科学美国人60秒 SSS 鲨鱼（在线收听）

Sharks aren't typically thought of as vegetarians. Or even omnivores. But about 10 years ago, scientists documented a dainty relative of the hammerhead shark, known as a bonnethead shark, consuming copious 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 crabs and squid and other little invertebrates 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 analyzed 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 gut, they are definitely acting like omnivores. So there's probably something going on, on probably a microbial level, that's helping them break down this seagrass."The full nutrition info is in the Proceedings 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 coastal ecosystem 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 stabilizing role in food web dynamics. They're not a top apex predator. And they're probably playing a large role in nutrient transport in those seagrass meadow ecosystems 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。”