Category Zoology

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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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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