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Studies suggest how the snake coils matters more than muscle size
諸多研究暗示了，該種蛇如何比肌肉大小更能捲曲盤繞物體。
It’s not the size of a snake’s muscles that matter, but how it uses them. King snakes can defeat larger snakes in a wrestling match to the death because of how they coil around their prey, researchers report March 15 in the Journal of Experimental Biology.
在2017年3月15日的《實驗生物學期刊》中，研究人員們記述，問題不是蛇的肌肉大小，而是蛇如何使用肌肉。在搏鬥賽中，由於王蛇捲曲盤繞其獵物的方式，王蛇能鬥死較大的蛇。
King snakes wrap around their food and squeeze with about twice as much pressure as rat snakes do, says David Penning, a functional morphologist at Missouri Southern State University in Joplin. Penning, along with colleague Brad Moon at the University of Louisiana at Lafayette, measured the constriction capabilities of almost 200 snakes. “King snakes are just little brutes,” Penning says.
美國密蘇里州南方州立大學(位於密蘇里州喬普林市)的功能形態學家David Penning表示，王蛇纏繞其食物，並使用約兩倍於鼠蛇的壓力緊縮。Penning連同路易斯安那大學的同僚Brad Moon，測量了將近200種蛇的緊縮能力。Penning宣稱：「王蛇只是小野獸。」
King snakes, which are common in North American forests and grasslands, are constrictor snakes that “wrestle for a living,” Penning says. They mainly eat rodents, birds and eggs, squeezing so hard, they can stop their prey’s heart (SN: 8/22/15, p. 4). In addition, about a quarter of the king snake diet is other snakes.
Penning表示，於北美森林及草原常見的王蛇，是為生存搏鬥之將獵物勒緊致死的蛇。牠們主要進食齧齒動物、鳥類及蛋，緊縮得很牢固，牠們能使獵物心臟停止跳動。另外，王蛇的食物約1/4是其他蛇類。
King snakes can easily attack and eat vipers because they’re immune to the venom, but when they take on larger constrictors, such as rat snakes, it has been unclear what gives them the edge. “That’s not how nature goes,” Penning says, because predators are usually larger than their prey.
王蛇能輕易攻擊並吃食蝰蛇(響尾蛇科的毒蛇)，因為牠們對於毒液具有免疫力。不過，當牠們挑戰諸如鼠蛇等，將獵物勒緊致死的較大蛇類時，什麼賦予牠們此優勢，一直不詳。Penning宣稱：「那不是大自然運作方式，因為獵食者通常比獵物大。」
King snakes, though, can eat snakes up to 35 percent larger than themselves. One of the largest king snake conquests on record, from 1893, is of a 5-foot-3-inch rat snake, about 17 percent larger than the 4-foot-6-inch king snake that consumed it, Penning says.
Penning表示，雖然王蛇能吃食比自身大高達35%的蛇。不過從1893年以來，王蛇擊敗的最大記錄之一，是5英尺3英吋的鼠蛇，大約比吃食牠的王蛇大17%。
“David Penning is really one of the first researchers that has been looking at the anatomy, physiology and function of these snakes” to understand how king snakes are superior to rat snakes, says Anthony Herrel, a functional morphologist and evolutionary biologist at the French National Museum of Natural History in Paris.
功能形態學家兼法國國家自然史博物館(位於巴黎)的演化生物學家，Anthony Herrel宣稱：「實際上，David Penning是一直探究此些蛇類構造、生理及功能，來瞭解為何王蛇優於鼠蛇的最早研究人員之一。」
To determine what makes these snakes kings, Penning and Moon compared their muscle size, ability to escape attack and the strength of their squeeze to that of rat snakes. In one test, the researchers shook dead rodents enticingly in front of the snakes to goad them into striking and squeezing. Sensors on the rodents recorded the pressure of the squeeze.
為了斷言什麼使此些蛇成為最猛者，Penning及Moon比較了牠們的肌肉大小、避開攻擊的能力及緊縮鼠蛇的力量。在一項測試中，此些研究人員在這些蛇的前面，誘惑性搖晃死的齧齒動物，來刺激牠們進行攻擊及緊縮。於齧齒動物身上的偵測器記錄了緊縮壓力。
The king snakes constricted with an average pressure of about 20 kilopascals, stronger than the pumping pressure of a human heart. Rat snakes in the same tests applied only about 10 kilopascals of pressure.
此些王蛇以平均大約20千帕斯卡(壓強單位，1帕斯卡=1牛頓/米2)緊縮，這比人類心臟的泵送壓力更強有力。在相同的測試中，鼠蛇僅施予大約10千帕斯卡的壓力。
But the king snakes weren’t bigger body builders. Controlling for body size, the two kinds of snakes “had the exact same quantity of muscle,” Penning says.
不過，王蛇並非較大的健美動物。Penning表示，就身軀尺寸的控制而言，這兩種蛇“具有恰好等量的肌肉”。
The snakes’ more powerful constriction is probably due to how they use their muscles, not how much muscle they have, the researchers conclude. They observed that the majority of king snakes in the study wrapped around their food like a spring in what Penning calls the “curly fry pattern.” Rat snakes didn’t always coil in the same way and often ended up looking like a “weird pile of spaghetti,” he says.
此些研究人員斷言，王蛇較強有力的緊縮可能起因於，王蛇使用其肌肉的方式，而不是有多少肌肉。他們觀察到，研究中的大多數王蛇，以Penning稱之為 “捲曲的油炸食物模式”，像彈簧般纏繞其食物。他表示，鼠蛇並非經常以相同方式捲曲纏繞，而往往最後看起來像“怪異的義大利麵堆”。
圖1. 王蛇的緊縮方式 (圖援用自原文)
圖2. 鼠蛇的緊縮方式 (圖援用自原文)
原文網址：https://www.sciencenews.org/article/king-snakes-strength-its-squeeze
翻譯：許東榮
本文來自: http://mypaper.pchome.com.tw/peregrine/post/1370480594光盈天然水贈品水光盈發財水礦泉水Logo高雄瓶裝水贈品水包裝飲水礦泉水Logo
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