鳄鱼 Crocodile

鱷魚（英语：crocodilia），屬於蜥形綱鱷目。分佈於熱帶到亞熱帶的河川、湖泊、海岸中，現存24種。長吻銳齒、四肢短小、尾巴扁平有力、皮硬厚鱗。棲於熱帶河流沼澤，並很少離開水過遠的地方。食肉為主。卵生。

鳄鱼拥有较强的免疫力，能够防止鳄鱼在险恶环境下，与掠夺者搏斗后留下的伤痕产生致命感染。曾有科学家们发现鳄鱼强大的免疫系统可以杀灭艾滋病毒（HIV），研究人员发现鳄鱼血液中所含的某些蛋白质能够杀死对盘尼西林有抗药性的细菌，例如金黄葡萄球菌^[1]。

鳄鱼的心脏和人类一样有心房（左心房、右心房）和两室（左心室、右心室），是脊椎动物中首次出现的左右心室完全分隔。（两栖动物和除鳄鱼以外的爬行动物都只有一个心室，或没有完全分隔的左右心室。）脊椎动物中只有鳄鱼、鸟类、哺乳动物有左右心室完全分隔的心脏。

鱷魚壽命多在45-100年的範圍間，平均為75年。根據部分考古學家研究發現，古代鱷魚體長最長達到12米。

鳄鱼是一种曾经和恐龙同时存在的动物，但超强的适应力使它存活至今。

Crocodiles (subfamily Crocodylinae) or true crocodiles are large aquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily. A broader sense of the term crocodile, Crocodylidae that includes Tomistoma, is not used in this article. The term crocodile here applies only to the species within the subfamily of Crocodylinae. The term is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes Tomistoma, the alligators and caimans (family Alligatoridae), the gharials(family Gavialidae), and all other living and fossil Crocodylomorpha.

Although they appear to be similar to the untrained eye, crocodiles, alligators and the gharial belong to separate biological families. The gharial having a narrow snoutis easier to distinguish, while morphological differences are more difficult to spot in crocodiles and alligators. The most obvious external differences are visible in the head with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans. Another obvious trait is the upper and lower jaws of the crocodiles are the same width, and teeth in the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore all teeth are visible unlike an alligator; which possesses small depressions in the upper jaw where the lower teeth fit into. Also when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define the family that the species belongs to.^[1] Crocodiles have more webbing on the toes of the hind feet and can better tolerate saltwater due to specialized salt glands for filtering out salt, which are present but non-functioning in alligators. Another trait that separates crocodiles from other crocodilians is their much higher levels ofaggression.^[2]

Crocodile size, morphology, behavior and ecology somewhat differs between species. However, they have many similarities in these areas as well. All crocodiles aresemiaquatic and tend to congregate in freshwater habitats such as rivers, lakes, wetlands and sometimes in brackish water and saltwater. They are carnivorousanimals, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as molluscs and crustaceans, depending on species and age. All crocodiles are tropical species that unlike alligators, are very sensitive to cold. They first separated from other crocodilians during the Eoceneepoch, about 55 million years ago.^[3] Many species are at the risk of extinction, some being classified as critically endangered.

马来貘 Tapir

馬來貘（学名：Tapirus indicus）又叫亚洲貘、印度貘，是貘屬下的一個種，屬於奇蹄目貘科。馬來貘為中大型哺乳動物，前肢有四趾，後肢有三趾。一般而言，馬來貘體長為1.8至2.2公尺之間，站立高度有90至105公分高，成體一般重量約在230至310公斤之間，最大个体可以达到400公斤；雌性的馬來貘通常比雄性的體型來得大，身體渾圓可愛，皮厚毛硬，全身除中後段有如穿著肚兜、包著尿布的白色體毛外，其牠部位皆呈黑色。小貘出生時，身體有條紋狀的保護色、棕毛。其貌「似豬不是豬、似象不是象」，故也有古書稱之「四不像」^{[註 1]}。

A tapir (/ˈteɪpər/ tay-pər or /təˈpɪər/ tə-peer) is a large herbivorous mammal, similar in shape to a pig, with a short, prehensile snout. Tapirs inhabit jungle and forest regions ofSouth America, Central America, and Southeastern Asia. The five extant species of tapirs are the Brazilian tapir, the Malayan tapir, the Baird's tapir, the kabomani tapir, and themountain tapir. The four species that have been evaluated (the Brazilian, Malayan, Baird's and mountain tapir) have all been classified as endangered or vulnerable. Their closest relatives are the other odd-toed ungulates, including horses and rhinoceroses.

马 Horse

马（学名：Equus ferus caballus），是一种草食性家畜，广泛分布于世界各地，原产于中亚草原，4000多年前就被人类驯養，15世纪后，才被歐洲殖民者带到美洲和澳洲地區。马耳小而直立，面部长；额、颈上有长鬃，尾有長毛，四肢强健，内侧有附蝉，第三趾最发达，趾端有馬蹄，其余各趾退化；毛色复杂，有骝、栗、青、黑等。

Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although only eightspecies of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia.

Common characteristics of modern bears include large bodies with stocky legs, long snouts, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous with varied diets.

With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They are generally diurnal, but may be active during the night (nocturnal) or twilight (crepuscular), particularly around humans. Bears possess an excellent sense of smell and, despite their heavy build and awkward gait, are adept runners, climbers, and swimmers. In autumn, some bear species forage large amounts of fermented fruits, which affects their behaviour.^[1] Bears use shelters, such as caves and burrows, as their dens; most species occupy their dens during the winter for a long period (up to 100 days) of sleep similar to hibernation.^[2]

Bears have been hunted since prehistoric times for their meat and fur. With their tremendous physical presence and charisma, they play a prominent role in the Arts,mythology, and other cultural aspects of various human societies. In modern times, the bears' existence has been pressured through the encroachment on their habitats and the illegal trade of bears and bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.

熊 Bear

熊，是一种大型哺乳類，属于食肉目犬形亚目熊科，现存进化关系最近的物种是鳍足类（海狮、海豹、海象）和犬科。现在地球上有八种熊，广泛分布北半球和南半球的一部分，如亚洲、欧洲、美洲和北极。

常见的特征是身躯庞大、四肢粗壮有力、长鼻子、厚毛发、短尾、跖行足、每只脚爪上有五个弯曲锋利不能回缩的爪子（对比猫科动物的爪子是可以回缩的）。北极熊基本是食肉动物，而其他的熊都是杂食动物。

除去母亲带小熊的情况，一般是独自行动。昼出夜伏，不过也会夜晚或黎明活动，特别是在人类附近的时候。嗅觉极其灵敏，看似笨拙，实际奔跑速度极快，时速可达40km/h，耐力超群，而且可以适应各种气候和地形。在秋天，熊吃了发酵的果子会表现出醉态。^[1]熊需要一个掩蔽所，如一个山洞或树洞，以供冬季在其中冬眠，冬眠有时会长达100天。^[2]

史前人类就有捕猎熊的历史，为了获取它们的肉和毛皮。它们的形象经常出现在神话传说、文学、艺术中。但在现代社会，因为栖息地减少和非法的熊制品贸易，熊面临着灭绝的压力。国际动物保护组织称有六种熊处于危险至濒危级别，棕熊在有些地区已经灭绝。

Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although only eightspecies of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia.

Common characteristics of modern bears include large bodies with stocky legs, long snouts, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous with varied diets.

With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They are generally diurnal, but may be active during the night (nocturnal) or twilight (crepuscular), particularly around humans. Bears possess an excellent sense of smell and, despite their heavy build and awkward gait, are adept runners, climbers, and swimmers. In autumn, some bear species forage large amounts of fermented fruits, which affects their behaviour.^[1] Bears use shelters, such as caves and burrows, as their dens; most species occupy their dens during the winter for a long period (up to 100 days) of sleep similar to hibernation.^[2]

Bears have been hunted since prehistoric times for their meat and fur. With their tremendous physical presence and charisma, they play a prominent role in the Arts,mythology, and other cultural aspects of various human societies. In modern times, the bears' existence has been pressured through the encroachment on their habitats and the illegal trade of bears and bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.

长颈鹿

长颈鹿（学名：Giraffa camelopardalis）是一种生长在非洲的反刍偶蹄动物，是世界上最高的陆生动物。雄性个体高达4.8到5.5米高，重达900公斤。雌性个体一般要小一些。

长颈鹿是非洲特有的动物，与鹿和牛有亲缘关系，但属于不同的科，即长颈鹿科。长颈鹿科包括长颈鹿和霍加狓两种动物。

长颈鹿的种加词为camelopardalis，源于早期罗马帝国时期人们给它起的名字，意思是骆驼和豹的杂交体，因为它的外形类似这两种动物的揉合体。

中国明朝时郑和的船队航行到东非，曾带两只长颈鹿回到北京，被当时的人们认为是麒麟。明成祖以此祥瑞之兆来表明自己施政的伟大。時至今日，日語及韓語仍將長頸鹿稱作麒麟，台語也將「長頸鹿」稱作「麒麟鹿」。

中国典籍关于长颈鹿的记载，最早出自晋代李石所著《续博物志》，记录非洲索马里沿岸拨拔力古国出产的异兽,身高一丈余颈长九尺。宋代赵汝适著《诸蕃志》中称非洲长颈鹿为徂蜡：“状如驼驰，而大如牛，色黄，前脚高五尺，后低三尺，头高向上”。

大象 Elephant

象，通称大象，是目前陆地上最大的哺乳动物，屬於长鼻目，只有一科两属三种，即象科（学名：Elephantidae），非洲象屬和象屬，非洲象有两种：普通非洲象（也叫热带草原象或灌木象）和非洲森林象，象屬只有亚洲象一种（也叫印度象）。广泛分布在非洲撒哈拉沙漠以南和南亚及东南亚以至中国南部边境的热带及亚热带地区。

象的妊娠期为22个月，刚出生的小象就有100千克重，需要8-14岁才能达到性成熟。

象皮厚毛少，鼻与上唇愈合成圆筒状长鼻，两个上颌门齿大而长，就是所谓的“象牙”，口中一般每侧有三个前磨牙和三个后磨牙，食用高纤维的食品，树叶、草类等，磨牙并不是同时长出，现存的磨牙磨损后，新的磨牙才长出来，所以如果最后一颗（第六颗）磨牙大约在60岁以后磨损后，老象可能死于营养不良，如果继续饲喂磨碎的食品，它有可能继续活下去。

Elephants are large mammals of the family Elephantidae and the order Proboscidea. Two species are traditionally recognised, the African elephant (Loxodonta africana) and the Asian elephant (Elephas maximus), although some evidence suggests that African bush elephants and African forest elephants are separate species (L. africana andL. cyclotis respectively). Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia. Elephantidae is the only surviving family of the order Proboscidea; other, now extinct, members of the order include deinotheres, gomphotheres, mammoths, and mastodons. Male African elephants are the largest extantterrestrial animals and can reach a height of 4 m (13 ft) and weigh 7,000 kg (15,000 lb). All elephants have several distinctive features the most notable of which is a long trunk or proboscis, used for many purposes, particularly breathing, lifting water and grasping objects. Their incisors grow into tusks, which can serve as weapons and as tools for moving objects and digging. Elephants' large ear flaps help to control their body temperature. Their pillar-like legs can carry their great weight. African elephants have larger ears and concave backs while Asian elephants have smaller ears and convex or level backs.

Elephants are herbivorous and can be found in different habitats including savannahs, forests, deserts and marshes. They prefer to stay near water. They are considered to bekeystone species due to their impact on their environments. Other animals tend to keep their distance; predators such as lions, tigers, hyenas and wild dogs usually target only the young elephants (or "calves"). Females ("cows") tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups are led by an individual known as the matriarch, often the oldest cow. Elephants have a fission-fusion society in which multiple family groups come together to socialise. Males ("bulls") leave their family groups when they reach puberty, and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate and enter a state of increased testosterone and aggression known as musth, which helps them gain dominance and reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to haveself-awareness and show empathy for dying or dead individuals of their kind.

African elephants are listed as vulnerable by the International Union for Conservation of Nature (IUCN), while the Asian elephant is classed as endangered. One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past they were used in war; today, they are often put on display in zoos and circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature and popular culture.

鲸鱼 Whale

鲸是海洋哺乳動物中鲸目生物的俗名，又分為齒鯨類（Odontoceti）和鬚鯨類(Mystacoceti)鲸目之下包括有海豚科。但在日常语言中，人们将鲸和海豚分开。鲸往往被俗称为鲸鱼，但实际上鲸并不是一种鱼。海豚科屬於鲸目下的齒鯨亞目，該亞目中有抹香鯨及白鯨等。而以鯨鬚替代牙齒，利用鲸须過濾水中浮游生物進食的鬚鯨亞目，有座頭鯨及現存地球上最大的動物藍鯨等。

數世紀以來，鯨經常被作為桌上佳餚或是工業產品的原料。然而，到了20世紀中葉，鯨的數量已經因為捕鯨工業的盛行而銳減，成為了瀕臨絕種的生物。所幸現階段大多數國家都已經在八零年代簽下全球禁捕令，停止捕鯨工業的持續發展。

Whales are a widely distributed and diverse group of fully aquatic marine mammals. They comprise the extant families Cetotheriidae (whose only living member is the pygmy right whale), Balaenopteridae (the rorquals), Balaenidae (right whales), Eschrichtiidae (the gray whale), Monodontidae (belugas and narwhals), Physeteridae (the sperm whale), Kogiidae (the dwarf and pygmy sperm whale), and Ziphiidae (the beaked whales).^[1][2][3] There are 40 extant species of whales. The two suborders of whales, Mysticeti and Odontoceti, are thought to have split up around 34 million years ago.^[4] Whales belong to the clade Cetartiodactyla and their closest living relative is the hippo having diverged about 40 million years ago.^[5]

Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 34 metres (112 ft) and 190 metric tons (210 short tons) blue whale, which is also the largest creature on earth. Several species exhibit sexual dimorphism, in that the females are larger than males. They have streamlined bodies and two limbs that are modified into flippers. Though not as flexible or agile as seals, whales can go at incredibly fast speeds, up to 20 knots. Balaenopterids (rorquals) use their throat pleats to expand their mouth to take in huge gulps of water.^[6] Balaenids have huge heads that can make up 40% of their body mass to take in huge amounts of water.^[7] Odontocetes have conical teeth designed for catching fish or squid. Mysticetes have a well developed sense of "smell", whereas Odontocetes have well-developed senses—their hearing that is adapted for both air and water, and can survive even if they're blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.

Although whales are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres, and migrate to the equator to give birth. Odontocetes feed largely on fish and squid; but a few, like the sperm whale, feed on large invertebrates, such as giant squid.^[8] Grey whales are specialized for feeding on bottom-dwelling mollusks.^[9] Male whales typically mate with multiple female every year, but females only mate every two to three years.^[10] Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Whales produce a number of vocalizations, notably the songs of the humpback whale.^[1]

The meat, blubber and baleen of whales have traditionally been used by indigenous peoples of the Arctic. Whales have been depicted in various cultures worldwide, notably, the Inuit and the coastal peoples of Vietnam and Ghana; they sometimes hold whale funerals.^[11] Small whales, such as belugas, are commonly kept in captivity and are even sometimes trained to perform tricks. Once relentlessly hunted by commercial industries for their products, whales are now protected by international law. The North atlantic right whales have become nearly extinct in the past century with a population of 450, and the north pacific grey whale population is ranked Critically Endangered by the IUCN.^[12] Besides whaling, they also face threats from bycatch and marine pollution (anything from trash bags to oil contamination).^[1][13]