它们看起来像鱼但它们是哺乳动物。
一些动物生下来时吃它们的妈妈的奶。它们是哺乳动物。
Some animals drink milk from their mommy when they were new born, and they are mammals.
虽然我只是提到了狒狒和八哥，但是它们是哺乳动物和禽类的代表。
Granted, I've only mentioned baboons and starlings, but there you've got a mammalian representative and an avian one.
它们是哺乳动物的杰出代表，像蜜蜂一样过群居生活，和蚂蚁、蜜蜂、黄蜂以及白蚁一样有组织。
They are uniquely eusocial amongst mammals, meaning they are hive-like and massively organized creatures like ants, bees, wasps and termites only much much larger and scarier looking.
“老鼠是比鸟更好的实验材料，因为它们是哺乳动物，并且它们的大脑结构和其它生物学特征和人类的更相近，”内村说。
"Mice are better than birds to study because they are mammals and much closer to humans in their brain structures and other biological aspects," Uchimura said.
蝙蝠是唯一能飞很远的哺乳动物，但它们还有另一种能力。
Bats are the only mammals that can fly a great distance, but they have another ability.
与许多哺乳动物不同的是，它们不会做出类似人类的行为。
Unlike many mammals they do not engage in human-like behaviour.
数量的周期循环是小型哺乳动物的特征，它们有时似乎是由捕食者造成的。
Population cycles are characteristic of small mammals, and they sometimes appear to be brought about by predators.
其他哺乳动物如鸭嘴兽和一些鼩鼱是有毒的，这意味着它们会在体内产生一种毒素。
Other mammals, such as the platypus and some shrews, are venomous, meaning they produce a toxin internally .
海牛是生活在佛罗里达河流和沿海水域的水生哺乳动物，它们游到海面附近，经常在与船只相撞时被撞死。
Manatees, aquatic mammals inhabiting Florida's rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats.
松鼠面临的一个挑战是，因为它们体型小，出汗会使它们失去太多水分，其他许多小型哺乳动物也面临着这样的问题。
One challenge that squirrels face, well many small mammals do, is that because of their size, sweating would make them lose too much moisture.
另外，小型哺乳动物，如老鼠和地松鼠是许多水禽捕食者的重要食物，它们自己也可能是鸣禽网的重要捕食者。
Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest predators and can themselves be important predators of songbird nets.
它们是一组引起哺乳动物和鸟类疾病的病毒。
They are a group of viruses that cause diseases in mammals and birds.
哺乳动物中的红细胞成熟时是无核的，这意味着它们缺乏细胞核。
Erythrocytes in mammals are anucleate when mature, meaning that they lack a cell nucleus.
萨曼塔·普莱斯：蓝鲸可能是有史以来最大的哺乳动物，它们的猎物——磷虾及浮游生物——体型却非常微小，几乎用显微镜才能看见。
Samantha Price: The blue whale which is –we think –is probably the largest ever living mammal… eats these tiny, almost microscopic krill and plankton.
恐龙的骨骼结构表明它们不同于现代的爬行动物，它们的生长速度像鸟类和哺乳动物一样快这与越来越多证明恐龙是温血动物的证据相吻合。
The bone structure of dinosaurs shows that, unlike modern reptiles, they grew as fast as birds and mammals — which dovetails with a growing body of evidence that dinos were, in fact, warm-blooded.
它们也是地球上最多产的哺乳动物——哺乳动物中五分之一是蝙蝠。
They are also the most abundant mammal on the planet - one in five mammals is a bat.
鸣鸟的骨头可能是中空的，但是它们实际上比相同大小的哺乳动物的骨头的密度要大得多。
Songbird bones may be hollow, but they're actually denser than the bones of mammals of the same size.
研究者在文中指出，虽然北极熊是海洋哺乳动物，它们从海洋中获取食物(如海豹)；可是它们不是水栖哺乳动物。
The researchers write that although polar bears are Marine mammals, in that they derive their nutrition from the ocean (i.e. they eat seals), they are not aquatic mammals.
假如捕食者是个哺乳动物(具备听力)，它们就发出呼叫。
If the predator is a mammal (which can hear), they utter alarm calls.
尽管考拉是澳大利亚最具有代表性的哺乳动物，但由于栖息地的减少，它们仍处在危险中。
Though koalas are Australia's most iconic and adored marsupials, they are under threat due to a shortage of suitable habitat from mass land clearance.
然而令人不安的是，这些数字很可能只是一个保守的估计。因为科学家们对哺乳动物中的836个种类还缺乏足够的数据，甚至无法按照它们受威胁的程度来归类。
Disturbingly, the figures are likely to be a conservative estimate, because scientists have insufficient data on 836 species to even classify how threatened they are.
他们这么说的原因是狗狗们更勤地使用大脑，因为像它们那样友好的、社会型的哺乳动物的大脑比那些喜欢独处的、冷漠的动物拥有更多的灰质。
The reason, they claim, is that dogs evolved bigger brains because friendly, social mammals need more grey matter than solitary, aloof ones.
由此可见，这些Toll样受体在进化中是相当古老的，虽然它们在哺乳动物中的数量已经增长到大约一打了。
Thus, Toll-like receptors are evolutionarily ancient, although their number in mammals has grown to about one dozen.
它们是世界上唯一的两种产卵的哺乳动物。
它们是世界上唯一的两种产卵的哺乳动物。
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