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One of the most (1) ___ things in nature is the ability of certain creatures to find their way home, sometimes from great distances. Birds are not the (2) ___ ones who can do this. Bees, eels, and salmon are able to return to a (3) ___ place after long journeys, too.
Most migrations take place between (4) ___ places and regions where animals feed. For some animals, such as the lemming, the move is a one-way trip. Some scientists call this movement emigration, because these animals never return to their homes. For other animals, such as birds, the migration includes a (5) ___ trip home. Birds move in periodic migration, or at (6) ___ times during their lives, and often to the same place year after year.
Certain types of butterflies migrate, too, and find their way home over (7) ___ distances. In the tropics one can sometimes see great (8) ___ flights of butterflies all flying (9) ___ in one direction. They may go a thousand miles and more and then return again in another season.
Despite all the (10) ___ that have been made to explain how these creatures find their way home, we still have no (11) ___ explanation. Since many of the birds fly over great (12) ___ of water, we can’t explain it by saying they use (13) ___ to guide them. Just to say they have an “instinct” does not really explain the actual (14) ___. The reason they do it may be to obtain food or to reproduce under the right conditions. But the signals and (15) ___ they use on their flights are still a mystery to man.
14. Заполните пропуски подходящими по смыслу словами из предложенного списка.
Curious facts about animals
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HIPPOS
During a nightly grazing session, a hippo can eat up to 40 kg of grass and dead leaves. This (1) ___ to about 12 full sacks of food.
When a hippopotamus dies, other hippos (2) ___ the corpse and lick it. They may remain like this for a whole day, driving away any hungry crocodiles. They only (3) ___ the corpse when the crocodiles become too numerous to (4) ___.
ANTS AND FUNGUS FARMING
Leaf-cutter ants feed their larvae on fungus that they (5) ___ themselves in underground gardens. The ants depend on the fungus for food, and the fungus cannot (6) without the ants. When a new queen takes flight to (7) ___ another colony, she takes some of the fungus with her in a special mouth pouch.
FISHY CHLOROPHYLL
The eye retina of the deep see fish malecosteus niger (8) ___ chlorophyll. This is the only known instance of chlorophyll being found in an organism that is not plant or bacteria.
PREGNANT MALES
In sea horses it is the male that carries the babies. The female (9) ___ her eggs into his brood poach, where he fertilizes them. They (10) ___ there up to six weeks while he (11) ___ them till they reach independence.
SHARKS NEVER STOP
Sharks have to keep swimming to (12) ___. The great white shark must swim constantly at about 3,5 kmh to (13) ___ enough oxygen reaches its bloodstream. An immobile shark (or one dragged backward) drowns.
EATING WITH THEIR EYES
Frogs and toads never eat with their eyes open. When eating, they have to push back their eye balls in order to (14) ___ food into the stomach.
LOBSTERS LINE UP FOR EFFICIENCY
When spiny lobsters (15) ___, they do so by walking in lines of up to 65 along the seabed, each clinging with its claws to the rear of the one in front. Scientific experimentations with sea lobsters , weights and pulleys have shown that such an arrangement (16) ___ drag and allows a 25% improvement in speed through the water.
ACCELERATING FLEAS
As a flea jumps, its rate of acceleration is 20 times that of the space shuttle during launching. It (17) ___ a speed of 100m per sec within the first 500th of a second.
MAGNETIC MOLLUSK
The chiton, a species of marine shelled mollusk, (18) ___ magnetism to find its way home. The teeth on its tonguelike radulla contain magnetite, and (19) ___ the chiton to return to exactly the same place on its home rock after nighttime feeding.
RADIOACTIVE RESISTANT BACTERIA
The bacterium Deinococcus radiourans can (20) ___ at gamma radiation levels of up to 50 000 grays – thousands times greater than that needed to kill a human.
JOKES
Prayer: “Dear Lord, help me be the kind of person my dog thinks I am.”
– Do you know it takes three sheep to make a sweater?
– I didn’t even know they could knit.
I crossed a carrier pigeon with a woodpecker so that it would not only carry messages but also knock on the door when it arrived.
Two pigeons were flying over a car dealer’s and one said, “Why don’t we put a deposit on that Mercedes?”
The farmer’s new scarecrow is so intimidating that not only have the crows stopped stealing his corn, they are even bringing back the stuff they stole last year.
I sent my dog to an obedience school. He still bites me, but at least he looks very embarrassed.
1. Образуйте соответствующее однокоренное слово.