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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A class of terrestrial fungi in the phylum Zygomycota, reproducing sexually with a zygospore and asexually by sporangiospore or conidium. The Zygomycetes are one of two classes of the phylum Zygomycota, the other being the arthropod-associated Trichomycetes. Zygomycetes can be distinguished by the production of sporangia (sacs) that undergo internal cleavage to produce multiple sporangiospores (see <b>illustration</b>) as opposed to the production of conidiospores as observed in most other groups of fungi (Ascomycota and Basidiomycota). A notable exception is the order Entomophthorales, which reproduces asexually by conidium formation. Zygomycetes are all microscopic with the exception of <i>Endogone</i> and relatives that produce a zygospore containing structure called a sporocarp. Zygomycetes are typically studied by first isolating them into pure culture on nutrient media. Sexual reproduction results in the formation of a thick-walled zygosporangium following the conjugation of morphologically relatively similar, undifferentiated gametangia (single-cell structures functioning as gametes). The gametangia may be derived from different (heterothallism) or the same (homothallism) thallus, or genetic individual.
Industry:Science
A class of terrestrial, tracheate, oviparous arthropods. Diplopods (millipeds) are largely cryptic in habits, are saprophytic feeders, and are characterized by the development of a compact head with a pair of short, simple, eight-jointed antennae, powerful mandibles, and a subbuccal gnathochilarium formed from embryonic maxillary elements. The body is not differentiated into thorax and abdomen, but is composed of a variable number of similar, cylindrical diplosomites, each of which (except the first two or three) bears two pairs of walking legs (see <b>illus.</b>). The body wall is chitinous, with a thick impregnation of calcium carbonate in the majority of species. Most millipeds are variously adapted for rolling into a closed spiral or nearly perfect sphere when threatened. Typically, each abdominal segment is provided with a pair of glands which effuse a volatile poisonous fluid. Respiration occurs through profuse fine tracheae opening through stigmata near the bases of the legs. The digestive tract is a straight tube, except in oniscomorph species in which it is somewhat coiled. The anal opening is in the last segment and is closed by two tightly fitting anal valves. Ducts from reproductive organs pass through or behind the second pair of legs to external openings.
Industry:Science
A class of the Asterozoa, known as the brittle stars, in which the arms are usually clearly demarcated from a central disk and perform whiplike locomotor movements, and the tube feet are nonsuctorial sensory tentacles. In all existing ophiuroids the ambulacral plates fuse together in pairs to form articulating joints termed vertebrae, and the ambulacral groove is converted into an internal epineural canal.
Industry:Science
A class of the division Cycadophyta consisting of a single order, Cycadales, dating back to the Triassic and most abundant in the Jurassic. There are 100–150 living species of cycads in two families, Cycadaceae with one genus and Zamiaceae with ten genera. Most cycads are tropical, but some extend into warm temperate regions. Wild cycads are threatened by collection for horticulture so are protected by international treaties. They were used as traditional foods in some places but contain potent carcinogens and neurotoxins.
Industry:Science
A class of the Myriapoda commonly known as the centipedes. As are all myriapods, centipedes are ground dwellers whose permeable cuticle largely restricts their distribution to moist sites and habitats. Centipedes are mostly found under stones, in moss cushions, in leaf litter, and beneath loose bark on trees; several species inhabit caves, especially those of temperate regions. All centipedes are carnivorous; their predatory habits are reflected in their great agility and fleetness and especially in the modification of the first trunk appendages into a pair of usually massive raptorial pincers, the poison claws (also called the forcipules or the prehensors). Each poison claw contains a poison gland whose duct opens near the tip of the claw. Exceptionally, the poison gland may be located in the trunk, in which case the duct connecting it to the apical opening can be as long as twenty body segments. The poison immobilizes or kills arthropod prey and even some small vertebrates. The bite of larger species, particularly of the Scolopendromorpha, may be painful to human beings, but no serious consequences have been reported.
Industry:Science
A class of the Myriapoda. Pauropods are small creatures, 0.3–2.0 mm (0.012–0.08 in.) in length, whitish or brownish in color, that inhabit moist soil and the lower litter layer. They also can be found under bark and moss. Adults have 8–11 pairs of legs and unique forked antennae. The head and tergites (dorsal plates covering the somites) of Pauropoda are provided with setae or protuberances that vary considerably in shape. They can be filiform (filament-like or thread-like), shield-like, globular, or tuft-like. Superficially, pauropods may resemble insects, such as collembolans, but they have a diverging and distinctive locomotory pattern. They can elongate their body or shorten it by contraction to a very high degree. They also are swift, with their movements characterized by rapid rushes and frequent abrupt changes in direction.
Industry:Science
A class of the Myriapoda. The symphylans, like the pauropods, are tiny, pale, centipedelike creatures that inhabit humus or soil, or live under debris; in general, they live wherever there is sufficient moisture to preclude excessive water loss. They are similar to the Pauropoda and Diplopoda in being progoneate (having reproductive tracts open at anterior end of body) and anamorphic (gradually increasing in complexity of form and function). Each of their mandibles, like those of millipedes, but unlike the simple pauropod mandible, bears a movable gnathal lobe; at the same time their two pairs of maxillae are more reminiscent of the chilopods and lower insects than of the singly maxillate millipedes and pauropods. Additional signal characteristics include the following: The antennae are unbranched and simple; there is 1 pair of spiracles arising in the head and opening into tracheae; there are 12 pairs of legs, 1 pair per body segment; most of the legs have peculiar basal eversible vesicles with associated styli: the tergites number at least 15 and do not form diplotergites; there is a prominent pair of terminal spinnerets.
Industry:Science
A class of the phylum Arthropoda, sometimes called the Hexapoda. In fact, Hexapoda is a superclass consisting of both Insecta and the related class Parainsecta (containing the springtails and proturans). Class Insecta is the most diverse group of organisms, containing about 900,000 described species (see <b>table</b>), but there are possibly as many as 5 million to perhaps 20 million actual species of insects. Like other arthropods, they have an external, chitinous covering. Fossil insects dating as early as the Early Devonian have been found.
Industry:Science
A class of the phylum Ascomycota that includes the yeasts and yeastlike fungi. These are morphologically simple fungi; no ascoma is formed, and the asci are produced free on the host or substrate. Asexual reproduction occurs by the formation of blastospores (budding) or, less frequently, by fission arthrospores. Two main orders are recognized, the Saccharomycetales and the Taphrinales.
Industry:Science
A class of the phylum Bryozoa. Phylactolaemates have lophophores (crowns of tentacles surrounding the mouth) which are markedly U-shaped (or rarely nearly circular but still kidney-shaped) in basal outline, and relatively short wide zooecia (exoskeletal living chambers); these animals dwell only in freshwater.
Industry:Science
