Scorpions go terminator mode and reinforce their weapons with metal
Scorpions go terminator mode and reinforce their weapons with metal
蝎子开启“终结者”模式：用金属强化武器
Scorpions are armed with dual front pincers (technically known as chelae or pedipalp appendages) and a venom-injecting telson, or stinger, on the posterior of their tail. These things look dangerous enough on their own, but a chemical examination showed they contain metals like zinc, manganese, and iron. 蝎子配备有一对前螯（专业术语称为螯肢或触肢）以及位于尾部末端的毒液注射器，即尾刺。这些器官本身看起来已经足够危险，但化学检测显示，它们内部含有锌、锰和铁等金属。
“That the metals are there has been known since the 1990s,” said Sam Campbell, a biologist at the University of Queensland, Australia. “What we didn’t know was whether scorpions evolved to be like that or if it was accidental and they were just picking the metals up from the environment.” “早在20世纪90年代，人们就已经知道这些金属的存在了，”澳大利亚昆士兰大学的生物学家萨姆·坎贝尔（Sam Campbell）说，“但我们不清楚的是，这是蝎子进化出的特性，还是仅仅因为它们从环境中偶然摄取了这些金属。”
To answer this question, Campbell and his colleagues examined how metals are distributed across the stingers and pincers of different scorpion species. Based on their data, detailed in a recent study published in the Journal of The Royal Society Interface, there was nothing accidental about it. 为了回答这个问题，坎贝尔和他的同事们研究了金属在不同蝎子物种的尾刺和螯肢上的分布情况。根据发表在《英国皇家学会界面杂志》（Journal of The Royal Society Interface）上的一项最新研究，这些金属的分布绝非偶然。
Mapping the weapons
武器测绘
Campbell’s team focused on 18 scorpion taxa selected from a large collection at the Smithsonian National Museum of Natural History. To map the molecular structure of the scorpions’ weaponry, the researchers used high-resolution scanning electron microscopy coupled with micro-X-ray fluorescence imaging. 坎贝尔的团队从史密森尼国家自然历史博物馆的大量馆藏中挑选了18个蝎子分类群进行研究。为了绘制蝎子武器的分子结构图，研究人员使用了高分辨率扫描电子显微镜结合微区X射线荧光成像技术。
These methods allowed them to build color-coded maps of all the stingers and pincers, with individual metals localized in extremely high detail. Based on these maps, the team could reconstruct metal enrichment patterns within the weapons. 这些方法使他们能够构建出所有尾刺和螯肢的彩色编码图，并将各种金属的分布位置精确到极高细节。基于这些图谱，研究团队得以重构武器内部的金属富集模式。
In most of the studied specimens, zinc was highly concentrated at the extreme tip of the aculeus, the needle-like envenoming structure. “Zinc has all to do with hardness and ensuring that we retain the strength of the tip of the stinger,” Campbell explained. 在大多数研究样本中，锌高度集中在毒针（aculeus，即针状的排毒结构）的最尖端。“锌的作用完全是为了硬度，确保尾刺尖端保持强度，”坎贝尔解释道。
Just below this zinc-fortified tip, manganese often became the dominant metal in a distinct region lower in the aculeus. The purpose of manganese in the region below the aculeus, the team speculates, is probably to improve the flexibility and absorption of vibrations. 在这一锌强化尖端的下方，锰往往成为毒针下部特定区域的主要金属。研究团队推测，锰在毒针下方的作用可能是为了提高灵活性和减震能力。
Having both metals arranged in this way turns the stinger into a biological spear capable of punching through tough hides or exoskeletons of prey. “It makes sense because a scorpion’s sting is quite aggressive and produces quite a lot of force, so the stinger has to take it without snapping,” Campbell said. 将这两种金属以这种方式排列，使尾刺变成了一支能够刺穿猎物坚韧皮层或外骨骼的生物长矛。“这很有道理，因为蝎子的蛰刺动作非常猛烈，会产生很大的作用力，所以尾刺必须在承受这种力量的同时不发生断裂，”坎贝尔说。
The team noticed a similarly clever metal arrangement in the pincers. Zinc and iron enrichment was present only in the granular rows of the chela, specifically in the jagged, tooth-like bumps called denticles on the movable outer segment. The layout resembled a samurai sword, where the hardest material is concentrated mainly along the cutting edge. 研究团队在蝎螯中也发现了类似的巧妙金属排列。锌和铁的富集仅存在于螯肢的颗粒行中，具体来说，是在可活动外侧节上那些被称为“齿突”（denticles）的锯齿状凸起上。这种布局类似于武士刀，最坚硬的材料主要集中在刀刃上。
“When these denticles, these teeth pop up, we see the enrichment and then, in the entire area around them, all the rest of the claw, there is no metal whatsoever,” Campbell said. “当这些齿突出现时，我们能看到金属富集，而在它们周围的整个区域，即螯肢的其他部分，则完全没有金属，”坎贝尔说。
But when Campbell and his colleagues took a deeper dive into species-to-species variations in the scorpions’ weaponry design, they encountered yet another layer of complexity. “One of the things that made me want to do this investigation is that scorpions are all very different,” Campbell said. “They have different sizes and shapes of their pincers and their stingers, and there are significant differences in their behavior.” 但当坎贝尔和他的同事深入研究不同物种间蝎子武器设计的差异时，他们遇到了另一层复杂性。“促使我进行这项调查的原因之一是蝎子之间差异巨大，”坎贝尔说，“它们的螯肢和尾刺大小形状各异，行为上也存在显著差异。”
The team wanted to learn whether these differences are reflected in scorpions’ patterns of metal enrichment in their weaponry. It turned out they are. 研究团队想了解这些差异是否反映在蝎子武器的金属富集模式中。结果证明确实如此。
Metal allocation
金属分配
Scorpion species use their pincers and stingers in different ways. Species in the Buthidae family use their stingers for hunting prey and usually have long and slender pincers with relatively weak crushing power. On the other hand, adults of the Pandinus imperator species, known as the Emperor Scorpion, use the stingers only for self-defense and rely on their robust, massive claws to subdue and crush insects, young mice, and small lizards they feed on. 不同蝎子物种使用螯肢和尾刺的方式各不相同。钳蝎科（Buthidae）物种利用尾刺捕猎，通常拥有细长的螯肢，挤压力相对较弱。另一方面，被称为“帝王蝎”的成年个体则仅将尾刺用于自卫，并依靠其强壮巨大的螯肢来制服和压碎它们捕食的昆虫、幼鼠和小蜥蜴。
Going into the study, the team hypothesized that pincers built for generating high crushing force would contain the highest levels of metal to provide maximum hardness, while enrichment in the weaker, slender pincers would be lower. While this held true for zinc, the correlation was the exact opposite for iron. 在研究之初，团队假设为产生高挤压力而进化的螯肢会含有最高水平的金属以提供最大硬度，而较弱、细长的螯肢中金属富集程度会较低。虽然这一假设对锌成立，但对于铁来说，相关性却恰恰相反。
“The reason we suspect this is the case is that, rather than providing hardness to the claw, the iron enrichment has more to do with abrasion resistance,” Campbell said. “我们怀疑原因在于，铁的富集更多是与耐磨性有关，而不是为了给螯肢提供硬度，”坎贝尔说。
When a scorpion with large beefy pincers hunts, it can usually just crush its victim outright. Scorpions with long, slender claws need to hold onto a wrestling, fighting prey for longer to give the venom from their stings time to start working. As for zinc, the enrichment in the chelae was greater in species with reduced crushing power, most likely to compensate for their morphological weakness. 当拥有强壮大螯的蝎子捕猎时，通常可以直接压碎猎物。而拥有细长螯肢的蝎子则需要更长时间地抓住挣扎的猎物，以便让尾刺注入的毒液发挥作用。至于锌，在挤压力较弱的物种中，螯肢内的锌富集程度更高，这很可能是为了弥补它们形态上的弱点。
Another finding of the study was the inverse correlation between zinc uptake in the stinger and the claws. If a scorpion species has highly zinc-enriched pincers, its stinger is relatively zinc-poor, and vice versa. “It’s not that they just choose to reinforce one weapon over the other,” Campbell said. “I think this is an evolutionary drive toward reinforcing the weapon that is used the most.” 该研究的另一个发现是尾刺和螯肢中锌摄取量之间的负相关关系。如果某种蝎子的螯肢锌富集度很高，其尾刺的锌含量就相对较低，反之亦然。“这并不是说它们只是选择强化其中一种武器，”坎贝尔说，“我认为这是一种进化驱动力，旨在强化使用频率最高的武器。”
Still, there are some weapon design problems that evolution failed to solve and questions we have not yet answered. “One of the really interesting things that you see in scorpions in the wild is that their stingers can actually snap,” Campbell said. 尽管如此，仍有一些进化未能解决的武器设计问题，以及我们尚未回答的疑问。“在野外观察蝎子时，一个非常有趣的现象是它们的尾刺确实会断裂，”坎贝尔说。
Design trade-offs
设计权衡
The point at which the stingers usually snap, the researchers say, is at the zone where zinc enrichment at the tip abruptly stops and transitions into manganese. “It’s quite an interesting weakness for them to have in that region, and I don’t have a real theory or answer to why it is so,” Campbell said. 研究人员表示，尾刺通常断裂的位置，正是尖端的锌富集突然停止并过渡到锰的区域。“在那个区域存在这种弱点非常有趣，我还没有关于为什么会这样的确切理论或答案，”坎贝尔说。
One idea the team floats is that zinc and manganese are limited resources, so scorpions can only reinforce the most critical parts. 团队提出的一个观点是，锌和锰是有限的资源，因此蝎子只能强化最关键的部位。