When did Pterodactyls live?



Pterodactyls (or pterosaurs) lived between 150 million and 70 million years ago. These extraordinary reptiles were able to fly. Some had a wing-span of over 25 feet, making them by far the largest flying animals known to man. Their skulls were often longer than four feet.



     Unlike the birds, their descendants, pterodactyls must have been unable to perch upright. They probably hung upside down like bats when sleeping or at rest.



     Since most remains of pterodactyls have been discovered among marine sediments, it seems likely that these flying dinosaurs found their food in the sea, like seagulls, by diving for fish.



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What do birds of prey eat?


Birds of prey are those that feed wholly or mainly on meat taken by hunting. They catch other birds, and small animals, for their food.



    There are two chief families, the hawks and the falcons. The hawks include eagles, such as the bald eagle (symbol of the United States) and the golden eagle. The falcons are smaller but share the same general characteristics-hooked beaks, keen vision and outstanding powers of flight. Owls, also. Feed on flesh.



    Besides being fast flyers, many birds of prey are expert at gliding and hovering. Their principal strategy of attack is the “stoop”, when from a great height they sight their prey, close their wings and swoop upon the victim. This manoeuvre calls for a combination of speed and last second breaking unique to this type of bird.



    In advanced countries birds of prey have suffered severely from the effects of poisonous agriculture sprays which have polluted their food sources. This has threatened their survival. But the danger has now been recognized, and in many areas their numbers are slowly recovering.



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Where does a bee keep its sting?


A bee keeps its sting at the end of its abdomen. At the tip of a bee’s abdomen is a shaft where is stinging thorn is to be found. It can sting several times, but once it leaves the thorn in its victim’s flesh it will not be able to sting again.



    It is not true to say that a bee will automatically die once it loses its thorn. Only female bees can sting. Male bees, or drones, lack this means of protecting themselves.



     There is a species of which even the female cannot sting. But these bees which live mainly in Africa and South America are not defenseless. If disturbed, they will fly at he intruder in great numbers, crawl into his eyes, ears and hair and smear him with a sticky substance, causing him to retreat in great discomfort.



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Why do most fish have scales?


Fish have scales as a protective coating for the skin. In fact, not all fish have them. But we usually think of a fish as a cold-blooded, aquatic animal that swims by means of fins, breathes by means of gills, and is covered with scales. Scales may be of four different kinds-placoid, ganoid, cycloid and ctenoid.



Placoid scales are long, spiny and tooth like, and are made of enamel and dentine. These are found on fishes which have a back-bone made of gristle, such as sharks and rays.



   Ganoid scales are rather like placoid scales but are mainly bony and covered with a kind of enamel called ganoin. These thick scales are found especially in garfish.



    Cycloid scales are thin, large round or oval scales arranged in an overlapping pattern. They are found in carps and similar fishes.



Ctenoid scales are similar to the cycloid ones, but have spines or comb like teeth along their free edges. These are found in the higher bony fishes, such as perches and sunfishes.



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What is a greenshank?


A greenshank is a little bird with a long beak and olive-green legs-a member of a group of birds known as sandpipers.



       The greenshank breeds in Scotland, Norway, Sweden and Finland. It builds its nest on the ground, being content usually to settle in a small hollow, lined with heather or dry grass. The eggs are pale buff or stone colour, blotched with purplish-grey and spotted with dark brown.



       Worms, insects and tiny fish provide the bird’s food. In winter the greenshank migrates, some-times as far south as Australia or South Africa.



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Where would you find live prehistoric fish?


Numerous fossil remains have been found of coelacanth fish which died over 70 million years ago. In fact the coelacanth is said to have first appeared some 350 million years ago.



      But to the amazement of experts the first living coelacanth was found in 1938 off the coast of South Africa. In 1952 a second one was caught on a line by a fisherman from the Comoro Islands, between Mozambique and Madagascar. Since then many more coelacanths have been taken around the Comoros.



      Modern coelacanths are bigger than most of the fossil forms. They average about five feet in length and can weigh more than 100 pounds.



      Usually they live among reefs, from which they will dart out on their prey. they are strong and powerful flesh eaters. The heart of a coelacanth is an S-shaped tube and is probably the most primitive of its kind in existence today.



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Why do bats make high-pitched sounds?


Bats use high-pitched sounds to find their way about. They are nocturnal animals. That is they move about by night. So they have developed their hearing to such an extent that they can find their way by a method known as echolocation.



     The blind-flying abilities of bats were first studied by LazzaroSpallanzani (1729-1799). He surgically removed the eyeballs from several bats to prove that they did not need to see to fly.



    In the 20th century, biologists, using electronic instruments, have carried out experiments with bats. They have discovered that bats find out where to go by emitting high-frequency sounds and receiving the echoes as they bounce off objects. Most of the sounds have too high a frequency to be heard by the human ear.



    Bats commonly fly together in groups, but apparently they are not confused by he sounds and echoes produced by each other. When hunting in woods and in the rain they are able to discriminate between the faint echoes bouncing off the ground, tree-trunks, branches, twigs and raindrops.



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When were breakfast cereals first used?


Cereals, of course, in the general sense, including wheat, rice, maize (known as corn in Canada and the United States), rye, oats and barley were among the earliest plants grown by man. But packaged or processed cereals are a modern development.



      Breakfast cereals owe their origin to the vegetarians of the last century and health fanatics who believed they could save souls by preaching the virtues of a non-meat diet.



Granula, which was the beginning of Grape-Nuts, was launched in 1863 by a man called James C. Jackson, of Danville, New York. Henry D. Perkey brought out Shredded Wheat in 1893 and Puffed Wheat was developed by Alexander Anderson in 1902.



    The religious sect, the Seventh Day Adventists, made Battle Creek, Michigan, the cereal headquarters of the world when the sect formed the Western Health Reform Institute at Battle Creek in 1866, later called the Battle Creek Sanatorium. John Harvey Kellogg, who was a doctor and a writer, took over control of the Santorium in 1876 and his advocacy of cereals helped to develop what was to become a vast new food industry. His brother, W.K. Kellogg, started a cereal producing company in 1906.



    C.W. Post was another cereal pioneer and his Postum Cereal Company formed in 1897 later developed into General Foods Corporation.



    The basic idea behind packaged cereals has remained largely unchanged.



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Who uses a Cardiac pacemaker?


Cardiac pacemakers are used by sufferers from “heart-block”. They do the work normally performed by the body’s natural pacemaker in controlling the rate and rhythm of the heart beats. This natural pacemaker is a small collection of specialized nervous tissue situated at the base of the heart. It forms the starting point for the impulses that initiate the heartbeats.



    “Heart-block” is a serious condition in which the conducting mechanism between the cavities of the heart (atrium and ventricle) is impaired or destroyed. When this happens, the atrium and ventricle beat at different rates independently of each other because the impulse from the pacemaker is not reaching all parts of the heart. Fainting, convulsive attacks or complete stoppage of the heart may follow, but the condition can be overcome by the use of an artificial pacemaker.



      This acts as a battery to stimulate the heart, allowing it to beat regularly at normal speed, about 70-80 impulses a minute. The pacemaker is either fixed to the outside of the chest or implanted in the armpit and connected to an electrode tube, which is passed through the main vein in the neck into the heart.



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What is muscle?


Muscles are the body tissue which, because it has the power of contraction, enables the higher animals to move their bodies. Muscles are divided into two great groups, voluntary and involuntary, the former being controlled by the will, while the latter act independently



     Most voluntary muscles are attached to the skeleton and range in size and shape to suit the particular jobs they perform. They can get into action within a few hundredths of a second, exert an enormous pull on the bone to which they are attached and, if necessary, support 1,000 times their own weight. Involuntary muscles include heart muscle and the muscles of the digestive system, and the fibers of which they are composed are very much smaller than those of voluntary muscle.



    Because of its exceptionally rich blood supply, muscle is the most infection-free of the body’s basic tissues. If it is over-taxed it tires and will stop contracting altogether, but if used normally will give little trouble.



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Why do we sleep?


Some scientists consider that sleep is an instinct, a basic need for the body and mind to relax and to escape from the responses needed while awake. We become tired in body and mind if we do not sleep, and scientists have proved that when we do sleep the electrical activity of the brain slows down, although it may be stimulated when we dream.



     One chemical theory is that a substance needed to maintain the waking state becomes exhausted and may be replenished in sleep. A contrary suggestion is that some poisonous substances built up in wakefulness may be destroyed when we go to sleep.



   Other theories connect the need for increased wakefulness with the development of the more sophisticated areas of the brain. This could explain why new-born babies whose powers of reasoning have not yet developed, spend most of their lives asleep. It has been demonstrated that a particular formation, if severed, causes continues sleep.



     Although we are not sure why we sleep, there is no doubt that we need to do so and so do most other animals. The pattern of sleep and wakefulness is closely connected with our habits and senses. Animals which depend upon sight for food, shelter and defense, like man, are diurnal. That means they are for the most part active during the day and asleep at night.



    The amount of sleep needed by a person to remain in full health varies considerably with age, with different individuals, and even, perhaps, with race. Pre-school children generally need ten to twelve hours sleep schoolchildren nine to eleven hours and adults seven to nine hours. Adults seem to need progressively less sleep as they grow older, and exceptional cases are known of elderly people who have remained healthy on two to three hours a night. It has been said that the Japanese, children and adults, sleep less than Europeans, but that may be due to habit rather than to race.



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When were contact lenses invented?


The first contact lenses were made by A.E. Fick in 1887, but were not successful. During the early part of this century opticians tried to produce extremely thin shell-like lenses to fit closely over the eye. An impression was taken of the eye and a glass shell made which, with a suitable fluid under it, covered most of the eye. After 1938, plastic was used instead of glass, and in about 1950, smaller lenses were introduced which covered only the cornea and floated on a layer of tears. These lenses, only 7 to 11 mm in diameter and 0.1 to 1mm thick can usually be worn all day without being removed.



    Besides being invisible, contact lenses provide a much wider field of vision than spectacles. They are more practical for use in active sports because they are not easily lost or broken, and they can be tinted for use as sunglasses. But contact lenses are not effective in all cases of eye trouble. They are also expensive, and some people find difficulty in learning to wear them.



    As research continues, even smaller and more flexible lenses are being developed.



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