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An order of large brown algae (Phaeophyceae) commonly called kelps. Definitive features include a life history in which microscopic, filamentous, dioecious gametophytes alternate with a massive, parenchymatous sporophyte; growth of the sporophyte effected by meristems; and production of unilocular zoosporangia in extensive sori on blades of the sporophyte.
Industry:Science
An order of liverworts in the subclass Jungermanniidae, consisting of a single genus and two species: <i>Takakia lepidozioides</i> with the smallest chromosome number, 4, known in bryophytes, and <i>T. ceratophylla</i> (5 chromosomes).
Industry:Science
An order of liverworts in the subclass Jungermanniidae. Twelve families make up the Metzgeriales, which are also known as the Anacrogynae because of archegonia produced behind the growing apex. The gametophyte plant body is flat, elongated, and usually thallose, with no tissue differentiation or surface pores; less commonly there is a stem with two rows of leaves. The archegonia are generally protected by an involucre formed external to the calyptra and sometimes by additional structures. Capsules dehisce by valves.
Industry:Science
An order of liverworts in the subclass Marchantiidae, consisting of two families, the terrestrial Sphaerocarpaceae (<i>Sphaerocarpos</i> and <i>Geothallus</i>) and the aquatic Riellaceae (<i>Riella</i>). The plants are characterized by envelopes surrounding each antheridium and archegonium, absence of elaters, poor development of seta, and absence of thickenings in the unilayered wall of an indehiscent capsule.
Industry:Science
An order of liverworts of the subclass Marchantiidae, consisting of a single genus (<i>Monoclea</i>). The gametophyte is among the largest of all liverworts; its thallus consists of homogeneous cells except for scattered oil cells. The rhizoids are smooth and both thick-walled and thin-walled. The sex organs are grouped but not elevated: the antheridia are sunken in cavities and grouped into receptacles, while the archegonia are enclosed in groups by involucres. The very long, massive seta considerably elevates the capsules which dehisce spoonlike by one slit. The lobing of spore mother cells is unique in the subclass Marchantiidae.
Industry:Science
An order of liverworts. They are characterized by prostrate, simple or branched, leafless stems and erect, leafy branches of a radial organization. The order consists of a single genus, <i>Calobryum</i>, and 12 species, most of them occupying restricted ranges in apparently relic areas indicative of an ancient origin and dispersal. The order is considered primitive in comparison with the Jungermanniales, in which the leafy axis tends to be prostrate and the underleaves reduced.
Industry:Science
An order of lobefin fishes placed in the subclass Coelacanthimorpha and well known as fossils. Coelacanthiformes and the fossil suborders Rhizodontimorphi and Osteolepimorpha (rhipidistians) were once grouped as the subclass Crossopterygii. However, since it is now believed this assemblage is artificial, the coelacanth fraction was elevated to the subclass Coelacanthimorpha, with one order (Coelacanthiformes), four fossil families, and one extant family (Coelacanthidae).
Industry:Science
An order of Lobosia. The shell (test) of these protozoa has a single, well-defined aperture through which slender fingerlike pseudopodia (lobopodia) can be extended. The test often has an internal chitinous layer known as a glycocalyx and an external layer composed of secreted siliceous elements, organic hollow platelets, or collected sand grains and other matter cemented together by an adhesive secretion. The secreted platelets are synthesized within membranous vesicles in the cytoplasm, where they first appear as dense granules. These granules are transported to the surface of the cell, where they are deposited on the outer surface of the cell membrane and mature into the alveolate, closely assembled platelets.
Industry:Science
An order of mammals closely related to elephants. Hyracoids were a diverse and successful group of mammals in Africa during the Eocene and Oligocene epochs (early part of the Age of Mammals, 55 to 34 million years ago), and they are still represented by a few living species. The early hyracoids ranged from animals as small as rabbits to ones as large as modern Sumatran rhinoceroses. The fossil skeletons of the early hyracoids indicate that some species were active runners and leapers, while others were heavy, piglike quadrupeds. Their teeth suggest herbivorous diets, ranging from fibrous leaves in some species to pulpy fruits and roots in others. Hyracoids originated in Africa but later extended their range into Europe and Asia, eventually attaining a distribution encompassed by China, Spain, and South Africa. In contrast to the early diversity of the order, the only living species are a few small-bodied animals (1.5–5.5 kg or 3.3–12 lb) that inhabit forests, scrubby brushlands, and rocky deserts in Africa and the Middle East. Hyracoidea represents a classic case of a spectacular adaptive radiation on an isolated continent, now reduced to a few remnant living taxa.
Industry:Science
An order of mammals composed of two living families: Leporidae (rabbits and hares) and Ochotonidae (pikas). Rabbits and hares have short tails and long ears, whereas pikas lack an external tail and are short-eared. Rabbits and hares occupy a wide variety of habitats and are nearly worldwide in distribution. Pikas are found only in the mountains of western North America, in Siberia, and in the Himalayan region.
Industry:Science
