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An order of Protozoa of the class Haplosporea which comprises parasites in skeletal and cardiac muscle of vertebrates. The organisms have a very wide distribution both geographically and in host species, infecting reptiles, birds, and mammals (including marsupials). Humans are occasionally infected by the parasite referred to as <i>Sarcocystis lindemanni.</i> It is doubtful whether Sarcosporida found in different hosts are themselves always different, though this has often been assumed. Host specificity is known not to be strict; however, it is unlikely that there is only one species—<i>S</i>. <i>miescheriana</i>—as proposed by some investigators.
Industry:Science
An order of protozoans, subclass Holotrichia, in which all species are mouthless. All species are parasitic in other animals, typically oligochaete annelids. Many astomatids possess an elaborate holdfast organelle, of value in attachment to the cells or tissues of the host's alimentary tract. Some authorities have considered the species of this rather large and ill-defined group to represent nothing more than degenerate, astomatous members of certain other groups, such as thigmotrichs, apostomes, and possible hymenostomes. Still, there seems to be value in recognizing the evolutionary distinctiveness of the group as a whole. <i>Anoplophyra</i> is a typical example.
Industry:Science
An order of rare arachnids comprising 21 known species from tropical and warm temperate regions. American species occur in Texas and California. All are minute, whitish, eyeless animals, varying from 0.03 to 0.11 in. (0.7 to 3 mm) in length, that live under stones, in caves, and in other moist, dark places. The elongate body terminates in a slender multisegmented flagellum set with setae. In a curious reversal of function, the pedipalps, the second pair of head appendages, serve as walking legs. The first pair of true legs, longer than the others and set with sensory setae, has been converted to tactile appendages which are vibrated constantly to test the substratum.
Industry:Science
An order of regular echinoids belonging to the Diadematacea, established for the two recognized species of <i>Micropyga</i>. They have an aulodont lantern with grooved teeth. Test plating is imbricate, and ambulacra are composed of trigeminate compound plates in which upper and lower elements are reduced to demiplates. Pore pairs are biserially arranged in ambulacral columns, and there are unique umbrellalike aboral tube feet. <i>Micropyga</i> is a deep-water echinoid, found between 480 and 4290 ft (150 and 1340 m) depth in the Indo-West Pacific. There are no fossils that can be placed in this taxon with certainty, but it is possible that the Upper Jurassic <i>Pedinothuria</i> may belong here.
Industry:Science
An order of Reptilia, subclass Synapsida, often called advanced mammallike reptiles, that flourished from the middle Permian through the Late Triassic. The group is highly diverse and subdivided into six suborders. Two of these, Eotitanosuchia and Dinocephalia, include relatively primitive mid-Permian carnivores and herbivores. A third, the Dicynodontia, made up of small to large herbivores, was abundant in the late Permian. Dicynodonts were associated with two carnivorous suborders, the Therocephalia and Gorgonopsia, which are morphologically intermediate between Eotitanosuchia and the cynodonts. Although these five developing lines are distinct, the skulls and skeletons in each became increasingly mammallike.
Industry:Science
An order of sharks (bramble sharks) represented by one family, one genus, and two species. The family (Echinorhinidae) differs from all other sharks in possessing the following combination of characters: body and fins covered with thornlike denticles; two small spineless dorsal fins placed posteriorly to the pelvic fin origin; anal fin lacking; minute spiracles placed well behind the eyes; teeth similar in both jaws; and caudal fin without a subterminal notch. Maximum length is 2 m (6.6 ft).
Industry:Science
An order of sharks comprising six families, 24 genera, and 97 species, commonly known as dogfish sharks. The order differs from all other sharks by the following combination of characters: two dorsal fins, with or without spines; no anal fin; spiracle behind eye; and lower nictitating eye membrane absent. For the most part, squaliform sharks inhabit continental and insular shelves and slopes, and sea mounts. Some species live at great depths. So far as known, squaliforms are ovoviviparous and produce from one to 22 pups per litter, depending on the species. The dwarf lantern shark (<i>Etmopterus perryi</i>), at 17 cm (6.7 in.) in length, probably is the world's smallest shark; the largest squaliform is the Pacific sleeper shark (<i>Somniosus pacificus</i>), which is up to 7 m (23 ft) in length. The diet consists of bony fishes, cephalopods, crustaceans and other invertebrates, mammals, and other sharks.
Industry:Science
An order of sharks distinguished from all other sharks by the following combination of characters: trunk cylindrical; head conical to cylindrical, not laterally expanded; two dorsal fins, lacking spines; five gill slits, all anterior to the pectoral fin base or the last two above the pectoral fin base; mouth large, its gape extending well beyond the eyes; spiracles usually present, small and well behind the eyes; eyes without a nictitating membrane; barbels absent; and ring-type intestinal valve. Lamniform sharks are ovoviviparous. Fertilized eggs are enclosed in egg cases in the oviducts (uteri), where they undergo embryonic development, ordinarily from the energy supplied by the yolk. Although the reproductive event may begin with each uterus containing about 20 fertilized eggs, normally only one or two in each uterus reach full term. The gross loss of potential progeny is explained by oophagy or uterine cannibalism, an uncommon phenomenon in which the largest (and presumably oldest) fetuses are free in the uterus to feed on the remaining eggs and developing embryos, thus cannibalizing their potential siblings. This reproductive strategy sacrifices numbers for a few large, strong pups that are like small adults, ready to fend for themselves.
Industry:Science
An order of small copepod Crustacea. The abundant fresh-water and salt-water species form an important link in the food chains of aquatic life, consuming tiny plants, animals, and detritus and, in turn, furnishing food for small fish, some large fish, and other organisms. Some species are important intermediate hosts for human parasites. Females of the family Ergasilidae are parasitic on aquatic animals, while the males are free-swimming.
Industry:Science
An order of small wingless insects, permanently parasitic on mammals and birds. The Phthiraptera are one of approximately 30 major groups of insects and can be divided into four suborders, three of which (the Amblycera, Ischnocera, and Rhynchophthirina) are known as chewing or biting lice, and the fourth (the Anoplura) as sucking lice. Amblycera and Ischnocera are found on both mammals and birds, whereas species of Rhynchophthirina and Anoplura are confined to mammals. In total there are approximately 5000 known species, of which just under 70% are recorded from a single host species.
Industry:Science
