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Platyceratoidea
Platyceratidae is an extinct family of Paleozoic sea snails, marine gastropod mollusks. This family may belong in the Patellogastropoda or the Neritimorpha. Platyceratids are known for the complex symbiotic relationships they had with crinoids. Platyceratids are thought to have been parasitic on crinoids, either drilling into the stomach to steal the crinoid's food in a form of kleptoparasitism or drilling into the anal sac to feed on the gonads or the hindgut. Previous authors have suggested that platyceratids were commensalists which fed on crinoid fecal matter without harming the crinoid, but more recent studies have shown that platyceratids did have a negative effect on their crinoid hosts as would be expected if they were actively parasitic. It has been suggested that the large spines present on many species of crinoids served to deter predators who might damage or harm the crinoid in an effort to feed on the platyceratid snails infesting it. This is the only family in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platyceras
''Platyceras'' is a genus of extinct Paleozoic sea snails, marine gastropod mollusks in the family Platyceratidae. This genus is known from the Silurian to the Middle Triassic periods and especially abundant in the Devonian and Carboniferous.Paleobiology Database''Platyceras''at Fossilworks.org It is the type genus of the family Platyceratidae. Description ''Platyceras'' has a distinctive, curved conical shape that is easily recognized. The cap-like shell is high and broad anteriorly. The posterior portion of the shell, at the apex, is usually slightly coiled in an asymmetrical fashion. Frequently, the front portions of the shells are broken, though the posterior sections are relatively well preserved. ''Platyceras'' is particularly abundant in Devonian deposits (359 million to 416 million years old). ''Platyceras'' and other platyceratid gastropods are known for the complex symbiotic relationships they had with crinoids.Baumiller T. K. (2003). "Evaluating the interaction betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeogeography, Palaeoclimatology, Palaeoecology
''Palaeogeography, Palaeoclimatology, Palaeoecology'' ("''Palaeo3''") is a peer-reviewed scientific journal publishing multidisciplinary studies and comprehensive reviews in the field of palaeoenvironmental geology. The journal is edited by T. J. Algeo, H. Falcon-Lang, P. Hesse, I. Montanez, J. Pike and S. Xie. It was established in 1965 and is currently published by Elsevier. Indexing and abstracting ''Palaeogeography, Palaeoclimatology, Palaeoecology'' is indexed and abstracted in the following databases: According to the ''Journal Citation Reports'', ''Advance in Space Research'' has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as i ... of 3.318. References External links * Biology journals Elsevier academic journals English-language journals Publi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Genus
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal family-group taxon is a nominal genus called the 'type genus'; the family-group name is based upon that of the type genus." Any family-group name must have a type genus (and any genus-group name must have a type species, but any species-group name may, but need not, have one or more type specimens). The type genus for a family-group name is also the genus that provided the stem to which was added the ending -idae (for families). :Example: The family name Formicidae has as its type genus the genus ''Formica'' Linnaeus, 1758. Botanical nomenclature In botanical nomenclature, the phrase "type genus" is used, unofficially, as a term of convenience. In the '' ICN'' this phrase has no status. The code uses type specimens for ranks up to fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commensalism
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit from each other; amensalism, where one is harmed while the other is unaffected; parasitism, where one is harmed and the other benefits, and parasitoidism, which is similar to parasitism but the parasitoid has a free-living state and instead of just harming its host, it eventually ends up killing it. The commensal (the species that benefits from the association) may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consistent with its habits, as in the remoras that ride attached to sharks and other fishes. Remo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonads
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 are only late ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kleptoparasitism
Kleptoparasitism (etymologically, parasitism by theft) is a form of feeding in which one animal deliberately takes food from another. The strategy is evolutionarily stable when stealing is less costly than direct feeding, which can mean when food is scarce or when victims are abundant. Many kleptoparasites are arthropods, especially bees and wasps, but including some true flies, dung beetles, bugs, and spiders. Cuckoo bees are specialized kleptoparasites which lay their eggs either on the pollen masses made by other bees, or on the insect hosts of parasitoid wasps. They are an instance of Emery's rule, which states that insect social parasites tend to be closely related to their hosts. The behavior occurs, too, in vertebrates including birds such as skuas, which persistently chase other seabirds until they disgorge their food, and carnivorous mammals such as spotted hyenas and lions. Other species opportunistically indulge in kleptoparasitism. Strategy Kleptoparasitism is a fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitic
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; an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crinoids
Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as . Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Hall (paleontologist)
James Hall Jr. (September 12, 1811 – August 7, 1898) was an American geologist and paleontologist. He was a noted authority on stratigraphy and had an influential role in the development of paleontology in the United States. Early life James Hall was born in Hingham, Massachusetts, the oldest of four children. His parents, James Hall Sr. and Sousanna Dourdain Hall, had emigrated from England two years earlier. Hall developed an early interest in science and enrolled in Rensselaer Polytechnic Institute, a recently established college that emphasized student participation and focused on science. He was a student of Amos Eaton and Ebenezer Emmons, both notable geologists. Hall graduated with honors in 1832, received his master's degree in 1833, and remained at Rensselaer to teach chemistry and later geology. In 1836 a multi-year survey was established to collect information on the geology and natural history of New York. For purposes of the survey, the state was divided into f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiotic
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, must be of different species. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms". The term was subject to a century-long debate about whether it should specifically denote mutualism, as in lichens. Biologists have now abandoned that restriction. Symbiosis can be obligatory, which means that one or more of the symbionts depend on each other for survival, or facultative (optional), when they can generally live independently. Symbiosis is also classified by physical attachment. When symbionts form a single body it is called conjunctive symbiosis, while all other arrangements are called disjunctive symbiosis."symbiosis." Dorland's Illustrated Medical Dictionary. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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