Catfish

Catfish comprise about 2,000 species of mostly freshwater fishes in the order Silurifrmes. Distributed worldwide, they are most diverse in South America. Catfish are distinguished by the presence of barbells, or whiskers; the lack of true scales; strong spines at the front of the dorsal and pectoral fins; and in most cases, an adipose fin on top of the body is usually partly to completely armored. Most catfish have small eyes, they rely on taste, smell, and hearing. The barbells and much of the skin are often covered with taste buds. Many catfish are inactive during the day, coming out to feed at night. Freshwater catfish usually spend mush of their time (and lay their eggs) in hollow logs, undercut banks, and other hiding places. One or both parents guard the eggs until they hatch. In Indonesian this fish is called "lele".

Many species of fresh water catfish are used for human food. North American catfish of the genus Ictalurus are important commercially and are popular with anglers. Catfish farming involves raising and marketing such species as the channel catfish, I. punctatus.

Some catfish are quite distinctive in appearance or behavior. A parasitic catfish, the candiru, Candellis cirrhosa, a minute South American catfish with strong, recurved spines, has been known to enter the urinary tract of persons wading in the water. The electric catfish Malapterurus electricus, native to Africa, can produce a charge of up to 350 volts, enough to stun a human. The predatory walking catfish, clarias batrachus, has lunglike organs that allow it to breathe air, enabling it to move over land from one body of water to another. A European catfish, the wells, Silurus glanis, is one of the largest freshwater fishes, reaching 4,5 m (15 ft) in length and 300 kg (660 lb) in weight.

Catfish are bottom dwelling fish marked by the presence around the mouth of sensitive tactile organs (barbells) that look like a cat's whiskers.

Caterpillar

A caterpillar is an elongate, wormlike larva of an insect, particularly of Butterfly and Moths. Typically long and slender, a caterpillar consists of three regions; head, thorax, and abdomen. The mandibles, or jaws, are effective in chewing plant matter. The thorax bears three pairs of short legs, and the abdomen usually bear a pair of fleshy prolegs on each of the third to sixth segments and on the tenth, or last, segment. Caterpillars of small moths rarely exceed 5 mm (0.2 in) in length; those of the largest may measure up to 155 mm (6 in). They are often brightly colored and patterned, and many have hairs of pines, which are sometimes poisonous.

Caterpillars are essentially the nutritive and growth stage of the insects life span. Ecologically, they are enormously important, transforming large amounts of plant matter into animal matter and wastes, as well as serving as food for other animals. Many caterpillars, however, are destructive to crops and shade trees.

Echolocation

Echolocation is the use of the echoes of sounds produced by certain animals to detect obstacles in their path and perhaps to locate food. The term echolocation was coined (1944) by Donald R. Griffin to describe this process. The list of echolocators includes may bats, porpoises, some whales, several species of birds and some shrews. Blind people and animals that live where the lighting is unpredictable also use a form of echolocator.

Sound used in echolocation may be produced in the voice box, the mouth, or some part of the head, and in all cases highly refined auditory systems detect returning echoes. For echolocation to work, each outgoing pulse of sound must be registered in the organism's brain, where it will be compared to its echo. Porpoises, birds, and some bats use loud orientation sounds, which pose a problem of self-deafening. The problem is resolved in bats by neutral and muscular modifications in their auditory system.

Echolocation is mistakenly associated with high-frequency sound, or ultrasound. In fact, the echolocations sounds of oil birds and cave shiftiest are quite audible to the human ear, as are those of some bats. Most bats use pulses of ultrasonic sound (inaudible to humans) because high-frequency sounds provide better resolution of targets than do lower-frequency sounds. Insectivorous bats use a wide array of echolocation strategies involving changes in loudness and frequency.

A bat judges the distance to its prey by reflecting sounds it has emitted. Echolocation is also used to navigate in dark caves or at night.

Bison

Bisons comprise two species of the genus Bison. One, commonly but incorrectly known as the buffalo, is the American bison. The other, the European species, is the wisent.

The bull of the American bisen, Bison, may weight more than 900 kg (about 2,000 lb) and stand more than 1.9 m (6 ft) high. The massive head and forequarters are covered with long hair, and the body slims down toward the hindquarter, which are covered with shorter hair. The female of the species is somewhat smaller. Both sexes have horns, but those of the male are more massive.

The bison was a principal resource of the Plains Indians, providing food, skims for shelter and boats, bones for tools and utensils, and "buffalo chips" (dung) for fuel. Few wild animals have undergone a more devastating encounter with humans. The grasslands from the Mississippi River to Rocky Mountains were home to 30 million bison when white settlers first arrived. These numbers were reduced to about 500 near the end of the last century, and then slowly increased to an estimated 35,000 to 50,000 on refuges and ranches today.

The European bison, or wisent, B. bonasus, may weigh up to 1,000 kg (2,200 lb) and stand more than 2 m (6 ft) high. It lack the shaggy coat of the American bison and has longer legs and a smaller head with longer horns. The wisent inhabits woodlands and feeds on grasses, ferns, leaves, and tree bark. At one time it ranged from western Europe to Siberia, but the destruction of forests led to its decline. On the verge of extinction in the early 1900s, the wisent is no longer endangered; captive breeding has been successfully used to increase the dwindling population.
The massive American bison is aggressive and easily angered. Before combat, a bull competes with other bulls in roaring.

Grouse

Grouse, order Galliformes, are popular game birds of the family Tetranidae and are related to the other gallinaceous birds including turkeys and quail. Like their relatives, grause are heavy-bodied, chicken like ground dwellers and have a short, heavy bill and short, rounded wings. They are medium sized, 30.5-88.9 cm (12-35 in) long. The feet and nostrils are covered with feathers. Grouse eat seeds, insects, bark, and buds.

The tetraonids, which include the Ptarmigans, have insulating double feathers and feathered feet; even the toes are feathered in the ptarmigans. So-called snowshoes, shed in summer, are characteristic of some species. Tetraonids also have erectile feathers-rusfts or pinnae-on the sides of the neck, and some have inflatable carvical pouches for producing the booming sounds characteristic of some species. They lay large clutches of eggs. Intestinal ceca harbor bacteria that function in the microbial decomposition of cellulose, prominent in their diet.

The sage grouse feeds primarily on sagebrush. Characteristic of all members of the grouse family are feather covered nostrils and legs. The elaborate courtship of the male the use of a collective display site called a lek.

Camel

The camel is a cud-chewing mammal of the family Camelidae, order Artiodactyla. It is distinguished from other camelids-the Alpaca, Guanaco, Llama, and Vicuna-by the one or two fal-filled humps on its back. The family arose in North America and, about 10 million years ago, began spreading to other continents. It became extinct in North America itself about 2 million year ago.

Two species of camel now exist; the one-humped dromedary, Camelus dromedarius, and the two-humped Bactrian, C. bactrianus. The dromedary was domesticated more than 5,000 years ago in the Middle East, serving as a means of transport and as a source of milk, meat, wool, hides, and dried manure for fuel. The more docile Bactrian of Central Asia was domesticated about 2,500 years ago.

Adult male dromedaries stand about 2 m (7 ft) at the shoulder and weigh up to 680 kg (1,500 lb). Bactrians are shorter because of shorter legs. The gray to brown coat is short and fine in drodaries, longer in Bactrians. Both species are well adapted to desert life and temperature extremes. Their two-toed feet have spreading, padded toes for walking on sand. When camels move quickly, both legs on the same side of the body advance together, producing a rolling gait.

Camels can obtain enough water from desert vegetation to survive for many months without another water supply. The animals can tolerate water losses equal to 25 percent of their body weight, and they excrete concentrated urine. Other internal modifications enable them to maintain a steady water level in the blood and to drink animals. By having fat localized in a hump, the body is able to lose heat more rapidly. When these fat reserves are called upon, the hump shrinks and tends to sag.

The dromediary, or one-humped camel can be trained to carry heavy loads on long journeys. Adapted to life in the desert, the camel has horny pads on the knees, thigh joints, and chest openings and nostrils for protection from sand and wind.

The Bactrian, or two-humped, camel has shorter legs than the dromedary and is nor able to move as swiftly at its fastest pace. A few wild bands still roam the Gobi.