（本文发表于2021年11月10日，作者为麦考瑞大学生物科学系博士后劳拉·瑞恩，弗林德斯大学副教授查理·胡维尼耶斯）

The presumed death of 57-year-old Paul Millachip in an apparently fatal shark bite incident near Perth on November 6 is a traumatising reminder that while shark bites are rare, they can have tragic consequences.

11月6日，57岁的保罗·米拉齐普在珀斯附近发生的一起显然很致命的鲨鱼咬人事件中被推定死亡，这是一次让人伤心的提醒，提醒人们虽然鲨鱼咬人的情况很罕见，但它们可能会带来悲剧性的后果。

Despite the understandably huge media attention these incidents generate, there has been little scientific insight into how and why they happen.
Sharks in general, and white sharks in particular, have long been described as “mindless killers” and “man-eaters”.
But our recent research confirms that some bites on humans may be the result of mistaken identity, whereby the sharks mistake humans for their natural prey based on visual similarities.

尽管这些事件引发了媒体的大量关注（这也可以理解），但是，关于这些事件是如何发生的以及为什么发生，相关的科学洞见却少之又少。
一般来说，鲨鱼，特别是大白鲨，长久以来都被描述为“盲目的杀手”和“食人生物”。
但我们最近的研究证实，有些咬人事件可能是误认身份的结果，即鲨鱼基于视觉上的相似性，把人误认为了它们的天然猎物。

Sharks have an impressive array of senses, but vision is thought to be particularly important for prey detection in white sharks. For example, they can attack seal-shaped decoys at the surface of the water even though these decoys lack other sensory cues such as scent.

鲨鱼拥有一系列令人印象深刻的感官，但视觉被认为是对大白鲨探测猎物尤为重要的感官。比如说，它们会攻击水面上海豹形状的诱饵，即使这些诱饵缺乏其他感官线索，比如说气味。

The visual world of a white shark varies substantially from that of our own. White sharks are likely colourblind and rely on brightness, essentially experiencing their world in shades of grey. Their eyesight is also much less acute than ours – in fact, it’s probably more akin to the blurry images a human would see underwater without a mask or goggles.

大白鲨的视觉世界与我们的大相径庭。大白鲨很可能是色盲，依靠的是亮度，基本上是以各种浓淡的灰色调在体验它们的世界。它们的视力也远不如我们敏锐，事实上，它们目力所见的很可能更接近人类在不戴面具或护目镜情况下在水下看到的模糊图像。

The mistaken identity theory

误认身份理论

Bites on surfers have often been explained by the fact that, seen from underneath, a paddling surfer looks a lot like a seal. But this presumed similarity has only previously been assessed based on human vision, using underwater photographs to compare their silhouettes.

冲浪者被咬，通常都会这样解释：从下往上看，划水的冲浪者看起来很像一头海豹。但这种假想中的相似性，之前都只是根据人类的视觉评估出来的，为了比较它们的暗色轮廓，用的是在水下拍摄的照片。

Recent developments in our understanding of sharks’ vision have now made it possible to examine the mistaken identity theory from the shark’s perspective, using a virtual system that generates “shark’s-eye” images.

最近，我们对鲨鱼视觉的理解有了新的进展，能使我们有可能从鲨鱼的视角来检验误认身份理论，我们用了一套虚拟系统来生成“鲨鱼眼”中的影像。
原创翻译：龙腾网 http://www.ltaaa.cn 转载请注明出处


In our study, published last month, we and our colleagues in Australia, South Africa and the United Kingdom compared video footage of seals and of humans swimming and paddling surfboards, to predict what a young white shark sees when looking up from below.

在我们上个月发表的研究中，我们和来自澳大利亚、南非和英国的同事们比较了海豹和人类游泳以及划冲浪板的视频片段，以此来预测一条年轻的大白鲨从水下往上看时能看到的东西。



（图解：鲨鱼视角中划水的冲浪者和海豹，表明大白鲨可能很难区分这两者）

We specifically studied juvenile white sharks – between of 2m and 2.5m in length – because data from New South Wales suggests they are more common in the surf zone and are disproportionately involved in bites on humans. This might be because juvenile sharks are more likely to make mistakes as they switch to hunting larger prey such as seals.

我们专门研究了青少年时期的大白鲨（长度在2米到2.5米之间），因为来自新南威尔士州的数据表明，这部分鲨鱼在冲浪区更常见，而且其在咬人事件中的占比高到不成比例。这可能是因为幼年鲨鱼在切换到捕食体型更大的猎物（如海豹）时，更容易犯错。

Our results showed it was impossible for the virtual visual system to distinguish swimming or paddling humans from seals. This suggests both activities pose a risk, and that the greater occurrence of bites on surfers might be lixed to the times and locations of when and where people surf.

我们的研究结果显示，想让这套虚拟视觉系统将游泳或划水的人类和海豹区分开来是不可能的。这就表明这两种活动都会带来风险，而冲浪者被咬发生得更多，可能与人们冲浪的次数、时间、地点有关。

Our analysis suggests the “mistaken identity” theory is indeed plausible, from a visual perspective at least. But sharks can also detect prey using other sensory systems, such as smell, sound, touch and detection of electrical fields.

我们的分析表明，至少从视觉角度来看，“误认身份”理论确实是可信的。但是鲨鱼也能用其他感官系统探测猎物，比如嗅觉、听觉、触觉和探测（生物）电场。

While it seems unlikely every bite on a human by a white shark is a case of mistaken identity, it is certainly a possibility in cases where the human is on the surface and the shark approaches from below.

虽然大白鲨每一次咬人貌似不太可能都是出于误认，但是，人在水面上而鲨鱼从下方接近的情况下，这毫无疑问是一种可能性。
原创翻译：龙腾网 http://www.ltaaa.cn 转载请注明出处


However, the mistaken identity theory cannot explain all shark bites and other factors, such as curiosity, hunger or aggression are likely to also explains some shark bites.

不过，误认身份理论无法解释所有的鲨鱼咬人事件，其他因素，比如好奇心、饥饿感或攻击性也许也能解释一部分鲨鱼咬人事件。



（图解：弗里曼特尔（珀斯）港附近的海滩在一起致命的鲨鱼咬人事件后被关闭）

Can this knowledge help protect us?

这部分知识能帮助我们保护自己吗？

As summer arrives and COVID restrictions lift, more Australians will head to the beach over the coming months, increasing the chances they might come into close proximity with a shark. Often, people may not even realise a shark is close by. But the past weekend gave us a reminder that shark encounters can also tragically result in serious injury or death.

随着夏天的到来以及新冠（出行）限制的撤销，在未来几个月内会有更多的澳大利亚人前往海滩，这也增高了他们与鲨鱼亲密接触的几率。通常情况下，人们甚至都意识不到鲨鱼就在附近。但是，上周末的事件提醒了我们，遭遇鲨鱼也可能会导致悲剧性的重伤或死亡。

Understanding why shark bites happen is a good first step towards helping reduce the risk. Our research has inspired the design of non-invasive, vision-based shark mitigation devices that are currently being tested, and which change the shape of the silhouette.

理解鲨鱼咬人事件的发生原因，是帮助降低风险的第一步。我们的研究为非侵入性且基于视觉的鲨患缓解装置的设计提供了灵感，该装置目前正在接受测试，它改变了暗色轮廓的形状。