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Why Do rabbits Have Large Ears?
Rabbits are timid animals with many enemies and rely on their large ears to warn them of the sound of approaching(接近的) danger.Their ears act like old-fashioned(旧式的) ear-trumpets. The large area catches a great many sound waves and channels(引导) them into the rabbit?蒺s inner ear.
Wild rabbits spend some of the day underground, usually coming out to feed between dusk and dawn. They are continually on the alert(警惕着)，their long ears twitching(抽动) and moving round to pick up the faintest sound from an enemy. They also have a keen sense of smell.
Long back legs give rabbits speed. But they are virtually(实际上) defenceless and , in fact, often seem to be hypnotized（恍惚) by approaching predators(捕食动物的动物). When this happens, they crouch(蹲伏) squealing（尖叫) and make no attempt to run away.Only their extraordiary fertility(繁殖力) has enabled them to survive the onslaughts of foxes, badgers, wild cats, martens, stoats, weasels, polecats, dogs, man and disease.
Why Do Some Elephants Have Very Large Ears?
African elephants have larger ears than Indian, or Asiatic, elephants because they live in hotter conditions and are bigger and even aggressive and active. The huge ears of the African elephant, sometimes three and a half feet wide, enable it to hear more acutely(敏锐). When the animal charges its fans out its ears, augmenting(使扩大) its terrible appearance and striking fear into the heart of any enemy.
The ears also present a large surface for losing body-heat. African elephants, who are at a disadvantage(不利) in the heat because of their large size, wave their ears to keep cool and to chase away flies. The African elephant is the biggest and noblest of land animals, reaching a height of 11 feet and a weight of nearly six tons.
The Asiatic elephant is smaller. It inhabits(栖居) the forests of south-east Asia from India to Sri Lanka and Kalimantan. It does not like heat and seeks the deep shade of the forest.
When Does a Chameleon Change Colour?
A chameleon(变色龙) will change colour when it senses danger.The remarkable member of the lizard family(蜥蜴类动物) can change colour to match its background(变出同周围事物同样的颜色) or , at least, to become almost unrecognizable.
The ranges of colours and patterns of the various species(种类) differ widely, but most chameleons can become yellow or cream, green or dark brown. They can also adapt(适应) spots either dark or light depending on the colour of the ground.
Apart from its response(反应) to danger, the chameleon will change colour according to the light and temperature. This mechanism(技能) is controlled from the nervous system and involves(包括) the dispersion(消散) or concentration of colour pigments(色素) in the creature?蒺s skin.
When Does Sharks Attack Humans?
Some sharks(鲨鱼) may attack human beings if attracted by underwater noises, the presence of a large number of bathers(游泳者), or the glint(闪耀，反射) of jewellery or some other article. But probably the greatest provocation(刺激) to a shark is the presence of blood, for example from a spread fish or live bait(饵).
Sharks are most likely to attack during the daytime, the areas of greatest danger being those where the sea temperature is between 16° and 21° Centigrade. Most attacts seem to occur(发生) about 200 to 300 feet from the shore where the water is shallow— or no more than two or three feet in depth.
Among the kinds of sharks known to attack human beings are tiger and the blue and grey nurse sharks. The most feared of the shark family is the great white shark, a powerful and aggressive（攻击性强的） creature.
Rabbits are timid animals with many enemies and rely on their large ears to warn them of the sound of approaching(接近的) danger.Their ears act like old-fashioned(旧式的) ear-trumpets. The large area catches a great many sound waves and channels(引导) them into the rabbit?蒺s inner ear.
Wild rabbits spend some of the day underground, usually coming out to feed between dusk and dawn. They are continually on the alert(警惕着)，their long ears twitching(抽动) and moving round to pick up the faintest sound from an enemy. They also have a keen sense of smell.
Long back legs give rabbits speed. But they are virtually(实际上) defenceless and , in fact, often seem to be hypnotized（恍惚) by approaching predators(捕食动物的动物). When this happens, they crouch(蹲伏) squealing（尖叫) and make no attempt to run away.Only their extraordiary fertility(繁殖力) has enabled them to survive the onslaughts of foxes, badgers, wild cats, martens, stoats, weasels, polecats, dogs, man and disease.
Why Do Some Elephants Have Very Large Ears?
African elephants have larger ears than Indian, or Asiatic, elephants because they live in hotter conditions and are bigger and even aggressive and active. The huge ears of the African elephant, sometimes three and a half feet wide, enable it to hear more acutely(敏锐). When the animal charges its fans out its ears, augmenting(使扩大) its terrible appearance and striking fear into the heart of any enemy.
The ears also present a large surface for losing body-heat. African elephants, who are at a disadvantage(不利) in the heat because of their large size, wave their ears to keep cool and to chase away flies. The African elephant is the biggest and noblest of land animals, reaching a height of 11 feet and a weight of nearly six tons.
The Asiatic elephant is smaller. It inhabits(栖居) the forests of south-east Asia from India to Sri Lanka and Kalimantan. It does not like heat and seeks the deep shade of the forest.
When Does a Chameleon Change Colour?
A chameleon(变色龙) will change colour when it senses danger.The remarkable member of the lizard family(蜥蜴类动物) can change colour to match its background(变出同周围事物同样的颜色) or , at least, to become almost unrecognizable.
The ranges of colours and patterns of the various species(种类) differ widely, but most chameleons can become yellow or cream, green or dark brown. They can also adapt(适应) spots either dark or light depending on the colour of the ground.
Apart from its response(反应) to danger, the chameleon will change colour according to the light and temperature. This mechanism(技能) is controlled from the nervous system and involves(包括) the dispersion(消散) or concentration of colour pigments(色素) in the creature?蒺s skin.
When Does Sharks Attack Humans?
Some sharks(鲨鱼) may attack human beings if attracted by underwater noises, the presence of a large number of bathers(游泳者), or the glint(闪耀，反射) of jewellery or some other article. But probably the greatest provocation(刺激) to a shark is the presence of blood, for example from a spread fish or live bait(饵).
Sharks are most likely to attack during the daytime, the areas of greatest danger being those where the sea temperature is between 16° and 21° Centigrade. Most attacts seem to occur(发生) about 200 to 300 feet from the shore where the water is shallow— or no more than two or three feet in depth.
Among the kinds of sharks known to attack human beings are tiger and the blue and grey nurse sharks. The most feared of the shark family is the great white shark, a powerful and aggressive（攻击性强的） creature.