tag:blogger.com,1999:blog-75568441797208563512024-02-19T02:04:01.453-08:00Kids Research ExpressOnline Encyclopedia Blog For Kid's Research In Sciences, Health, Environment and Technologypiayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comBlogger139125tag:blogger.com,1999:blog-7556844179720856351.post-14672871168400474862013-07-18T07:22:00.004-07:002019-10-15T00:20:49.001-07:00Cattle<div style="text-align: justify;">
Cattle, name for the ruminant mammals of the genus Bos, and particularly those of the domesticated species, Bos taurus and B. indica. The term oxen, broadly used, refers also to closely related animals, such as the buffalo and the bison. Narrowly used, ox refers to a mature castrated male used for draft purposes. In referring to domestic cattle a grown male is a bull, a grown female a cow, an infant a calf, and an animal between one and two years old a yearling. A female that has not given birth is a heifer; a castrated male is a steer.</div>
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Most cattle have unbranched horns consisting of a horny layer surrounding a bone extension of the skull; these horns, unlike those of deer, are not shed. Some cattle are naturally hornless. Western, or European, domestic cattle (Bos taurus) are thought to be descended mainly from the aurochs, a large European wild ox domesticated during the Stone Age, extinct since 1627. A smaller species, the Celtic shorthorn, was the most important domestic ox of the Stone Age and may also be involved in the ancestry of B. taurus. The zebu, or Indian ox, B. indica, is the humped domestic species of Asia and Africa. Several B. indica breeds have been developed in the United States into the Brahman breed. The yak, B. grunniens, and other cattle species, wild and domestic, exist in Asia. Domestic cattle were first brought to the Western Hemisphere by Columbus on his second voyage.</div>
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In various societies throughout history wealth has been measured in terms of cattle—cattle is related to capital and chattel, and pecuniary is derived from pecus [Lat.,=cattle]. Breeding for improvement of beef and dairy qualities, practiced by the Romans, was established on scientific principles in the middle of the 18th cent. by English livestock breeder Robert Bakewell (see animal husbandry; breeding). Important beef breeds include Angus, Hereford, Simmental, Charolais, Limousin, Gelbvieh, Brahman, and Shorthorn. Important crossbreeds include Brangus (Brahman x Angus) and Santa Gertrudis (Shorthorn x Brahman). Major dairy breeds include Holstein-Friesian, Jersey, Guernsey, Brown Swiss, Ayrshire, and Milking Shorthorn. The importance of dual-purpose breeds has declined.</div>
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Cattle are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Artiodactyla, family Bovidae. See also beef; dairying.</div>
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<i>Source: http://encyclopedia2.thefreedictionary.com/cattle</i></div>
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piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-1934661986781525022013-07-18T06:49:00.001-07:002013-07-18T06:49:39.240-07:00Mud Puppy<div style="text-align: justify;">
Mud puppy, common name for North American salamanders of the genus Necturus, found in rivers and streams throughout the E United States and SE Canada. The name derives from an erroneous belief that mud puppies bark. Like its relative, the European olm, the mud puppy exhibits neoteny, i.e., it reaches sexual maturity without losing its larval characteristics. Adults have lungs, characteristic of most adult salamanders, as well as gills, characteristic of larvae. Their short, sturdy limbs develop at an early stage. The mud puppy may reach a length of 12 in. (30 cm); it is reddish brown and black-spotted above and grayish below, with conspicuous bushy red gills at the sides of its head. It walks on river bottoms and feeds primarily on crayfish and aquatic plants. </div>
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Mud puppies are classified in the phylum Chordata, subphylum Vertebrata, class Amphibia, order Urodela, family Proteidae.</div>
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<i>Source: <a href="http://encyclopedia2.thefreedictionary.com/mud+puppies">http://encyclopedia2.thefreedictionary.com/mud+puppies</a></i></div>
piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-10216347218755447272013-07-18T06:46:00.001-07:002013-07-18T06:46:27.215-07:00Newt<div style="text-align: justify;">
Newt, name for members of a large salamander family, widely distributed in the Northern Hemisphere and including the common European salamanders. Newts are lizardlike in shape and are usually under 6 in. (15 cm) long including the slender tail. Some are brightly colored and secrete irritating substances. Like other salamanders, newts go through an aquatic, gilled larval stage. In some species the adults remain aquatic, although they lose their gills and breathe air; in others the adults are terrestrial, returning to water only to breed. Still other newts go through two adult stages: a terrestrial stage, during which they are called efts, is followed by a permanent aquatic stage. One such species is the common red-spotted newt (Diemictylus viridescens) of the E United States, known in its terrestrial stage as red eft. The 3-in. (7.5-cm) adult lays its eggs in spring on the stems and leaves of water plants. The greenish-brown larvae remain in the water for several months before emerging as efts, orange-red with a double row of black-ringed vermilion spots. The efts spend two or three years on land, hibernating in winter under leaves, and then return permanently to the water, becoming olive green and developing a broad swimming tail. </div>
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Newts are classified in the phylum Chordata, subphylum Vertebrata, class Amphibia, order Urodela, family Salamandridae.</div>
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<i>Source: <a href="http://encyclopedia2.thefreedictionary.com/newts">http://encyclopedia2.thefreedictionary.com/newts</a></i></div>
piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-8368430409975683832013-07-18T06:43:00.000-07:002013-07-18T06:43:51.745-07:00Salamanders<div style="text-align: justify;">
Salamander, an amphibian of the order Urodela, or Caudata. Salamanders have tails and small, weak limbs; superficially they resemble the unrelated lizards (which are reptiles), but they are easily distinguished by their lack of scales and claws, and by their moist, usually smooth skins. Salamanders are found in damp regions of the northern temperate zone and are most abundant in North America. Most are under 6 in. (15 cm) long, but the giant salamander of Japan (Megalobatrachus japonicus) may reach a length of over 5 ft (1.5 m). Most salamanders are terrestrial as adults, living near water or in wet vegetation, but some are aquatic and a few are arboreal, burrowing, or cave-dwelling. Most are nocturnal, and all avoid direct light. Salamanders are able to regenerate a lost limb or tail. They feed on small animals, such as insects, worms, and snails.</div>
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Most salamanders breed in water and are gregarious at breeding time, when there is usually a courtship display. In most species fertilization is internal. The male deposits sperm packets, which the female picks up with the cloaca; the sperm is then stored until fertilization takes place. The eggs, surrounded by gelatinous material, are usually laid in ponds or brooks, where they develop into aquatic larvae that can breathe by means of gills. A few salamanders breed on land, laying their eggs under rotting vegetation; the young pass through the gilled stage in the egg, emerging as miniature adults. Such strictly terrestrial forms are the red-backed salamander (Plethodon cinereus) and slimy salamander (P. glutinosus) of E United States and the slender salamander (Batrachoseps attenuatus) of the Pacific coast.</div>
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Most salamanders, including most that remain in an aquatic environment, go through a typical amphibian metamorphosis into air-breathing adults. Generally the adults have lungs, but in the large family of lungless salamanders (Plethodontidae) breathing occurs entirely through the skin and the lining of the throat. In a few salamanders growth occurs without metamorphosis, and the gilled, juvenile form is able to reproduce. This phenomenon (called neoteny) is found in the sirens (family Sirenidae) of S United States and N Mexico, in the mud puppies (family Protidae), and in the Mexican axolotl. </div>
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<i>Classification</i></div>
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<i>There are over 200 salamander species, classified in approximately 60 genera and 8 families of the phylum Chordata, subphylum Vertebrata, class Amphibia, order Urodela.</i></div>
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<i>Source: <a href="http://encyclopedia2.thefreedictionary.com/salamanders">http://encyclopedia2.thefreedictionary.com/salamanders</a></i></div>
piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-10720983716113802902013-07-18T06:38:00.000-07:002013-07-18T06:38:27.645-07:00Toad<div style="text-align: justify;">
Toad, name applied to certain members of the amphibian order Anura, which also includes the frog. Although there is no clear-cut distinction between toads and frogs, the name toad commonly refers to those species that have relatively short legs, stout bodies, and thick skins, and are less aquatic as adults than the long-legged, slender-bodied frogs.</div>
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Sometimes the term toad is restricted to the so-called true toads, members of the family Bufonidae. These are characterized by warty skins and prominent parotid glands behind the eyes and as a group are the most terrestrial of the order. In most the feet are only slightly webbed. They range in length from about 1 to 7 in. (2.5–18 cm). Most species belong to the genus Bufo; members of these species spend much of the time on land, generally near water. They generally live in cool, moist places and absorb moisture through the skin. The white fluid that they exude through the skin, as well as from the parotid glands, is very poisonous and causes intense burning if it comes in contact with the eyes or mouth; however, contrary to an old belief, it does not cause warts. Toads, like frogs, move on land by jumping and feed on insects and grubs. Also like frogs, they usually lay their eggs in water in strands of jelly. Fertilization is external. The egg hatches into a tadpole, a gilled, aquatic, larval toad that undergoes metamorphosis into the adult.</div>
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There are about a dozen Bufo species in the United States, among them the common American toad (Bufo americanus), Fowlers toad (B. fowleri), of the E United States, and the red-spotted toad (B. punctatus), of the Southwest. The cane, marine, or giant toad (B. marinus), a large toad native to Central and N South America, was widely introduced in warm regions (Caribbean, Pacific, Australia, and Florida) to control agricultural pests but is now regarded as an invasive species; they compete with and prey on native species, and their toxic secretions can kill predators.</div>
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The spadefoot toads, burrowing toads of the family Pelobatidae, are represented in the United States by several species of the genus Scaphiopus. Toads are classified in the phylum Chordata, subphylum Vertebrata, class Amphibia, order Anura.</div>
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<i>Source: <a href="http://encyclopedia2.thefreedictionary.com/Toads">http://encyclopedia2.thefreedictionary.com/Toads</a></i></div>
piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-58165744418037709652013-07-18T06:32:00.000-07:002013-07-18T06:32:37.899-07:00Caecilians<div style="text-align: justify;">
Caecilian (sēsĭl`ēən), any of the legless, tailless tropical amphibians belonging to the order Gymnophiona (or Apoda). Most adult caecilians resemble earthworms superficially but have vertebrate characteristics such as jaws and teeth.</div>
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Caecilians range in size from 7 in. to 4.5 ft (18 cm–140 cm); most are about 1 ft (30 cm) long. Their bodies are ringed with grooves, which in some species contain small scales imbedded in the skin; possession of scales is a primitive amphibian trait. There is a groove on either side of the head, each containing a retractable sensory tentacle. The eyes of caecilians are nearly functionless, and some species are eyeless.</div>
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Caecilians are found in swampy places in most tropical parts of the world, but are seldom seen because of their burrowing behavior. They eat small invertebrates such as termites and earthworms. A few species remain aquatic as adults and resemble eels.</div>
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There are more than 180 species of caecilians, divided into 10 families. They are classified in the phylum Chordata, subphylum Vertebrata, class Amphibia, order Gymnophiona (or Apoda).</div>
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<i>Source: <a href="http://encyclopedia2.thefreedictionary.com/caecilians">http://encyclopedia2.thefreedictionary.com/caecilians</a></i></div>
piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.comtag:blogger.com,1999:blog-7556844179720856351.post-79977576257501059012011-02-19T18:01:00.000-08:002011-02-19T18:01:37.181-08:00Chimpanzee<div style="text-align: justify;">Chimpanzee, an ape, genus Pan, of the equatorial forests of central and W Africa. The common chimpanzee, Pan troglodytes, lives N of the Congo River. Full-grown animals of this species are up to 5 ft (1.5 m) tall and weigh about 150 lb (68 kg); they have an arm spread of up to 9 ft (2.7 m) and are much stronger than humans. They are covered with long, black hair over most of the body and have naked faces ranging in color from nearly white to nearly black. The pygmy chimpanzee, P. paniscus, now usually called the bonobo, lives south of the Congo. It is a bit smaller and more slenderly built, with a black face.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Chimpanzees spend much time on the ground, where they walk on all fours, using the soles of the feet and the knuckles of the hands; they can also stand on two legs and sometimes walk this way for short distances. They climb trees in pursuit of food and for nesting and can swing by their hands from branch to branch. Their diet consists largely of fruit and other plant matter, but they also hunt and eat small animals, including monkeys. They use and even make primitive tools; for example, they collect termites using twigs and crack nuts using stones. Many primatologists now attribute culture to chimpanzees, noting learned variations in such skills and habits among different groups.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Chimpanzees move about the forest in bands of varying composition, usually numbering six to ten individuals. The males of a group engage in dominance contests involving much screaming and stamping. Family groups consist of mothers and offspring; females mate with many males during their fertile periods. A single infant is born every three to eight years; young chimpanzees ride about on their mothers' backs. Under ideal circumstances chimpanzees may live 50 years.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Although incapable of speech beyond their own simple vocalizations, captive chimpanzees have been taught to communicate in a language using visual rather than verbal symbols. Because of their close evolutionary relationship to humans they are often used for medical and behavioral experimentation, but the degree to which chimpanzees and humans are genetically close is a subject of dispute, with estimates of the amount of DNA the species share ranging from 94.6% to 99.4%. Chimpanzees, especially bonobos, are considered endangered species because of hunting and loss of habitat.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Chimpanzees are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, family Pongidae.</div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-12368886843893714372011-02-19T17:57:00.000-08:002011-02-19T17:57:26.399-08:00Insect<div style="text-align: justify;">Insect, invertebrate animal of the class Insecta of the phylum Arthropoda. Like other arthropods, an insect has a hard outer covering, or exoskeleton, a segmented body, and jointed legs. Adult insects typically have wings and are the only flying invertebrates.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The body of the typical adult insect is divided into three distinct parts, the head, thorax, and abdomen. The head bears three pairs of mouthparts, one pair of compound eyes, three simple eyes (ocelli), and one pair of jointed sensory antennae. The thorax is divided into three segments, each with a pair of jointed legs, and bears two pairs of wings. The abdomen has posterior appendages associated with reproduction. The exoskeleton is composed of a horny substance called chitin.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Insects breathe through a complex network of air tubes (tracheae) that open to the outside through a series of small valved apertures (spiracles) along the sides of the body. In chewing insects the digestive system includes a muscular gizzard that is lacking in sucking insects. The simple circulatory system is composed of a tubular heart that pumps blood forward into the head, from which it diffuses through the tissues and back into the heart. The aquatic larvae of many insects breathe by means of external gills; some very primitive species breathe directly through the body wall.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Insect Species</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">There are about 900,000 known insect species, three times as many as all other animal species together, and thousands of new ones are described each year. They are commonly grouped in 27 to 32 orders, depending upon the classification used. The largest order is that of the beetles (Coleoptera). Next, in order of size, are the moths and butterflies (Lepidoptera); the wasps, ants, and bees (Hymenoptera); and the flies and mosquitoes (Diptera). Other major orders are the true bugs (Hemiptera); the cicadas, aphids, and scale insects (Homoptera); the grasshoppers and crickets (Orthoptera); the cockroaches (Blattodea); and the mantids (Mantodea).</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Insects are found throughout the world except near the poles and pervade every habitat except the sea (although there is one marine species of water strider). Fossil records indicate that many species exist today in much the same form as they did 200 million years ago. Their enormous biological success is attributed to their small size, their high reproductive rate, and the remarkable adaptive abilities of the group as a whole, shown by the enormous variety in body structure and way of life. The mouthparts may be adapted to chewing, sucking, piercing, or lapping and the legs for walking, running, jumping, burrowing, or swimming. Insects may feed on plants or decaying matter or prey upon other small animals (especially other insects) or parasitize larger ones; they may be omnivorous or highly specialized in their diets. They display a remarkable variety of adaptive shapes and colors that may serve either as camouflage or as warning (see mimicry). Some have stinging spines or hairs and blistering or noxious secretions, used for defense.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Reproduction</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">A few species, notably the fireflies, produce light, used as a signal in courtship, by a chemical reaction. The sexes are separate in insects, and reproduction is usually sexual, although in many insect groups eggs sometimes develop without fertilization by sperm (see parthenogenesis). In some insects, such as bees, unfertilized eggs become males and fertilized eggs females. In others, such as aphids, all-female generations are produced by parthenogenesis. Eggs are usually laid in a sheltered place; in a few insects they are retained and hatched internally. After hatching, the insect must molt periodically as it grows, since the rigid exoskeleton does not allow much expansion. A new, soft exoskeleton forms beneath the old one, and after each molt the insect undergoes a rapid expansion before its new covering hardens. The stages between molts are called instars; the final instar is the adult.</div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-12500310604021051932011-02-19T17:17:00.000-08:002011-02-19T17:17:06.162-08:00Trilobite<div style="text-align: justify;">Trilobite (trī`ləbīt'), subphylum of the phylum Arthropoda that includes a large group of extinct marine animals that were abundant in the Paleozoic era. They represent more than half of the known fossils from the Cambrian period. The trilobite body was generally oval and flat and was divided into three roughly equal sections: the head, thorax, and tail. The name trilobite refers to a pair of furrows along the length of the animal that divided the body into three longitudinal regions. The body was covered by a mineralized shell. Because the dorsal, or upper, shell was thicker than the under shell, it has been the part best preserved in fossil form. Trilobites were abundant inhabitants of the Cambrian and Ordovician geological periods. They declined thereafter, possibly because they became food for cephalopods and later for fish, and became extinct in the Permian period. Trilobites are most closely related to the chelicerates, which include the horseshoe crabs and spiders.</div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-40118519948166235802011-02-19T17:14:00.000-08:002011-02-19T17:14:16.192-08:00Mastodon<div style="text-align: justify;">Mastodon (măs`tədŏn'), name for a number of prehistoric mammals of the extinct genus Mammut, from which modern elephants are believed to have developed. The earliest known forms lived in the Oligocene epoch in Africa. These were long-jawed mastodons about 4 1-2 ft (137 cm) high, with four tusks and a greatly elongated face. Their descendants in the Miocene epoch were the size of large elephants, the latest forms having long, flexible trunks, like those of elephants, and only two tusks. During Miocene times they spread over Europe, Asia, and North America. The mastodons were forest dwellers; they obtained their food by browsing and their teeth were more numerous and of a simpler form than those of the elephant. They were apparently extinct in the Old World by the early Pleistocene epoch but survived in North America until late Pleistocene times. They are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Proboscidae, family Mammutidae.</div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-36685686991452249452011-02-19T17:10:00.000-08:002011-02-19T17:10:37.406-08:00SpeciesSpecies, in biology, a category of classification, the original and still the basic unit in the demarcation of plant and animal types. The species marks the boundary between populations of organisms rather than between individuals. Because related species are not absolutely permanent (see evolution), a precise definition of the term is difficult. On the basis of genetics, scientists now include in a species all individuals that are potentially or actually capable of interbreeding and that share the same gene pool. The latter term refers to that collection of characteristics whose combination is unique in the species, although each individual of the group may not display every single one of the characteristics (see genetics). In the few cases where members of different species can interbreed, the offspring are usually sterile (e.g., the mule). Groups distinguished by lesser differences than those marking a species are called variously subspecies, varieties, races, or tribes.<br />
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See: <a href="http://kidsresearchexpress.blogspot.com/2008/08/species-and-speciation.html">Species and Speciation</a>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-37767256783770289232011-02-19T17:01:00.001-08:002011-02-19T17:01:50.655-08:00Mammoth<div style="text-align: justify;">Mammoth, name for several large prehistoric elephants of the extinct genus Mammuthus, which ranged over Eurasia and North America in the Pleistocene epoch. The shoulder height of the Siberian, or woolly, mammoth, which roamed throughout the Northern Hemisphere, was about 9 ft (2.7 m), and that of the imperial mammoth of the North American Great Plains was up to 13 1-2 ft (4.1 m). Mammoths were covered by a long, shaggy, black outer coat and a dense, woolly undercoat. They had complex, many-ridged molar teeth; long, slender upward-curved tusks; and a long trunk. Ivory hunters have collected their tusks for centuries in Siberia, where some 50,000 have been discovered; it is from these and from the drawings left by the Cro-Magnon people in the caves of S France that the mammoth's appearance is known. Paleolithic (Old Stone Age) people hunted mammoths, as is evidenced by remains of the animals found together with tools, and may have contributed to their extinction. Mammoths are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Proboscidea, family Elephantidae.</div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-57325277684853994282010-10-09T19:47:00.000-07:002010-11-24T21:50:25.569-08:00Photos of Mammals<div align="justify"><span style="color: white;">.</span></div><div align="justify"><a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1VnN2MI/AAAAAAAABfo/1QD3ol-5Sg8/s1600-h/Aardwolf.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244275556640217282" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1VnN2MI/AAAAAAAABfo/1QD3ol-5Sg8/s200/Aardwolf.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Aardwolf<br />
The aardwolf, a member of the hyena family, is found throughout southern and eastern Africa. Aardwolves travel at night hunting for food, which consists of carrion (dead and decaying animal flesh) and insects, usually termites. They have weak jaws and small teeth, leaving them without defenses against enemies such as dogs.<br />
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<a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1bflVQI/AAAAAAAABfw/BwbSzoZgpOY/s1600-h/Abyssinian.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244275558218814722" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1bflVQI/AAAAAAAABfw/BwbSzoZgpOY/s200/Abyssinian.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Abyssinian<br />
Abyssinians are particularly affectionate and have fine, soft fur resembling that of a wild rabbit. The origin of the cat is unknown, although its appearance suggests a relationship to the cats of ancient Egypt. It is one of the oldest breeds of domesticated cat.<br />
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<a href="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdo1rwpPDI/AAAAAAAABf4/lkAHIC3uZmg/s1600-h/Afghan+Hound.JPG"><img alt="" border="0" height="189" id="BLOGGER_PHOTO_ID_5244275562585340978" src="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdo1rwpPDI/AAAAAAAABf4/lkAHIC3uZmg/s200/Afghan+Hound.JPG" style="cursor: hand; float: left; height: 185px; margin: 0px 10px 10px 0px; width: 199px;" width="201" /></a>Afghan Hound<br />
The Afghan hound, similar to the greyhound, originated in Afghanistan and was known in ancient Egypt. A capable hunting dog, the Afghan hound is a swift runner and a powerful jumper.<br />
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<a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1qD0sQI/AAAAAAAABgA/YkW06lfJLQc/s1600-h/African+Elephants.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244275562128912642" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdo1qD0sQI/AAAAAAAABgA/YkW06lfJLQc/s200/African+Elephants.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>African Elephants<br />
African elephants live in grassy regions south of the Sahara Desert. Bull (male) elephants stand about 3.4 m (11 ft) tall and weigh about 5.4 metric tons, while cow (female) elephants stand 2.8 m (9 ft) tall and weigh about 3.6 metric tons. They have no sweat glands, so they like to cool off by rolling in ponds and streams. The mud that dries on their skin protects it from the sun.<br />
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<a href="http://2.bp.blogspot.com/_vZUSeG-88pw/SMdo1z8VGII/AAAAAAAABgI/cpzPlVXviAA/s1600-h/Agouti.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244275564781836418" src="http://2.bp.blogspot.com/_vZUSeG-88pw/SMdo1z8VGII/AAAAAAAABgI/cpzPlVXviAA/s200/Agouti.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Agouti<br />
A large rodent common to the forests of Central America and central-northern South America, the swift, ground-dwelling agouti feeds on leaves, roots, and fallen fruit. The agouti is hunted by farmers because it destroys crops in agricultural areas.<br />
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<a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpX3mDp9I/AAAAAAAABgQ/LYSXR9pp2Bg/s1600-h/Akhal-Tek%C3%83%C2%A9.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244276149877712850" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpX3mDp9I/AAAAAAAABgQ/LYSXR9pp2Bg/s200/Akhal-Tek%C3%A9.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Akhal-Teké<br />
A prized desert horse, the Akhal-Teké has been bred and raised for at least 3000 years, and may have been an ancestor of the Arabian. Remarkable endurance and resistance to heat give the powerful yet graceful Akhal-Teké an edge in competitive long-distance riding and show jumping.<br />
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<a href="http://3.bp.blogspot.com/_vZUSeG-88pw/SMdpX96WGPI/AAAAAAAABgY/wQcSNDQABnw/s1600-h/Alaskan+Malamute.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244276151573420274" src="http://3.bp.blogspot.com/_vZUSeG-88pw/SMdpX96WGPI/AAAAAAAABgY/wQcSNDQABnw/s200/Alaskan+Malamute.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Alaskan Malamute<br />
This Alaskan Malamute has dense, layered fur as a shield from severe weather. The nomadic Mahlemuts, an Inuit people of northwestern Alaska, first bred the Alaskan Malamute as a sled dog to haul their belongings. Ranging from light gray to black in color, Alaskan Malamutes are also popular as pets and show dogs.<br />
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<a href="http://3.bp.blogspot.com/_vZUSeG-88pw/SMdqQKMNPVI/AAAAAAAABgw/6JBalWtkdik/s1600-h/Alpine+Ibex.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244277116942237010" src="http://3.bp.blogspot.com/_vZUSeG-88pw/SMdqQKMNPVI/AAAAAAAABgw/6JBalWtkdik/s200/Alpine+Ibex.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Alpine Ibex<br />
Famous for its surefootedness in steep, rocky terrain, the Alpine ibex is one of four species of mountain goat in the genus Capra. The Alpine ibex was on the brink of extinction from overhunting and habitat destruction in the early 20th century, but is now protected and rebuilding herd populations in Italy’s Gran Paradiso National Park and other European wildlife preserves.<br />
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<a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpYOzSDbI/AAAAAAAABgg/mhODcYcW0rA/s1600-h/American+Black+Bear.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244276156107197874" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpYOzSDbI/AAAAAAAABgg/mhODcYcW0rA/s200/American+Black+Bear.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>American Black Bear<br />
The American black bear lives in forests throughout North America, from Alaska and Canada to mountains in northern Mexico. Unlike most other bear species, the American black bear has adapted to human encroachment on its habitat, and it is able to survive in populated suburban areas. Despite the bear’s common name, the color of the American black bear ranges from black to brown, cinnamon, beige, and even pure white.<br />
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<a href="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpYR3Ft1I/AAAAAAAABgo/q_yJBGFgrGY/s1600-h/Antarctic+Fur+Seal.JPG"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5244276156928472914" src="http://4.bp.blogspot.com/_vZUSeG-88pw/SMdpYR3Ft1I/AAAAAAAABgo/q_yJBGFgrGY/s200/Antarctic+Fur+Seal.JPG" style="cursor: hand; float: left; margin: 0px 10px 10px 0px;" /></a>Antarctic Fur Seal<br />
The Antarctic fur seal is one of 14 species of eared seals. Fur seals are polygamous and assemble in huge breeding colonies beginning in October. Breeding females feed exclusively on small, shrimplike crustaceans called krill, whereas males feed on krill, penguins, and fish. Although most eared seal populations have been decimated by overhunting, the Antarctic fur seal has rebounded from near extinction in the late 1800s to a current population of between 700,000 and 1 million animals.</div><div align="center"><strong><a href="http://kidsresearchexpress-8.blogspot.com/2008/09/pictures-of-mammals_09.html">more pictures</a></strong></div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-1147582596076785882009-04-15T22:50:00.001-07:002009-10-15T05:06:18.448-07:00Coral<a href="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdO5YHyWCI/AAAAAAAABcA/omDPNo6HHIY/s1600-h/Orange+tube-coral.JPG"><img id="BLOGGER_PHOTO_ID_5244247038730852386" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; WIDTH: 301px; CURSOR: hand; HEIGHT: 170px" height="172" alt="" src="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdO5YHyWCI/AAAAAAAABcA/omDPNo6HHIY/s320/Orange+tube-coral.JPG" width="302" border="0" /></a> <a href="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdRGhBhVhI/AAAAAAAABcY/S1ozoXpABEM/s1600-h/Branching+Coral+Colonies.JPG"><img id="BLOGGER_PHOTO_ID_5244249463482045970" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="http://1.bp.blogspot.com/_vZUSeG-88pw/SMdRGhBhVhI/AAAAAAAABcY/S1ozoXpABEM/s200/Branching+Coral+Colonies.JPG" border="0" /></a> <div align="justify">Coral, common name for members of a large class of marine invertebrates characterized by a protective calcium carbonate or horny skeleton. This protective skeleton is also called coral. Corals are divided into two subclasses, based on differences in their radial symmetry (symmetry around a central axis). One subclass consists of colonial, eight-tentacled animals, each with an internal skeleton. Among them are whip corals, gorgonians, and the red coral used in making jewelry. Members of the other subclass commonly have six tentacles, or multiples of six, but other patterns are also observed. They include the stony, or true, corals. Another class of the same phylum also contains forms known as coral that are not considered here.<br /><br /><strong>STRUCTURE</strong><br />True corals secrete calcium carbonate from the bottom half of the stalk of the individual animal, or polyp, forming skeletal cups to which the polyps are anchored and into which they withdraw for protection. In the flattened oral disc at the top of the stalk is an opening, edged with feathery tentacles and cilia, that is both mouth and anus. At night the tentacles extend from the cup, seize animal plankton that wash against them, and carry the food to the mouth. Stinging cells, or nematocysts, on the tentacles can also paralyze prey.<br /><br /><strong>COLONIES</strong><br />Some scleractinians exist as solitary polyps, but the majority are colonial. Colonial polyps average from 1 to 3 mm (0.04 to 0.12 in) in diameter. They are connected laterally by tubes that are an extension of the polyps' gastrovascular cavities, and the colony grows by asexual budding from the base or the oral disc of the polyps. Living polyps build on the deposits of their predecessors; the wide range of branched or massive forms that result depends on the species involved.<br /><br />Colonial corals can grow in deep water, but reef-building corals are found only in warm, shallow seas. They live no deeper than light can penetrate because the symbiotic <a href="http://kidsresearchexpress.blogspot.com/2008/08/algae.html">algae</a> called zooxanthellae that live in their tissues require light for photosynthesis, and the corals cannot exist without the algae. Carbon is passed by the algae to the coral, increasing its energy, and the food caught by the coral may supply nitrogen and phosphorus for both organisms. The dependence of the corals on the algae probably varies according to species and locality. Scleractinian corals are the main contributors to a reef, but other organisms also add to it, such as hydrozoan corals, calcareous algae, mollusks, and sponges. See <a href="http://kidsresearchexpress-3.blogspot.com/2009/04/coral-reef.html">Coral Reef</a>.<br /><br /><em>Scientific classification: Corals belong to the class Anthozoa in the phylum Cnidaria. Corals with eight tentacles make up the subclass Ostocorallia or Alcyonaria. Corals that commonly have six tentacles or multiples of six belong to the subclass Zoantharia (or Hexacorallia). Stony, or true, corals belong to the order Scleractinia (or Madreporaria). </em></div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-15069767588722879472008-10-18T22:08:00.000-07:002008-10-18T22:10:48.475-07:00Silkworm<div align="justify"></div><br /><div align="justify">Silkworm, common name for the silk-producing larvae of any of several species of moths. Silkworms possess a pair of specially modified salivary glands called silk glands, or sericteries, which are used in the production of cocoons. The silk glands secrete a clear, viscous fluid that is forced through openings, called spinnerets, on the mouthparts of the larva; the fluid hardens as it comes into contact with air. The diameter of the spinneret determines the thickness of the silk thread produced.<br /><br />The best-known silkworm is the larvae of the common, domesticated silkworm moth. This moth, native to China, was introduced into Europe and western Asia in the 6th century ad and into North America in the 18th century. The moth has been cultivated for many centuries and is no longer known in the wild state. Breeders have produced many varieties of the moth, the most important of which produce three broods of young annually.<br /><br />A typical adult silkworm moth is yellow or yellowish-white, with a thick, hairy body, and has a wingspread of about 3.8 cm (about 1.5 in). The adult has rudimentary mouthparts and does not eat during the short period of its mature existence; the female dies almost immediately after depositing the eggs, and the male lives only a short time thereafter. The female deposits 300 to 400 bluish eggs at a time; the eggs are fastened to a flat surface by a gummy substance secreted by the female. The larvae, which hatch in about ten days, are about 0.6 cm (about 0.25 in) long. The larvae feed on leaves of white mulberry, Osage orange, or lettuce. Silkworm caterpillars (see <strong>Caterpillar</strong>) that are fed mulberry leaves produce the finest quality silk. Mature larvae are about 7.5 cm (about 3 in) long and yellowish-gray or dark gray in color.<br /><br />About six weeks after hatching, the common silkworm stops eating and spins its cocoon. The length of the individual fiber composing the cocoon varies from 300 to 900 m (1000 to 3000 ft). The silkworm pupates for about two weeks; if allowed to complete its pupation period, it emerges as an adult moth. Tearing during emergence damages the silken cocoon beyond commercial use. Therefore, in the commercial production of silk, only enough adult moths are allowed to emerge to ensure continuation of the species. Most of the silkworms are killed by heat, either by immersion in boiling water or by drying in ovens.<br /><br />Other moths known as silkworm moths include the giant silkworm moths. The larvae of these large moths also spin silken cocoons, but they are less widely used for commercial silk production.<br /><br /><em>Scientific classification: Silkworms belong to the order Lepidoptera. The domesticated silkworm moth makes up the family Bombycidae and is classified as Bombyx mori. The giant silkworm moths make up the family Saturniidae. </em></div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-7261107655521914462008-09-21T05:17:00.000-07:002008-09-23T02:53:41.492-07:00Urinary System of the Animals<div align="justify"><span style="color:#ffffff;">.</span><br />All vertebrates dispose of excess water and other wastes by means of kidneys. The kidneys of fish and amphibians are comparatively simple, while those of mammals are the most complex. Fish and amphibians absorb a great deal of water and, as a result, must excrete large quantities of urine. In contrast, the urinary systems of birds and reptiles are designed to conserve water; these animals produce urine that is solid or semisolid. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-57214325989158673462008-09-21T05:12:00.000-07:002008-09-21T05:15:54.945-07:00Reproductive System of Animals<div align="justify"><span style="color:#ffffff;">.</span><br />In many invertebrate species individual animals bear both testes and ovaries (see <strong>Hermaphroditism</strong>). In some invertebrates, and in most vertebrates, individuals bear either testes or ovaries, but not both sets of organs. In invertebrates, a single animal may have as many as 26 pairs of gonads; in vertebrates, the usual number is 2. Cyclostomes and most birds are unusual among vertebrates in possessing only a single gonad; owls, pigeons, hawks, and parrots are unusual among birds in having two gonads. The size of gonads increases at sexual maturity because of the great number of germ cells produced at that time; many germ cells are also produced during breeding seasons so that many animals have a seasonal increase in size of the gonads. During the breeding season of fish, the ovaries increase in size until they constitute about one-quarter to one-third of the total body weight.<br /><br />The testes and ovaries of mature animals differ greatly in structure. The testes are composed of delicate convoluted tubules, known as seminiferous tubules, in which the primitive germ cells mature into spermatozoa. The testes of mammals are generally oval bodies, enclosed by a capsule of tough connective tissue. Projections from this tough capsule into the testis divide the testis into several compartments, each of which is filled with hundreds of seminiferous tubules. The mature spermatozoa are discharged through a number of ducts, called the efferent ducts, which communicate with the epididymis, a thick-walled, coiled duct in which the sperm are stored.<br /><br />In all vertebrates below marsupials on the zoological scale, and in elephants, sea cows, and whales, the testis remains within the body cavity during the lifetime of the animals. In many mammals, such as rodents, bats, and members of the camel family, the testis remains within the body cavity during periods of quiescence, but moves into an external pocket of skin and muscle, known as the scrotum, during the breeding season. In marsupials, and in most higher mammals, including the human male, the testes are always enclosed in an external scrotum. During fetal life, the testes move through the muscles composing the posterior, ventral portion of the trunk and carry with them the portion of the peritoneum and skin surrounding these muscles. The channel in the muscles through which the testis moves is known as the inguinal canal; it usually closes after birth, but sometimes remains open and is then often the site of herniation (see <strong>Hernia</strong>). The portion of the peritoneum that the testis carries with it forms a double wall of membrane between the scrotum and testis and is known as the tunica vaginalis. Occasionally, the testes in the human male do not descend into the scrotal sac; this condition of nondescent, which is known as cryptorchidism, may result in sterility if not corrected by surgery or the administration of hormones. Retention of the testes within the body cavity subjects the germ cells to temperatures that are too high for their normal development; the descent of the testes into the scrotum in higher animals keeps the testes at optimum temperatures. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-64880016725492186772008-09-21T05:06:00.000-07:002008-09-21T05:11:24.640-07:00Respiratory Systems in Other Animals<div align="justify"><span style="color:#ffffff;">.</span></div><div align="justify">The need to take in oxygen and expel carbon dioxide is almost universal among organisms. The movement of these gases between an organism and its environment, called gas exchange, is accomplished in a variety of ways by different organisms. In one-celled aquatic organisms, such as protozoans, and in seaweeds, sponges, jellyfish, and other aquatic organisms that are only a few cell layers thick, oxygen and carbon dioxide diffuse directly between the water and cells. Diffusion works for these simple organisms because all cells of the organism are within a few millimeters of an oxygen source.<br /><br />Animals with many cell layers cannot rely on diffusion because cells several layers deep in the body would die before oxygen reached them. As a result, for gas exchange, more-complex animals require special respiratory organs, such as gills or lungs, in combination with circulatory structures, such as blood, blood vessels, and a heart. The earliest development of these gas exchange structures is seen in <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/nematoda.html">roundworms</a>, microscopic invertebrates abundant in water and moist soil. In roundworms, oxygen diffuses through the skin into a fluid that fills an internal cavity. As the worm moves, the fluid sloshes around in the cavity, bringing oxygen into contact with the digestive system, reproductive organs, and other structures in the cavity. This primitive circulatory system is called an open circulatory system because the fluid is not contained within vessels. In clams an open circulatory system is combined with a heart that pumps fluid around the internal cavity. Clams also use gills, thin-walled filaments that are extensions of the body surface. Gills provide a more extensive surface area for gas exchange than the body surface alone, enabling clams and larger organisms to obtain the amount of oxygen they need. Fish have gills, a heart, and a closed circulatory system, one in which blood is transported in vessels by the pumping action of the heart.<br /><br />Relatively simple land-dwelling organisms, including some plants, fungi, and animals such as <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/platyhelminthes.html">flatworms</a>, accomplish gas exchange by diffusion. More-complex organisms, however, rely on specialized respiratory structures. Instead of gills, whose delicate filaments collapse unless supported by water, land animals use lungs. Located inside the body, lungs are formed by the infolding of membranes. The folds form a single balloon-like sac, as in amphibians; they may be arranged in stacks, as in the book lungs of spiders; or they are composed of millions of tiny air sacs, such as the lungs of most mammals. In virtually all vertebrates, a heart and a closed circulatory system work with the lungs to deliver oxygen and to remove carbon dioxide from cells.<br /><br /><strong>Insects</strong> have a unique respiratory system made up of small tubes called tracheae. The tracheae connect all parts of the body to small openings on the surface of the insect. Oxygen and carbon dioxide are transported through the tracheae, and from the tracheae to the blood of the insect by diffusion. The blood of most insects is contained in an open circulatory system and is moved around the internal organs by a heart.<br /><br />The respiratory system of <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/bird.html">birds</a>, adapted for flight, is very different from that of land-bound animals. The lungs have two openings, one for taking in oxygen-filled air; the other for expelling carbon dioxide-laden air. Rather than ending up in alveoli, the air loops through the lungs so that the oxygen flow through the lungs is continuous. This design enables birds to obtain the amount of oxygen they need to power the extremely high energy demands of flight. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-57606399115957654852008-09-21T04:55:00.000-07:002008-09-21T05:05:49.312-07:00The Vertebrate Nervous System<div align="justify"><span style="color:#ffffff;">.</span><br />Vertebrate Brains<br /><a href="http://1.bp.blogspot.com/_vZUSeG-88pw/SNY38M8UqdI/AAAAAAAABzU/QFFA9JaGe5g/s1600-h/Vertebrate+Brains.JPG"><img id="BLOGGER_PHOTO_ID_5248443923152808402" style="FLOAT: left; MARGIN: 0px 10px 10px 0px; CURSOR: hand" alt="" src="http://1.bp.blogspot.com/_vZUSeG-88pw/SNY38M8UqdI/AAAAAAAABzU/QFFA9JaGe5g/s400/Vertebrate+Brains.JPG" border="0" /></a><em>Although all vertebrate brains share the same basic three-part structure, the development of their constituent parts varies across the evolutionary scale. In fish, the cerebrum is dwarfed by the rest of the brain and serves mostly to process input from the senses. In reptiles and amphibians, the cerebrum is proportionally larger and begins to connect and form conclusions about this input. Birds have well-developed optic lobes, making the cerebrum even larger. Among mammals, the cerebrum dominates the brain. It is most developed among primates, in whom cognitive ability is the highest.<br /></em><br />Vertebrate animals have a bony spine and skull in which the central part of the nervous system is housed; the peripheral part extends throughout the remainder of the body. That part of the nervous system located in the skull is referred to as the brain; that found in the spine is called the spinal cord. The brain and the spinal cord are continuous through an opening in the base of the skull; both are also in contact with other parts of the body through the nerves. The distinction made between the central nervous system and the peripheral nervous system is based on the different locations of the two intimately related parts of a single system. Some of the processes of the cell bodies conduct sense impressions and others conduct muscle responses, called reflexes, such as those caused by pain (see <strong>Reflex</strong>).<br /><br />In the skin are cells of several types called receptors; each is especially sensitive to particular stimuli. Free nerve endings are sensitive to pain and are directly activated. The neurons so activated send impulses into the central nervous system and have junctions with other cells that have axons extending back into the periphery. Impulses are carried from processes of these cells to motor endings within the muscles. These neuromuscular endings excite the muscles, resulting in muscular contraction and appropriate movement. The pathway taken by the nerve impulse in mediating this simple response is in the form of a two-neuron arc that begins and ends in the periphery. Many of the actions of the nervous system can be explained on the basis of such reflex arcs, which are chains of interconnected nerve cells, stimulated at one end and capable of bringing about movement or glandular secretion at the other. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-71914992567523325272008-09-21T04:49:00.000-07:002008-09-21T04:54:01.986-07:00Digestive Systems of Animals<div align="justify"><span style="color:#ffffff;">.</span><br />The simplest invertebrates (animals without backbones) do not have specialized digestive organs. Single-celled organisms, such as <strong>amoebas</strong>, rely on intracellular digestion (digestion within the cell). Some many-celled organisms, such as the sponge, also use intracellular digestion. The sponge obtains the tiny organic particles that make up its diet from water passing through its body. Water enters through the sponge’s pores and leaves through an opening called the osculum. As water flows through the interior canals of the sponge, specialized cells that line these canals, called collar cells, catch and engulf organic matter. Inside the collar cells, sacs called vacuoles form around the food and enzymes digest it. The digested food then passes to other cells in the sponge’s body.<br /><br />Intracellular digestion meets the needs of simple animals, but more complex organisms require systems that are more specialized. Animals such as <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/jellyfish.html">jellyfish</a> and nonparasitic <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/platyhelminthes.html">flatworms</a> combine the intracellular process with some specialized digestive organs. These animals have a definite mouth and a saclike cavity, which is lined with digestive cells that secrete enzymes. Digestion begins when the enzymes break down food inside the cavity in an extracellular (outside the cell) process. Cells then engulf the partly digested food, and an intracellular process similar to that of sponges completes digestion. Wastes are excreted through the mouth.<br /><br />Most of the more complex invertebrates and all vertebrates (animals with a backbone) digest food entirely through extracellular processes. Food moves in one direction, from mouth to anus, through the series of organs that make up the alimentary canal. Specialization of various parts of the alimentary canal improves the body’s ability to break down food and absorb various kinds of nutrients. The mouth of many animals contains teeth or other structures to break up large lumps of food. Behind the mouth, the pharynx and esophagus swallow the food and move it to the stomach. The stomach temporarily stores the food, mixes it with digestive juices, and carries out some digestion.<br /><br />Digestion is completed in the intestine. The liver and pancreas pour their digestive juices into the anterior (front) end of this organ. After the anterior intestine absorbs the usable products of digestion, the walls of the posterior (rear) intestine absorb leftover water. In vertebrates the anterior intestine is called the small intestine; the posterior intestine is the large intestine. <strong>Feces</strong>, composed of unabsorbed and indigestible food residues, form in the posterior intestine, where they are stored until they are excreted through the anus.<br /><br />Within this basic plan, the specific components of the digestive system vary enormously from one animal to another. For example, a fish’s pharynx contains gill slits for breathing but has no digestive function. An earthworm’s stomach consists of two organs: a crop, in which food is stored, and a muscular <strong>gizzard</strong>, which carries out mechanical digestion by grinding food against particles of sand. The stomachs of <strong>ruminant</strong> mammals, such as cattle and deer, consist of three or four compartments, each performing a specific function. Amphibians, reptiles, and birds have an organ called a <strong>cloaca</strong>, which serves as an exit for both digestive wastes and sex cells. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-88854166359405018682008-09-21T04:45:00.000-07:002008-09-21T04:48:22.593-07:00Circulatory Systems in Non-Humans<div align="justify"><span style="color:#ffffff;">.</span><br />One-celled organisms and many simple multicelled animals, such as sponges, jellyfishes, sea anemones, flatworms, and roundworms, do not have a circulatory system. All of their cells are able to absorb nutrients, exchange gases, and expel wastes through direct contact with either the outside or with a central cavity that serves as a digestive tract.<br /><br />More complex invertebrates have a wide range of circulatory system designs. These invertebrate circulatory systems are classified as either open or closed. Open systems—found in starfishes, clams, oysters, snails, crabs, insects, spiders, and centipedes—lack capillaries, and the blood bathes the tissues directly. In closed systems, the blood is confined to a system of blood vessels. Invertebrates with closed systems include segmented worms, squids, and octopuses.<br /><br />All vertebrate animals have closed circulatory systems. These systems are classified by the number of chambers in the heart, which determines the basic configuration of blood flow. Fish have two-chambered hearts with one atrium and one ventricle. Blood pumped from the ventricle travels through arteries to the gills, where it diverges into capillaries and exchanges gases. Leaving the gills, the capillaries reconvene into blood vessels that carry the oxygenated blood to the rest of the body, where the vessels again diverge into capillaries before reconvening into veins that return to the heart. In this way, the blood passes through first the respiratory organs (the gills) and then the systemic circulation between each pass through the heart.<br /><br />Frogs and amphibians have three-chambered hearts, with two atriums and one ventricle. Blood pumped from the ventricle enters a forked artery. One fork, the pulmonary circulation, leads to the lung. The other fork, the systemic circulation, leads to the rest of the body. Blood returning from the pulmonary circulation enters the left atrium, while blood from the systemic circulation enters the right atrium. Although there is some mixing of oxygenated and deoxygenated blood in the ventricle, a ridge within the ventricle assures that most of the oxygenated blood is diverted to the systemic circulation and most of the deoxygenated blood goes to the pulmonary circulation. In reptiles, this ridge is more developed, forming a partial wall. In crocodiles, the wall is complete, forming a four-chambered heart like that found in mammals and birds. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-83092738109019562312008-09-16T07:14:00.001-07:002008-10-18T22:22:11.582-07:00Aquaculture<div align="justify"></div><br /><div align="justify">Aquaculture, farming of aquatic organisms in fresh, brackish or salt water. A wide variety of aquatic organisms are produced through aquaculture, including <a href="http://kidsresearchexpress-8.blogspot.com/2008/09/fish.html">fishes</a>, <strong>crustaceans</strong>, <strong>mollusks</strong>, <a href="http://kidsresearchexpress.blogspot.com/2008/08/algae.html">algae</a>, and aquatic plants. Unlike capture <strong>fisheries</strong>, aquaculture requires deliberate human intervention in the organisms' productivity and results in yields that exceed those from the natural environment alone. Stocking water with seed (juvenile organisms), fertilizing the water, feeding the organisms, and maintaining water quality are common examples of such intervention.<br /><br />Most aquacultural crops are destined for human consumption. However, aquaculture also produces bait fishes, ornamental or aquarium fishes, aquatic animals used to augment natural populations for capture and sport fisheries (see <strong>Fishing</strong>), algae used for chemical extraction, and <strong>pearl oysters</strong> and <strong>mussels</strong>, among others.<br /><br />Aquaculture is considered an agricultural activity, despite the many differences between aquaculture and terrestrial agriculture. Aquaculture mainly produces <a href="http://kidsresearchexpress-6.blogspot.com/2008/08/protein.html">protein</a> crops, while starchy staple crops are the primary products of terrestrial agriculture. In addition, terrestrial animal waste can be disposed of off-site, whereas in aquaculture such waste accumulates in the culture environment. Consequently, aquaculturists must carefully manage their production units to ensure that water quality does not deteriorate and become stressful to the culture organisms. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-38358447918953745782008-09-16T07:13:00.007-07:002009-10-15T05:08:46.558-07:00Ruminant<div align="justify">Ruminant, even-toed animal that regurgitates and masticates its food after swallowing. The majority of ruminants have four nipples; they usually have sweat glands only on the muzzle and between the toes. Most species bear horns that may be permanent or may be shed periodically. The division includes three subdivisions: Tragulina, containing the chevrotains and characterized by a stomach with three chambers; Tylopoda, consisting of the camel, dromedary, llama, alpaca, guanaco, and vicuña, and characterized by a stomach with three distinct chambers; and Pecora, containing all sheep, goats, antelope, deer, gazelles, giraffes, and domestic cattle, and characterized by the presence of a distinct four-chambered stomach. Pecoran animals are known as true ruminants. Between the esophagus and the intestine, the stomach chambers of a true ruminant are the rumen, the reticulum, the omasum, and the abomasum, or rennet bag.<br /><br /><em>Scientific classification: Ruminants make up the suborder Ruminantia of the order Artiodactyla. </em></div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-63364990411298142492008-09-16T07:13:00.005-07:002009-10-15T05:13:07.020-07:00Amoeba<div align="justify">Amoeba, any of a group of unicellular organisms characterized by their locomotive method of extending cytoplasm outward to form pseudopodia (false feet). The amoeboid group includes hundreds of different organisms, ranging in size from about .25 to 2.5 mm (about 0.0098 to 0.098 in). Amoebas are considered the most primitive animals and are classified in the kingdom Protista. All amoeboid organisms have thin cell membranes, a semirigid layer of ectoplasm, a granular, jellylike endoplasm, and an oval nucleus. Some species live on aquatic plants and some in moist ground; others are parasitic in animals.<br /><br />Amoebas also use pseudopodia for feeding. Chemical stimuli from smaller organisms, the amoeba's food, induce the formation of pseudopodia, pairs of which envelop the organism, at the same time forming a cavity, or vacuole. A digestive enzyme secreted into the cavity breaks down this food into soluble chemical substances that then diffuse from the cavity into the cytoplasm. Undigested food and wastes are excreted through the ectoplasm, which also absorbs oxygen from the surrounding water and eliminates carbon dioxide, a by-product of metabolism, in a form of respiration. After a period of growth, the amoeba reproduces by splitting into two equal parts.<br /><br />At least six forms of amoeba are parasitic in humans. Most important of these is Entamoeba histolytica, which causes amebiasis and dysentery. The diseases often occur in epidemics when raw sewage contaminates water supplies or when soil is fertilized with untreated human wastes. </div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0tag:blogger.com,1999:blog-7556844179720856351.post-46238838433232236492008-09-10T06:42:00.000-07:002008-09-10T06:43:18.951-07:00Sipuncula<div align="justify"><span style="color:#ffffff;"> .<br /></span>Peanut Worm, common name for small, unsegmented marine worms having bulb-shaped bodies and bearing crowns of tentacles on long, slender, processes, called introverts, that can turn inside out. Peanut worms are common but inconspicuous, frequently nestling among shells; they can burrow, but they move slowly. The main part of the body contains a single cavity (the coelom) filled with fluid under pressure from the body musculature. When the introvert turns inside out, the tentacles at its tip are used for feeding on small particles of organic matter. The placement of peanut worms in the animal kingdom is uncertain, but they are probably close to the annelid worms. Little structural diversity exists within the group; about 250 species have been described.<br /><br /><em>Scientific classification: Peanut worms make up the phylum Sipuncula. </em></div>piayachoohttp://www.blogger.com/profile/13044272628617391460noreply@blogger.com0