The animal kingdom has long been a mysterious one for humans and every day we learn something new about it. This is a list of ten little known facts about animals.
10. Crocodiles Eat Stones
The stomach of a crocodile is a rocky place to be, for more than one reason. To begin with, a croc’s digestive system encounters everything from turtles, fish and birds to giraffes, buffaloes, lions and even (when defending territory) other crocodiles. In addition to that bellyful-o’-ecosystem, rocks show up too. The reptiles swallow large stones that stay permanently in their bellies. It’s been suggested these are used for ballast in diving.
9. Whale Milk is 50% Fat
Nursing a newborn is no “small” feat for the whale, whose calf emerges, after 10 to 12 months in the womb, about a third the mother’s length (that’s a 30-foot baby for the Blue whale). The mother squirts milk into the newborn’s mouth using muscles around the mammary gland while the baby holds tight to a nipple (yes, whales have them). At nearly 50 percent fat, whale milk has around 10 times the fat content of human milk, which helps calves achieve some serious growth spurtseas much as 200 pounds per day.
8. Birds Recognize Landmarks
Can you imagine a road trip vacation without missed exits, stubborn drivers or map-folding disasters? Of course noteyou’re not a bird. Pigeons can fly thousands of miles to find the same roosting spot with no navigational difficulties. Some species of birds, like the Arctic tern, make a 25,000 mile round-trip journey every year. Many species use built-in ferromagnets to detect their orientation with respect to the Earth’s magnetic field. A November 2006 study published in Animal Behaviour suggests that pigeons also use familiar landmarks on the ground below to help find their way home
7. Beavers have Longer Days in Winter
Beavers become near shut-ins during winter, living off of previously stored food or the deposits of fat in their distinctive tails. They conserve energy by avoiding the cold outdoors, opting instead to remain in dark lodgings inside their pile of wood and mud. As a result these rodents, which normally emerge at sunset and turn in at sunrise, have no light cues to entrain their sleep cycle. The beaver’s biological sense of time shifts, and she develops a “free running circadian rhythm” of 29-hour days.
6. Mole-Rats are not Blind
With their puny eyes and underground lifestyle, African mole-rats have long been considered the Mr. Magoos of rodents, detecting little light and, it has been suggested, using their eyes more for sensing changes in air currents than for actual vision. But findings of the past few years have shown that African mole-rats have a keen, if limited, sense of sight. And they don’t like what they see, according to a report in the November 2006 Animal Behaviour. Light may suggest that a predator has broken into a tunnel, which could explain why subterranean diggers developed sight in the first place.
5. Baby Chicks are Altruistic
It’s a mistake to think of evolution as producing selfish animals concerned only with their own survival. Altruism abounds in cases where a helping hand will encourage the survival of genetic material similar to one’s own. Baby chicks practice this “kin selection” by making a special chirp while feeding. This call announces the food find to nearby chicks, who are probably close relations and so share many of the chick’s genes. The key to natural selection isn’t survival of the fittest animal. It’s survival of the fittest genetic material, and so brotherly behavior that favors close relations will thrive.
4. Many Fish Swap Sex Organs
With so many land creatures to wonder at, it’s easy to forget that some of the weirdest activities take place deep in the ocean. The strange practice of hermaphroditism is more common among species of fish than within any other group of vertebrates. Some fish change sex in response to hormonal cycle or environmental changes. Others simultaneously possess both male and female sex organs.
3. Giraffes have Unique Blood Flow
The stately giraffe, whose head sits some 16 feet up atop an unlikely pedestal, adapted his long neck to compete for foliage with other grazers. While the advantage of reach is obvious, some difficulties arise at such a height. The heart must pump twice as hard as a cow’s to get blood up to the brain, and a complex blood vessel system is needed to ensure that blood doesn’t rush to the head when bent over. Six feet below the heart, the skin of the legs must then be extremely tight to prevent blood from pooling at the hooves.
2. Elephants are Smart
Elephants have the largest brain, nearly 11 pounds on average of any mammal that ever walked the earth. Do they use that gray matter to the fullest? Intelligence is hard to quantify in humans or animals, but the encephalization quotient (EQ), a ratio of an animal’s observed brain size to the expected brain size given the animal’s mass, correlates well with an ability to navigate novel challenges and obstacles. The average elephant EQ is 1.88. (Humans range from 7.33 to 7.69, chimpanzees average 2.45, pigs 0.27.) Intelligence and memory are thought to go hand in hand, suggesting that elephant memories, while not infallible, are quite good.
1. Parrots Understand
Parrot speech is commonly regarded as the brainless squawking of a feathered voice recorder. But studies over the past 30 years continually show that parrots engage in much more than mere mimicry. Our avian friends can solve certain linguistic processing tasks as deftly as 4-6 year-old children. Parrots appear to grasp concepts like “same” and “different”, “bigger” and “smaller”, “none” and numbers. Perhaps most interestingly, they can combine labels and phrases in novel ways. A January 2007 study in Language Sciences suggests using patterns of parrot speech learning to develop artificial speech skills in robots.
译文:
动物的十大特异功能（图）
动物王国对人类世界来说一直是个未解之谜。每天，我们都从中获得新发现。以下介绍的十种动物的特异功能只是我们所了解的一小部分。
第10名 鳄鱼吞石
由于许多原因，鳄鱼的胃犹如岩石般坚韧。当任何龟、鱼类、鸟类、长颈鹿、水牛、狮子、其他鳄鱼（在捍卫领土时）身体部位通过鳄鱼的消化系统时，鳄鱼不死的身体系统和他体内的岩石体质便发挥了作用，爬虫燕子变成的大量石头永久存在于它的肚子之中。这种情况被认为在鳄鱼游泳时的起到了镇流器的作用。
第9名 鲸鱼乳汁富含50%脂肪
在鲸鱼世界中，抚养一头新出生的小鲸鱼是一个伟大的壮举，小鲸鱼在出生前会在母亲的子宫中待上10到12个月，它的身长相当于母亲身长的三分之一（幼年蓝鲸体形相当于30英尺）。母鲸利用乳腺周围的肌肉将乳汁喷射入幼鲸的口中，与此同时，幼鲸也会将舌头放在母亲的乳头周围（是的，鲸鱼也有乳头）。鲸鱼乳汁犹如50%的身体脂肪，其脂肪含量相当于人类的10倍，这能帮助幼鲸每天以增加200磅体重的速度成长。
第8名 鸟儿寻家的本领
能想象在外地度假时，你能避免错过出入口、不遇上顽固的司机、还有遭到地图折叠灾害吗？当然不可能，因为你不是一只鸟。鸽子可以飞翔数千英里来寻找同一个栖息地而没有任何航行困难。有些种类的鸟儿，例如北极燕鸥，能进行每年2万5千英里的循环飞行。许多种类的鸟儿更有内置式指南针，可以根据地球的磁场来侦察飞行方向。一份2006年发表的动物行为研究报告指出，鸽子还能利用对陆地下面的熟悉来帮助找到自己的家园。
第7名 海狸的漫长冬日
海狸到了冬天就会冬眠，他们会依靠原先储存的食物来生存，除此以外还有他们那个独特的尾巴里特别储存的脂肪。他们节约能源，避免受到室外的寒冷，反而选择留在黑暗的住所内，里面包含的了许多的椿木和泥。由于这些海狸一般会在太阳升起或者有日照的情况下活跃起来，所以并不能根据原来的线索来确定它们的睡眠周期。海狸的生物钟使得他自行拟定了一种29个小时一天的“自由运行规律”
第6名 摩尔老鼠不盲
非洲的摩尔老鼠虽然有着微不足道的眼睛和地下生活的环境状态，他们一直被认为是老鼠中的麦奇先生，据说，他们能用自己小小的眼睛来检测微弱的光线，眼睛能根据气流的改变传达感应，达到实际的视力效果。但是过去这些年的研究也表明非洲摩尔老鼠也会有热衷的事物，他们会限制自己的感觉视线.而且他们并不喜欢自己所看到的，2006年11月的动物行为报告指出，光线就意味着捕食者可能闯入了摩尔老鼠的地下隧道，这便解释了为什么摩尔老鼠的地下发达视线是第一位的。
第5名 小雏鸡的利他行为
一直以来有一个错误的观点，认为动物只关注自己的生存而会产生自私的行为。在利他主义充斥的情况下，有一个观点帮助指出，利他主义基因是存在于动物的遗传物质之中的。小雏鸡实践出一种“亲近选择”，他们通过发出不同的啁啾来让母亲饲喂。这可以帮助母亲找到附近的雏鸡来饲喂，这些雏鸡都有着亲密的关系，能够将食物互相分享，自然的选择并不是优胜略汰，而是遗传物质的竞争，所以互相帮助的行为能够使得密切关系基因得到蓬勃发展。
第4名 鱼类变换性器官
当我们看到许多陆地上的猛禽时，很容易便忽视了有许多怪异的活动是发生在海洋深处的。有一种奇怪的现象就是鱼类的两性畸形，比起其它种类的脊椎动物，这在鱼类物种中较为常见。有些鱼根据自己的荷尔蒙周期以及环境的改变来改变自身性别。其他还有一些鱼类同时具有男女两套性器官。
第3名 长颈鹿的独特血流
庄严的长颈鹿，头部压在看起来并不能担当底座的16英尺长的脖子上，从长长的脖子上方，可以吃到树叶和观看到农牧里其他的植物。虽优势明显但也会因为高度而出现一些问题。与奶牛相比，长颈鹿的心脏要泵血两倍的量才能将血液输送到大脑，这形成成了一个复杂的血液系统，以确保血液在其弯腰低头的时候不会一下猛冲入大脑，心脏的6英尺以下是腿部的皮肤，这些皮肤必须保持极度紧张来阻止血液汇集的脚蹄部位。
第2名 聪明的大象
大象的脑部最大，将近11磅，是陆地上的哺乳动物有史以来最大的。里面是用石头装满的马？动物和人类的智慧是很难估量的，但是EQ，一个动物脑部的大小正常比例与你预期的大小比例可以告诉我们动物的族群的大小，这与动物的特殊表现和有挑战性的举动有关。大象的平均EQ是1.88（人类的平均EQ在7.33至7.69的范围内，黑猩猩在2.45至0.27的范围内），智力和记忆思维齐头并进，这告诉我们，大象的记忆，不是错误的，而是很好的。
第1名 鹦鹉的理解能力
鹦鹉学舌，一般我们通常认为鹦鹉有着语言录音机的功能。但是过去30年的研究表明，鹦鹉并不是从事单纯的模仿。我们的小鸟朋友能够像4到5岁的儿童一样解决某些语言处理问题。看起来，鹦鹉能够把握某些概念例如：“相同”和“不同”、“大”和“小”“没有”和“有”，有趣的是，他们可以用新颖的方式组合单词和词组。一份2007年1月学习语言科学的调查建议可以采用鹦鹉学舌的方法来研究发展人工语音技能的机器人。