Sorry, guys! Do you ever have one of those days where you just don't have the energy to do all that much? And when you do move, you move really slowly? Well, that's pretty much what every day is like for a sloth.
抱歉啦，大家!你曾有過就是沒勁做太多事那樣的一天嗎？然後當你真的動起來時，你動得超級慢？這個嘛，樹懶的每天基本上就是那樣。
Sloths are the slowest mammals on Earth. Just how slow are they? Well, it can take a sloth up to an entire month to travel a single mile on the ground. But that's okay, because sloths spend most of their lives in the trees, where they can move just a little bit faster. Their powerful arms and curved claws let them move easily from branch to branch in the rainforests of Central and South America, where they're from.
樹懶是地球上最慢的哺乳類動物。牠們到底有多慢呢？嗯，光要在地上移動一英哩最久就可以花上樹懶整整一個月。不過沒關係，因為樹懶一輩子大多待在樹上，牠們在樹上就可以動得稍微快一點點。樹懶有力的雙臂和彎曲的爪子讓牠們能輕鬆地在中南美洲雨林的樹間移動，那裡是牠們的故鄉。
Sloths are identified by the number of claws that they have on their front feet. There are two-toed sloths and three-toed sloths. But good luck actually spotting a sloth swinging through the trees. These guys spend very little time moving and a whole lot of time sleeping and eating. Sounds sort of boring, doesn't it? Wrong! If you ask me, sloths are super cool! They're not lazy—they're just really good at conserving, or saving, their energy.
樹懶被用前腳爪子的數目作辨別。有二趾樹懶和三趾樹懶。但要真的目睹樹懶在樹間擺盪可得祝你好運了。這些傢伙花很少時間移動，但花一堆時間睡和吃。聽起來有點無聊，對吧？錯!如果你問我，樹懶可是超級酷的!牠們不是懶－－牠們只是很會儲存，或節省牠們的能量。
Their diet of leaves and bark doesn't provide them with a whole lot of nutrition, so they need to save as much energy as they can. And one way sloths manage to conserve their energy is by keeping their food in their bodies for as long as possible. Sloths have big stomachs that can hold a large amount of food. While it might take you or I just a few hours to digest our breakfast, it can take a sloth 30 days to digest a single leaf. Since they digest their food so slowly, sloths don't get a lot of energy very quickly from their food, but they also don't use a lot of energy to break it down. Plus, because their stomachs work so slowly, they don't need to go to the bathroom as often as we do. In fact, one of the few times that three-toed sloths come down from the trees is for their weekly potty break. Once a week—that's it!
樹懶的樹葉和樹皮餐沒有提供牠們太多營養，所以牠們得盡可能儲存能量。而樹懶儲存能量的一種方法是將食物存在體內越久越好。樹懶有著可以裝下很多食物的大胃。雖然你和我可能只要花幾個小時就能把早餐消化掉，但要消化掉一片葉子可以花上樹懶三十天。因為牠們消化食物的速度那麼慢，樹懶並不會非常快速地從食物獲得很多能量，不過牠們也不會耗很多能量來分解食物。此外，因為牠們的胃運作得如此緩慢，牠們不用和我們一樣常去廁所。事實上，三趾樹懶從樹上下來幾次的其中一次就是要跑一週一次的廁所。一週一次－－就那樣!
Another weird way sloths conserve energy is by having a naturally low body temperature. If our body temperature changes more than three degrees, it probably means that we're sick, but that's not so for the two-toed sloth. It has the lowest body temperature of any mammal in the world. It can dip as low as 30 degrees Celsius. Most mammals, including us, have body temperatures of 36 degrees Celsius or higher. After all, it takes a lot of energy to keep your body warm. So when sloths aren't active, which is most of the time, their bodies just automatically switch into low-energy mode, and their body temperature drops.
另一個樹懶保存能量的奇怪方式是天生就低的體溫。如果我們的體溫變化超過三度，那很可能代表我們病了，但對二趾樹懶來說卻不是那樣。二趾樹懶有全世界任何哺乳類動物中最低的體溫。那可以降到攝氏三十度那麼低。多數哺乳類動物，包含我們，都有著攝氏三十六度或者再更高的體溫。畢竟，要保持身體溫暖得消耗很多能量。所以當樹懶不活躍時，也就是大多時候，牠們的身體就會自動切換到低耗能模式，然後牠們的體溫就會下降。
The last weird way that sloths save energy is my personal favorite. Three-toed sloths are the only mammal that can rotate their heads almost all the way around their bodies, like owls do. This is because they have more vertebrae, or bones in their neck, than other mammals do. This cool trick helps them look for food and keep an eye out for predators without having to go anywhere or do anything. They can just hang out and twist their head around observing the world around them.
最後一個樹懶省力氣的奇怪方式是我個人最喜歡的。三趾樹懶是唯一一種可以讓頭幾乎在身體上轉一圈的哺乳類動物，就像貓頭鷹一樣。這是因為牠們比其他哺乳類動物有著更多脊椎骨，或者說是脖子的骨頭。這項超酷技能幫助牠們找食物還有留意掠食者，但卻不用去任何地方或做任何事。牠們可以就打發時間，然後轉轉頭觀察週遭的世界。
So, sure, sloths are slow, but not because they're lazy. They have just adapted to a nice, mellow, low-energy lifestyle that works out well for them. They're basically the ultimate energy-saving machine.
所以，沒錯，樹懶很慢，但不是因為牠們懶。牠們只是習慣一種和牠們很合得來，輕鬆愉快又省力的生活風格。牠們基本上是終極節能機器。
Thanks for joining us on SciShow Kids! I'm Jessi, this is Squeaks, and we'll see you next time.
謝謝收看《小朋友科學秀》!我是潔西，這是吱吱，我們下回見。
