdle that abduct and adduct the fin from the body. Pelvic fin structures can be extremely specialized in actinopterygians. Gobiids and lumpsuckers modify their pelvic fins into a sucker disk that allow them to adhere to the substrate or climb structures, such as waterfalls. In priapiumfish, males have modified their pelvic structures into a spiny copulatory device that grasps the female during mating. File:Pelvic fin skeleton.png, Pelvic fin skeleton for ''Danio rerio'', zebrafish. File:Zuignap waarmee de zwartbekgrond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angiogenesis
Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting. Vasculogenesis is the embryonic formation of endothelial cells from mesoderm cell precursors, and from neovascularization, although discussions are not always precise (especially in older texts). The first vessels in the developing embryo form through vasculogenesis, after which angiogenesis is responsible for most, if not all, blood vessel growth during development and in disease. Angiogenesis is a normal and vital process in growth and development, as well as in wound healing and in the formation of granulation tissue. However, it is also a fundamental step in the transition of tumors from a benign state to a malignant one, leading to the use of angiogenesis inhibitors in the treatment of cancer. The essential role of angiogenesis in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ossification
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue: Intramembranous ossification is the direct laying down of bone into the primitive connective tissue ( mesenchyme), while endochondral ossification involves cartilage as a precursor. In fracture healing, endochondral osteogenesis is the most commonly occurring process, for example in fractures of long bones treated by plaster of Paris, whereas fractures treated by open reduction and internal fixation with metal plates, screws, pins, rods and nails may heal by intramembranous osteogenesis. Heterotopic ossification is a process resulting in the formation of bone tissue that is often atypical, at an extraskeletal location. Calcification is often confused with ossification. Calcification is sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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