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Sharks aren't typically thought of as vegetarians¹. Or even omnivores. But about 10 years ago, scientists documented a dainty relative of the hammerhead shark, known as a bonnethead shark, consuming copious² amounts of seagrass.

锤头鲨通常不被认为是素食主义者。甚至是杂食动物。但大约10年前，科学家记录了锤头鲨(又称bonnethead shark)的一种精致的近亲，它消耗了大量的海草。

"A lot of people kind of just thought they were consuming it incidentally, after going after crabs³ and squid and other little invertebrates⁴ that live in the seagrass meadows." Samantha Leigh, a PhD candidate at the University of California, Irvine. "So everyone thought they were kind of just passing it through their system and not really getting anything from it."

“很多人都认为他们只是顺便吃了它，在追赶螃蟹、乌贼和其他生活在海草草原上的无脊椎动物之后。”萨曼莎·利(Samantha Leigh)是加州大学欧文分校(University of California, Irvine)的博士生。“所以每个人都认为他们只是在通过他们的系统传递信息，并没有从中得到任何东西。”

So Leigh and her colleagues hauled five of the small sharks back to a Florida lab, and put them on a three-week diet: 90 percent seagrass, 10 percent squid. And analyzed⁵ the digestibility of that diet. Turns out, the sharks actually put on pounds, and were able to digest the seagrass just as well as young green sea turtles do.

于是，利和她的同事们把5条小鲨鱼带回了佛罗里达的实验室，让它们吃上三周的食物:90%的海草，10%的乌贼。并分析了其消化率。事实证明，鲨鱼的体重实际上增加了，它们能像年轻的绿海龟那样消化海草。

"It seems like even though the bonnethead shark has what scientists would deem a carnivorous gut⁶, they are definitely acting⁷ like omnivores. So there's probably something going on, on probably a microbial level, that's helping⁸ them break down this seagrass."The full nutrition info is in the Proceedings⁹ of the Royal Society B.

“看起来，尽管锤头鲨拥有科学家认为的食肉肠道，但它们的行为确实像杂食动物。”所以可能有某种东西，在微生物水平上，帮助它们分解海草。营养信息刊登在《英国皇家学会学报B》上.

The study also gives coastal¹⁰ ecosystem¹¹ managers something new to chew on: these sharks are like lawnmowers, trimming the seagrass, digesting it, and, yes, recycling it. "So they likely play more of a stabilizing¹² role in food web dynamics¹³. They're not a top apex¹⁴ predator¹⁵. And they're probably playing a large role in nutrient¹⁶ transport in those seagrass meadow ecosystems¹⁷ as well." As for whether we might convince more sharks to have a side salad with dinner? "I don't know that we'll be able to do that anytime soon."

这项研究也给了海岸生态系统管理者一些新的东西去咀嚼:这些鲨鱼就像割草机，修剪海草，消化，是的，循环利用。因此，它们可能在食物网络的动态中扮演更稳定的角色。它们不是顶级掠食者。它们也可能在海草草甸生态系统的营养运输中扮演着重要的角色。至于我们是否可以说服更多的鲨鱼在晚餐时吃副沙拉呢?“我不知道我们很快就能做到。”