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Orchitophrya Stellarum
''Orchitophrya stellarum'' is a species of single-celled marine ciliates, a member of the class Oligohymenophorea. It is found living freely in the north Atlantic and Pacific Oceans but is also parasitic, being found inside the gonads of starfish. Biology ''Orchitophrya stellarum'' tolerates a sea temperature range of between and and a salinity range of between 2 and at least 30 parts per thousand of salt equivalent. The lower the temperature, the lower the acceptable level of salinity. Growth is most rapid at 24 °C. It is a facultative parasite of sea stars in the Asteriidae family. It seems to be able to survive in the open sea indefinitely as long as there is a supply of bacteria and tissue detritus on which it can feed. Parasitism ''Orchitophrya stellarum'' is often associated with sea stars and other invertebrates, living on their outer surface and feeding on sloughed-off epidermal tissue. It only appears to become parasitic when the male host starfish has ripe gona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterias Rubens
The common starfish, common sea star or sugar starfish (''Asterias rubens'') is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae, it has five arms and usually grows to between 10–30 cm across, although larger specimens (up to 52 cm across) are known. The common starfish is usually orange or brownish in color, and sometimes violet; specimens found in deeper waters are pale. The common starfish is found on rocky and gravelly substrates where it feeds on mollusks and other benthic invertebrates. Description The common starfish normally has five arms, broad at their base and gradually tapering to a point at their tips, which are often turned up slightly. There is a line of short white spines running along the centre of the aboral (upper) surface of the arms with low, soft mounds called papulae on either side. The oral (lower) surfaces of the arms have rows of small tube feet, used in locomotion and feeding. The starf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterias Forbesi
''Asterias forbesi'', commonly known as Forbes sea star, is a species of starfish in the family Asteriidae. It is found in shallow waters in the northwest Atlantic Ocean and the Caribbean Sea. Description left, Underside of ''Asterias forbesi'' ''Asterias forbesi'' usually has 5 arms but occasionally has 4 or 6. Like many starfish species, the upper surface is covered in blunt conical projections giving it a rough feel. Some of these are pedicellariae, minute pincers that can grip objects. The arms are plump, broad at the base and tapering to a blunt tip. This starfish grows to about in diameter with an arm length of about . The madreporite is usually pink and is visible near the edge of the disc. There are several rows of tube feet on the underside on either side of the ambulacral groove that run down the centre of each arm. The colour of the upper side is variable, ranging from brown or tan to reddish-purple and the underside is usually pale brown. Near the tip on the unders ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evasterias Troschelii
''Evasterias troschelii'' is a species of starfish in the family Asteriidae. Its common names include the mottled star, false ochre sea star and Troschel's true star. It is found in Kamchatka and the north western coast of North America. Taxonomy The description of this species was first formally published in 1862 by William Stimpson under the name ''Asterias troschelii'' (Stimpson first presented the new species in a lecture at the Boston Society of Natural History in 1861). The holotype was collected in Puget Sound, Washington. Only part of one arm still remains of this smallish specimen at the United States National Museum. It was moved to the new genus '' Evasterias'' by Addison Emery Verrill in 1914, with as the type species. Verrill published five new varieties (''alveolata'', ''densa'', ''parvispina'', ''rudis'' and ''subnodosa'') besides the nominate variety, and also published ''E. acanthostoma'' in 1914. Alexander Michailovitsch Djakonov synonymised all of Verrill's va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of Outline of life forms, life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes. The eukaryotes emerged within the archaeal Kingdom (biology), kingdom Asgard (Archaea), Promethearchaeati and its sole phylum Promethearchaeota. This implies that there are only Two-domain system, two domains of life, Bacteria and Archaea, with eukaryotes incorporated among the Archaea. Eukaryotes first emerged during the Paleoproterozoic, likely as Flagellated cell, flagellated cells. The leading evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonopore
A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects, have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female, it is the opening of the common oviduct, and in the male, it is the opening of the ejaculatory duct. The position of the gonopore varies considerably between groups, but is generally constant within groups, allowing its position to be used as a "segmental marker". In Malacostraca, it is on the sixth thoracic segment; in Symphyla, it is on the fourth trunk segment; in arachnids, it is on the second segment of the opisthosoma. In insects and centipedes, the gonopores are close to the animal's tail, while in millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Dipl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciliate Species
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group (although the peculiar Suctoria only have them for part of their life cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation. Ciliates are an important group of protists, common almost anywhere there is water—in lakes, ponds, oceans, rivers, and soils, including anoxic and oxygen-depleted habitats. About 4,500 unique free-living species have been described, and the potential number of extant species is estimated at 27,000–40,000. Included in this number are many ectosymbiotic and endosymbiotic species, as well as some obligate and opportunistic parasites. Ciliate species range in size from as little as 10 μm in some colpodeans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Pest Control
Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of integrated pest management (IPM) programs. There are three basic strategies for biological control: classical (importation), where a natural enemy of a pest is introduced in the hope of achieving control; inductive (augmentation), in which a large population of natural enemies are administered for quick pest control; and inoculative (conservation), in which measures are taken to maintain natural enemies through regular reestablishment. Natural enemies of insects play an important part in limiting the densities of potential pests. Biological control agents such as these include predators, parasitoids, pathogens, and com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invasive Species
An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food web. Since the 20th century, invasive species have become serious economic, social, and environmental threats worldwide. Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of invasion. For millennia, humans have served as both accidental and deliberate dispersal agents, beginning with their earliest migrations, accelerating in the Age of Discovery, and accelerating again with the spread of international trade. Notable invasive plant species include the kudzu vine, giant hogweed (''Heracleum mantegazzianum''), Japanese knotw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterias Amurensis
''Asterias amurensis'', also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleutian Islands and British Columbia in Canada. Two forms are recognised: the nominate and ''forma'' ''robusta'' from the Strait of Tartary. It mostly preys on large bivalve molluscs, and it is mostly preyed on by other species of starfish. Population booms in Japan can affect the harvest of mariculture operations and are costly to combat. This species has been introduced to oceanic areas of southern Australia, and is an invasive species there causing damage to native species, especially in Tasmania. Common names It is known in English vernacular as the northern Pacific seastar, flatbottom seastar, Japanese seastar, Japanese starfish, north Pacific seastar, purple-orange seastar and Japanese common starfish. Taxonomy This species was first describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity
Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distributed evenly on Earth. It is greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than one-fifth of Earth's terrestrial area and contain about 50% of the world's species. There are latitudinal gradients in species diversity for both marine and terrestrial taxa. Since Abiogenesis, life began on Earth, six major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic aeon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion. In this period, the majority of Multicellular organism, multicellular Phylum, phyla first appeared. The next 400 mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phagocytosis
Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte. In a Multicellular organism, multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris. The ingested material is then digested in the phagosome. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytized. Some protozoa use phagocytosis as means to obtain nutrients. The two main cells that do this are the Macrophages and the Neutrophils of the immune system. Where phagocytosis is used as a means of feeding and provides the organism part or all of its nourishment, it is called phagotrophy and is distinguished from osmotrophy, which is nutrition taking place by absorption. History The history of phag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptasterias
''Leptasterias'' is a genus of starfish in the Family (biology), family Asteriidae. Members of this genus are characterised by having six arms although five-armed specimens sometimes occur. ''L. muelleri'' is the type species. The taxonomy of the genus is confusing and ''Leptasterias hexactis'' seems to be a species complex. Some species brood their eggs. Description and biology ''Leptasterias'' is a genus of starfish in the family Asteriidae and order Forcipulatida. It is often noted that members in the genus have six arms, however, occasionally five-armed specimen can occur. They are also characterized by having several cryptic species complexes. They are often found in the waters of Alaska to central California in rocky intertidal and subtidal habitats. They are typically small in size, measuring less than 6 cm from ray tip to ray tip. They mature around the age of two. They are known for being lecithotrophic, providing the embryo with no nutrition other than the yolk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
