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Pagurus Dalli
''Pagurus dalli'', commonly known as the whiteknee hermit, is a species of hermit crab in the family Paguridae. It is found in the northeastern Pacific Ocean at depths down to about . It usually lives in a mutualistic symbiosis with a sponge, or sometimes a hydroid. Description ''Pagurus dalli'' has a smooth, partially calcified carapace up to long, and a curved abdomen. The legs are light tan with white stripes, and it is the broad white band on the merus segment of the chelae (claws) that gives this hermit crab its common name. The dorsal surface of the carapace has a network of white, red, light and dark brown markings and is rimmed with red, and the flagellae (terminal segments) of the second pair of antennae are reddish-brown and white. Distribution This hermit crab is native to the northeastern Pacific Ocean, its range extending from the Bering Sea to Oregon, but is not particularly common anywhere. Its depth range is from the low intertidal zone to a depth of ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The United States National Museum
The Smithsonian Contributions and Studies Series is a collection of serial periodical publications produced by the Smithsonian Institution, detailing advances in various scientific and societal fields to which the Smithsonian Institution has made contributions. History The Smithsonian Institution began publishing consolidated compilations of quarto-sized papers in 1848, under the name ''Smithsonian Contributions to Knowledge''.History of Scholarly Publishing , ''''. In 1862 octavo
Octavo, a Latin word m ...
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Suberites Ficus
''Suberites ficus'' is a species of sponge in the family Suberitidae. It is sometimes known as the sea orange sponge. Sponges are primitive animals with little apparent internal organisation. They are composed of a jellylike mesohyl sandwiched between two layers of cells and have a fragile skeleton composed of stiff spicules. They are filter feeders, maintaining a flow of water through their structure which passes out through large openings called oscula. Taxonomy The name "ficus" was first used by Pallas in 1766 for ''Alcyonium ficus'' but it is unclear exactly which animal he was describing and it is now thought that it may have been an ascidian. Linnaeus in 1767, Esper in 1794 and Lamarck in 1814 also used the name but it was not until Johnston described the spicules as well as the sponge which he named ''Halichondria ficus'' in 1842 that it became clear what sponge was being described. Further research needs to be undertaken to clarify the position. ''Suberites suberia' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes are haploid cells. Some hermaphroditic animals have a type of gonad called an ovotestis. Evolution It is hard to find a common origin for gonads, but gonads most likely evolved independently several times. Regulation The gonads are controlled by luteinizing hormone and follicle-stimulating hormone, produced and secreted by gonadotropes or gonadotrophins in the anterior pituitary gland. This secretion is regulated by gonadotropin-releasing hormone produced in the hypothalamus. Development Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of genital ridges, which ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitism
Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as Armillaria mellea, honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the Orobanchaceae, broomrapes. There are six major parasitic Behavioral ecology#Evolutionarily stable strategy, strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism (by contact), wikt:trophic, trophicallytransmitted parasitism (by being eaten), Disease vector, vector-transmitted paras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyprid
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic (active swimming) larval stages. Around 1,000 barnacle species are currently known. The name is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Description Barnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale (whale barnacles), a sea snake (''Platylepas ophiophila''), or another crustacean, like a crab or a lobster (Rhizocephala). The most common among them, "acorn barnacles" (Sessilia), are sessile where they grow their shells directly onto the substrate. Pedunculate ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Host (biology)
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms (e.g. nematodes), cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner. Symbiosis Symbiosis spans a wide variety of possible relationships between organisms, differing in their permanence and their effects on the two parties. If one of the partners in an association is much larger than the other, it is generally known as the host. In parasitism, the parasite benefits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clistosaccus
''Clistosaccus'' is a genus of barnacles which are parasitic on hermit crabs. It is a monotypic genus, and the single species is ''Clistosaccus paguri'', which is found in the northern Atlantic Ocean and the northern Pacific Ocean. Taxonomy In his 1861 paper, Wilhelm Lilljeborg described two new monotypic genera, ''Apeltes'' (with the species ''A. paguri'') and ''Clistosaccus'' (with ''C. paguri''), both collected from ''Pagurus'' hermit crabs. It was not until the 1920s that Hilbrand Boschma pointed out these two purported species, at the time placed in separate families, were but two distinct growth stages of the same organism and united them under ''Clistosaccus''. Description This parasitic barnacle starts life as an internal parasite in the abdomen of its host hermit crab. After about three months a protuberance, known as an "externa", pushes its way through the abdomen, usually on the left side. This bulge is at first globular, but elongates as it grows, becoming cylindric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnacle
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic (active swimming) larval stages. Around 1,000 barnacle species are currently known. The name is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Description Barnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale (whale barnacles), a sea snake ('' Platylepas ophiophila''), or another crustacean, like a crab or a lobster ( Rhizocephala). The most common among them, "acorn barnacles" ( Sessilia), are sessile where they grow their shells directly onto the substrate. Peduncul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomura
Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word ''crab'', all true crabs are in the sister group to the Anomura, the Brachyura (the two groups together form the clade Meiura). Description The name Anomura derives from an old classification in which reptant decapods were divided into Macrura (long-tailed), Brachyura (short-tailed) and Anomura (differently-tailed). The alternative name Anomala reflects the unusual variety of forms in this group; whereas all crabs share some obvious similarities, the various groups of anomurans are quite dissimilar. The group has been moulded by several instances of carcinisation – the development of a crab-like body form. Thus, the king crabs (Lithodidae), porcelain crabs (Porcellanidae) and hairy stone crab (Lomisidae) are all separate instances of carcinisation. As decapods (meaning ''ten-legged''), anomurans have ten pereiopods, but the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octopus
An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight limbs. The soft body can radically alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates. Octopuses inhabit various regions of the ocean, including coral reefs, pelagic waters, and the seabed; some live in the intertidal zone and others at abyssal depths. Most species grow quickly, mature earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schuchertinia Milleri
''Schuchertinia milleri'', commonly known as the Miller hydractinia, hedgehog hydroid or snail fur, is a small colonial hydroid in the family Hydractiniidae, found in the eastern Pacific Ocean. It forms mat-like colonies on rocks, or sometimes on the mollusc shells occupied by hermit crabs. Taxonomy Harry Beal Torrey described the species in the much larger genus ''Hydractinia'' in 1902. That placement remained unchallenged for over a century until phylogenetic studies began to be carried on the Hydractiniidae, which revealed that ''Hydractinia'' required splitting. ''H. milleri'' was amongst the species transferred to the newly erected '' Schuchertinia'' in 2010. Description Colonies of this hydroid consist of a carpet-like mat of stolons, interspersed with long spines, from which arise singly three different types of polyp; feeding polyps known as gastrozooids, reproductive polyps known as gonozooids and finger-shaped polyps known as dactylozooids. The stolons have a chitino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the battledress of a modern soldier, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate, as well as making general aiming easier. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration, eliminating shadow, and countershading. In the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the bioluminescence, ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chamel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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