2017年4月19日 星期三

長頸鹿的不可思議 amazing giraffes


世界上奇妙的生物千千百百種,但是這種可能你一時之間也想不出來,但是它身上可是有著很多另人驚奇的設計,甚至在日文、韓語和台語中,被稱作是麒麟呢!它就是非洲大廈,長頸鹿。
Among thousands of wonderful creatures in the world's ,this may not come to your mind in a moment. However, it has a lot of surprising design.In Japanese, Korean and Taiwanese, it is called Unicorn! It is the African mansion, giraffe.

今年的野望自然國際影展中,其中一支影片「血」實的記錄了解剖長頸鹿的過程,藉由瞭解解剖構造,讓人們得以一窺這種珍奇巨獸的神奇之處。
In this year's World Vision International Film Festival, one of the films impressively records the process of dissecting the giraffe. By understanding the anatomical structure, people can glimpse the magic of this rare monster.

先簡單介紹一下,長頸鹿一般來說,身高約5米左右,其中脖子約占2米,長長的腿也有2米左右,其近親是長相類似斑馬和長頸鹿的混種,霍加狓。
First of all, giraffes are about 5 meters tall in general, including about 2 meters in the neck, and  2 meters in legs. Its close relatives are Okapi, which is similar to the mixture of zebra and giraffe.

長頸鹿最令人驚豔的,就是那長長的脖子了,在脖子的後方有一條強壯的韌帶,從頭一路連到背部,因此長頸路的背上有一個斜斜的隆起。這條韌帶的彈性與脖子的重量平衡時,長頸鹿的脖子會與地面成55度角,當要低頭喝水或吃葉子時,脖子前方的肌肉就會用力收縮,讓頭低下去,一旦肌肉放鬆,脖子就會在2秒之內從喝水的姿勢回到正常狀態,如此就能快速的逃離水邊。
The most stunning features  of giraffes is its long neck. In the back of the neck there is a strong ligament, all the way from the back to the back. That's why there is a ramp uplift on its back. The elasticity of the ligament and the weight of the neck balance, making  the giraffe's neck and the ground into a 55-degree angle, when giraffes want to bow to drink or eat leaves, the muscles in front of the neck will be forced to shrink, so that the head down.  The neck will be from the water drinking  posture back to normal state  within 2 seconds , so they can quickly escape.

長頸鹿除了有世界上最長的脖子以外,還是世界上血壓最高的物種,高達人類的三倍,透過這麼高的血壓,才能將血液送到非常高的頭部。但大家有沒有想過,如果血壓這麼高,那長頸鹿低頭的時候會不會因為血流直沖腦門而炸腦呢?在長頸鹿靠近頭部的地方有一處平常沒有使用的血管網,當低頭時,這個血管網的入口就會開啟,讓一部份的血液流入,這樣就不會有那麼多的血沖進腦袋造成「出血性中風」了。
Giraffes in addition to the world's longest neck, they are the world's highest blood pressure species. There blood pressure is  up to three times of the human. Through such a high blood pressure, they can  send blood to a very high head. But how about that if the blood pressure is so high,  the giraffes would destroy it's brain if they bow and the blood will go straight into the forehead and brain? In the giraffes' head, there's  a place where there is usually no use of the vascular network. When they bow, the entrance of the vascular network will open, so  the superflous blood can flow into that network. There will not be so much blood burst into the head and cause "Hemorrhagic stroke".

跟血液相關的問題還有另外一個,長頸鹿除了長長的脖子還有長長的腿,當血液流到底部時,到底要怎麼樣才能抗衡重力,避免血液淤積在靜脈中呢?答案是「緊身褲」,長頸鹿的腿的皮膚非常的緊實,會壓迫靜脈避免靜脈擴張使血液無法流回,許多長跑者會傳彈性緊身褲也是相同的原因,這樣能促進血液迴圈,讓血液正常流動。
There are other problems associating to the circulation. Giraffes has very  long legs, when the blood flow to the bottom of the leg. How can the blood counter the gravity and go back to heart, avoiding blood deposition in the vein ? The answer is "tight pants", the giraffe's legs have very tight skin, which will surppress the veins to avoid intravenous expansion of the vein.Thus, blood can now flow back. Many long-distance runners wear tight pants for the same reason, this can promote blood circulation, so they can perform better.

既然長脖子在帶給長頸鹿這麼多的麻煩的同時只有一些好處,可以吃到比較高的葉子,為什麼還是演化出來呢?有些人會說長脖子能夠早點看到掠食者從而避免傷亡,但這並不成立,長頸鹿被掠食者追逐的場景在非洲也是天天上演,如果有看過《自私的基因》這本書,也許就能理解,長脖子的基因讓攜帶者能夠在角逐交配權上帶來較大的優勢,因此有利於自己的散播,當其在物種中累積的越多,脖子自然就會往長的方向演化。


相對于龐大的身軀,長頸鹿的軀幹只占了小小一部份,不管是消化道還是心、肺都不能太大,因此,也各自演化出一套特殊的構造來適應環境。

在空間不大的情況下,長頸鹿的腸子非常長,但同時也非常的細,這樣的構造讓食物只能緩慢的通過,能夠完全吸收其中的養份及水份,在食物和水不多的非洲,這是很成功的演化。長頸鹿有四個胃,與牛相似,他也會不停的反芻,一天大概花12小時來咀嚼,這樣,細碎的葉渣才能進到細細的腸子。

肺臟影響了呼吸的能力,長頸鹿一口氣大約要吸進18公升,包括留在長長的氣管無法進入肺部的3公升氣體,一旦快速逃跑的時候,長頸鹿的腸子變會隨著前腳著地時往前推,後腳著地時往後,如此一前一後,就形成類似活塞的效果,讓肺臟能夠更快的進出氣,以滿足時速50公里的耗氧量,如此巧思,真令人訝異。


長頸鹿的心臟不大,但是心臟內的空間相對於心壁的厚度就與人類不同了。長頸鹿的心壁非常的厚,足足有8公分,大概是人類的45倍,這麼厚實的肌肉,當然能夠創造出強大的壓力、強大的輸送力,讓血流得以抵達頭部。


最後,來說說外觀上的巧思,長頸鹿的身上有許多的深色斑塊,也許看到這些,第一個想法就是這是保護色,讓掠食者比較不容易發現,但長頸鹿都那麼高那麼顯眼了,有這些有什麼用?其實這些斑塊真正的功能是散熱;深色散熱快,在這些斑塊邊緣的底下,有一圈血管,而這圈血管內交織著微血管,就像補夢網一樣,一旦長頸鹿需要散熱的時候,這些微血管內就會充滿血液,將體熱散發出去,透過紅外線攝影,就能看到藍底紅斑的長頸鹿呢!


大自然的設計如此巧妙,學習其設計之道,就是創新的另外一種道路。

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