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Parorchis Acanthus
'' Parorchis acanthus'' is a parasitic flatworm of the class Trematoda. It is a parasitic castrator of the common periwinkle ''Littorina littorea''. Unlike many trematode species it encysts on hard surfaces and not inside a second intermediate host. Free-living cercariae are released from the snail hosts to encyst on hard surfaces, generally the shells of bivalves. The release is encouraged by warmer temperatures and increased light intensity. Encystment on bivalves is most successful when they enter the mussel with the inhalation current first. They then actively emerge, using their suckers and then encyst on the shell. If the bivalve is then eaten by a bird ''P. acanthus'' will be transmitted to the definitive host. Survival and successful encystment can be reduced by the presence of epibionts, such as the barnacle Semibalanus balanoides, on the shell. Castration of the snail molluscan host can result in a decline in host numbers and, in turn, can lead to more ungrazed alg ... [...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] |
Semibalanus Balanoides
''Semibalanus balanoides'' (common barnacle, common rock barnacle, northern rock barnacle) is a common and widespread boreo-arctic species of acorn barnacle. It is common on rocks and other substrates in the intertidal zone of north-western Europe and both coasts of North America. Description Adult ''S. balanoides'' grow up to in diameter, and are sessile, living attached to rocks and other solid substrates. They have six greyish wall plates surrounding a diamond-shaped operculum. The base of the shell is membranous in ''Semibalanus,'' unlike other barnacles which have calcified bases. When the tide rises to cover the barnacles, the operculum opens, and feathery ''cirri'' (modified thoracic appendages) are extended into the water to filter food from the seawater. When the tide falls, the operculum closes again to prevent desiccation; the reduction from the primitive condition of eight wall plates to six is believed to decrease water loss even further by reducing the number o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasites Of Molluscs
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is 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 honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism (by contact), trophicallytransmitted parasitism (by being eaten), vector-transmitted parasitism, parasitoidism, and micropredation. One major axis of classification concerns invasiveness: an endoparasite lives inside the host's body; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Rock Pipit
The European rock pipit (''Anthus petrosus''), or just rock pipit, is a species of small passerine bird that breeds in western Europe on rocky coasts. It has streaked greyish-brown upperparts and buff underparts, and is similar in appearance to other European pipits. There are three subspecies, of which only the Fennoscandian form is migratory, wintering in shoreline habitats further south in Europe. The European rock pipit is territorial at least in the breeding season, and year-round where it is resident. Males will sometimes enter an adjacent territory to assist the resident in repelling an intruder, behaviour only otherwise known from the African fiddler crab. European rock pipits construct a cup nest under coastal vegetation or in cliff crevices and lay four to six speckled pale grey eggs which hatch in about two weeks with a further 16 days to fledging. Although insects are occasionally caught in flight, the pipits feed mainly on small invertebrates picked off the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purple Sandpiper
The purple sandpiper (''Calidris maritima'') is a small shorebird in the sandpiper family Scolopacidae. This is a hardy sandpiper that breeds in the arctic and subarctic regions of Eurasia and North America and winters further south on the Atlantic coast. Taxonomy The purple sandpiper was formally described in 1764 by the Danish zoologist Morten Thrane Brünnich and given the binomial name ''Tringa maratina''. This species was formerly placed in the genus ''Erolia''. It is now placed with 23 other sandpipers in the genus ''Calidris'' that was introduced in 1804 by the German naturalist Blasius Merrem. The genus name is from Ancient Greek ''kalidris'' or ''skalidris'', a term used by Aristotle for some grey-coloured waterside birds. The specific epithet ''maritima'' is from Latin and means "of the sea", from ''mare'', "sea". The purple sandpiper is treated as monotypic: no subspecies are recognised. Within the genus ''Calidris'' the purple sandpiper is sister to the rock sandpipe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Littorina
''Littorina'' is a genus of small sea snails, marine gastropod molluscs in the family Littorinidae, the winkles or periwinkles.WoRMS (2011). Littorina Férussac, 1822. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138135 on 2011-04-15 These small snails live in the tidal zone of rocky shores. Overview In Europe there are about nine species in this genus, one of which is the rough periwinkle, ''Littorina saxatilis'' (Olivi, 1792). Another closely related (supposed) species ''Littorina tenebrosa'' (Montagu 1802) was thought to be distinct because of its different ecological requirements, but current studies have shown that it is not at all clear whether the two are indeed separate species or whether ''L. tenebrosa'' is perhaps merely an ecotype (an ecological form) of ''L. saxatilis''.Gosling, E.M. (2002). ''The periwinkle as a model in biodiversity studies: a geneticist's view.'' in Marine Biodiversity in Ireland and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelids, echinoderms and cnidarians. The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata. Invertebrates vary widely in size, from 50 μm (0.002 in) rotifers to the 9–10 m (30–33 ft) colossal squid. Some so-called invertebrates, such as the Tunicata and Cephalochordata, are more closely related to vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy. Etymology The word "invertebrate" comes from the Latin word ''vertebra'', whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as ''Chlorella,'' ''Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the ''Charophyta'', a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. No definition of algae is generally accepted. One definition is that algae "have chlorophyll ''a'' as their primary photosynthetic pigment and lack a sterile covering of cells around t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods ... [...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] |
Flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organ (anatomy), organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been prove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
