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Peniagone Vitrea
''Peniagone vitrea'' is a species of deep-sea swimming sea cucumber in the family Elpidiidae. It is a detritivore and is found in the northern Pacific Ocean at abyssal depths. It was first described by the Swedish zoologist Hjalmar Théel in 1879, being one of the many deep sea animals discovered during the Challenger expedition of 1872–1876. Ecology ''Peniagone vitrea'' is one of a number of echinoderm species that show great variations in population density. Researchers in one study found that, over a sixteen-year period, two deep sea holothurians, ''Elpidia minutissima'' and ''Peniagone vitrea'', underwent a decline in density of the order of one to two magnitudes. It has been hypothesized that two factors that increase the likelihood of large swings in population are broadcast spawning and the possession of planktotrophic Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johan Hjalmar Théel
Johan Hjalmar Théel (14 June 1848 – 20 July 1937) was a Swedish zoologist and university professor. Early life Théel was born on 14 June 1848 in Säter, Sweden. He used to go on hunting trips along the coast of Norway in his youth and became fascinated by the plants and animals he encountered, especially the marine life. He met the zoologist Sven Ludvig Lovén who sparked his interest in sipunculid or peanut worms, especially the genus '' Phascolion''. He studied at Uppsala University and ''Phascolion'' was the subject for his thesis, written in 1875. He was also an artist and included his own illustrations in his published articles. In 1875, he accompanied the explorer Adolf Erik Nordenskiöld to the mouth of the Yenisei River in an attempt to find the Northeast Passage. He joined him on a similar voyage the following year and discovered a sea cucumber new to science, which he named ''Elpidia glacialis''. He was inducted into the Royal Swedish Academy of Sciences in 1884. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Cucumber
Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothurian () species worldwide is about 1,717, with the greatest number being in the Asia-Pacific region. Many of these are gathered for human consumption and some species are cultivated in aquaculture systems. The harvested product is variously referred to as '' trepang'', ''namako'', ''bêche-de-mer'', or ''balate''. Sea cucumbers serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detritus and other organic matter, after which bacteria can continue the decomposition process. Like all echinoderms, sea cucumbers have an endoskeleton just below the skin, calcified structures that are usually reduced to isolated microscopic ossicles (or sclerietes) joined by connective tissue. In some species these can sometim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elpidiidae
Elpidiidae is a family of deep-sea sea cucumbers. They have a translucent body with long and stout podia acting like legs. The mouth is surrounded by thick and short oral tentacles, and the dorsal part often shows pairs of elongated podia as well, pointing upwards. Some species can also show swimming appendages on top of the mouth. Sea pigs live in the darkest parts of the ocean. When introduced to warm waters, their bodies disintegrate, making them vulnerable to sudden heat changes. Genera The following genera are recognised in the family Elpidiidae: *'' Achlyonice'' Théel, 1879 *'' Amperima'' Pawson, 1965 *'' Ellipinion'' Hérouard, 1923 *'' Elpidia'' Théel, 1876 *'' Irpa'' Danielssen & Koren, 1878 *''Kolga'' Danielssen & Koren, 1879 *'' Peniagone'' Théel, 1882 *'' Penilpidia'' Gebruk, 1988 *'' Protelpidia'' Gebruk, 1983 *'' Psychrelpidia'' Hérouard, 1923 *'' Psychroplanes'' Gebruk, 1988 *'' Rhipidothuria'' Hérouard, 1901 *''Scotoplanes'' Théel, 1882 Image:Unidentifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detritivore
Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, vertebrates and plants that carry out coprophagy. By doing so, all these detritivores contribute to decomposition and the nutrient cycles. They should be distinguished from other decomposers, such as many species of bacteria, fungi and protists, which are unable to ingest discrete lumps of matter, but instead live by absorbing and metabolizing on a molecular scale (saprotrophic nutrition). The terms ''detritivore'' and ''decomposer'' are often used interchangeably, but they describe different organisms. Detritivores are usually arthropods and help in the process of remineralization. Detritivores perform the first stage of remineralization, by fragmenting the dead plant matter, allowing decomposers to perform the second stage of reminerali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east. At in area (as defined with a southern Antarctic border), this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about 32% of its total surface area, larger than Earth's entire land area combined .Pacific Ocean . '' Britannica Concise.'' 2008: Encyclopædia Britannica, Inc. The centers of both the |
Challenger Expedition
The ''Challenger'' expedition of 1872–1876 was a scientific program that made many discoveries to lay the foundation of oceanography. The expedition was named after the naval vessel that undertook the trip, . The expedition, initiated by William Benjamin Carpenter, was placed under the scientific supervision of Sir Charles Wyville Thomson—of the University of Edinburgh and Merchiston Castle School—assisted by five other scientists, including Sir John Murray, a secretary-artist and a photographer. The Royal Society of London obtained the use of ''Challenger'' from the Royal Navy and in 1872 modified the ship for scientific tasks, equipping it with separate laboratories for natural history and chemistry. The expedition, led by Captain George Nares, sailed from Portsmouth, England, on 21 December 1872. Other naval officers included Commander John Maclear. – pages 19 and 20 list the civilian staff and naval officers and crew, along with changes that took place during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian. The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elpidia Minutissima
''Elpidia minutissima'' is a species of deep-sea swimming sea cucumber in the family Elpidiidae. It is a detritivore and is found in the northern Pacific Ocean. Description Specimens collected from the Aleutian Trench averaged in length and had three pairs of dorsal podia whereas specimens collected from Station M in the northeastern Pacific Ocean at a depth of about had four pairs, two pairs on the dorsal surface and two pairs on the ventral surface, the hindermost of the ventral podia being shorter than the others. At times of low abundance, the average length of these sea cucumbers was similar to the specimens from the Aleutian Trench but at times of high abundance it increased to . It is possible that these two populations are not in fact the same species. Ecology ''Elpidia minutissima'' feeds on detritus on the seabed, the result of " marine snow" consisting of mucus, faeces and organic debris, that sink into the depths from surface waters. It plays an important part in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planktotrophic
Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals with a larva typically release many larvae into the water column, where the larvae develop before metamorphosing into adults. Marine larvae can disperse over long distances, although determining the actual distance is challenging, because of their size and the lack of a good tracking method. Knowing dispersal distances is important for managing fisheries, effectively designing marine reserves, and controlling invasive species. Theories on the evolution of a biphasic life history Larval dispersal is one of the most important topics in marine ecology, today. Many marine invertebrates and many fishes have a bi-phasic life cycle with a pelagic larva or pelagic eggs that can be transported over long distances, and a demersal or benthic adult. There are several theories behind why these organisms have evolved this biphasic life history: *La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive Feedback
Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the magnitude of the perturbation. That is, ''A produces more of B which in turn produces more of A''.Keesing, R.M. (1981). Cultural anthropology: A contemporary perspective (2nd ed.) p.149. Sydney: Holt, Rinehard & Winston, Inc. In contrast, a system in which the results of a change act to reduce or counteract it has negative feedback. Both concepts play an important role in science and engineering, including biology, chemistry, and cybernetics. Mathematically, positive feedback is defined as a positive loop gain around a closed loop of cause and effect. That is, positive feedback is Phase (waves), in phase with the input, in the sense that it adds to make the input larger. Positive feedback tends to cause Control theory#Stability, system i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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