谜团解开：圣诞岛红蟹迁徙的能量来源

Crab Swarm

蟹群

Photograph courtesy Mrinalini, Bangor University

照片来源：Mrinalini/班戈大学（Bangor University）

Migrating Christmas Island red crabs congregate on a beach in the Australian territory of Christmas Island (map) in an undated picture.

在澳大利亚的属地圣诞岛（Christmas Island）上，迁徙的红蟹聚集在海滩上。

A new study solves a longstanding mystery surrounding the crabs: how the the normally sedentary species has the stamina to "undergo one of the most arduous migrations on Earth," in the words of study co-author Lucy Turner.

最近，一项最新的研究解决了一个由来已久的红蟹之谜，之前科学家们一直搞不清楚这种习惯定居的物种哪来的体力去“承受地球上最费力的迁徙活动”。

When the wet season blows into Christmas Island (map) each year, millions of Christmas Island red crabs hike for several days, from a high rain forest plateau down to Indian Ocean beaches, where the crabs mate in burrows.

每年当圣诞岛迎来雨季时，数百万只圣诞岛红蟹就会展开数天的大迁徙，它们从较高的雨林高原向印度洋的海滩进发，在海滩边上挖好洞以后就开始交配。

"It's an amazing feat—going from not being able to exercise for more than ten minutes to walking for several miles," said Turner, a biologist at the University of Bristol in the United Kingdom.

“这绝对是惊人的壮举。一般情况下，它们只会一动不动的呆上十几分钟，而现在它们又要展开好几公里的长途跋涉，”英国布里斯托大学的生物学家露西·特纳说，她同时也是主导红蟹研究的副研究员。

But by sampling circulatory fluid—the equivalent of blood—from migrating crabs, Turner and colleagues discovered that a surge in the crustacean hyperglycemic hormone works with glucose, an energy-producing sugar, to fuel the epic trek.

通过对迁徙红蟹的体液进行取样，特纳和她的同事们发现红蟹体内的甲壳动物高血糖激素（crustacean hyperglycemic hormone）激增，在这种激素的作用下，葡萄糖开始发挥作用，为长途跋涉提供能量支持。

The crab's endocrine system also stockpiles enough sugar to allow the crabs to return to their forest homes, Turner added.

特纳补充说，红蟹的内分泌系统也储备了足够多的糖分，足以支撑它们返回位于雨林的老家。

Study published in the September issue of the Journal of Experimental Biology.

这项研究成果将刊登在九月份的《实验生物学杂志》（Journal of Experimental Biology）上。

—Christine Dell'Amore

——克莉丝汀·戴尔艾穆尔（Christine Dell'Amore）

Published September 3, 2010

2010年9月3日

Invasion of the Crabs

红蟹入侵

Photograph from Photolibrary

照片来源：Photolibrary

Children watch migrating Christmas Island crabs (file photo), which overtake Australia's Christmas Island at the beginning of the wet season, in October or November.

孩子们正在观察迁徙的圣诞岛红蟹，雨季一般是从十月或十一月开始，届时红蟹将遍布整个圣诞岛。

The crab march "completely disrupts most people's daily lives," even shutting down major roads, study co-author Turner said. But Christmas Islanders have "learned to live with it."

“红蟹大军完全扰乱了大多数人的日常生活，甚至连主要的公路也关闭了，”特纳说。“但岛民们已经学会了如何和它们相处。”

Some residents are also "quite protective" of the 8-inch-long (20-centimeter-long) crustaceans--schoolchildren put up signs encouraging people to drive carefully, she said.

有些居民对这种20厘米长的甲壳类动物相当有保护意识——小学生们会在道路上设置标语，号召人们小心驾驶，以免伤到红蟹。

"Having said that, there are so many crabs, some get squashed."

“即便如此，还是有很多红蟹会被压扁。”特纳说。

Published September 3, 2010

2010年9月3日

Crab Swarm Spawns by the Sea

海边产卵的蟹群

Photograph from Photolibrary

照片来源：Photolibrary

Once Christmas Island crabs arrive at their beachside mating spots, males dig burrows and defend them from marauders, study co-author Turner said (file photo).

圣诞岛红蟹一旦到达海边的交配地点时，雄性就会挖洞以抵御掠食者。

A female mates in a male's burrow, then makes a beeline for the ocean. Her eggs hatch almost immediately after contact with the seawater, Turner said.

雌蟹会在洞里和雄性交配，交配完成以后会径直爬向大海，它的卵会在接触海水的瞬间孵化。

The baby crabs develop in coastal sea grasses, eventually coming onto land to repeat the life cycle.

幼蟹会在沿海的海草中慢慢长大，最后爬上陆地重复这种生命循环。

Published September 3, 2010

2010年9月3日

Playing Through

凑热闹

Photograph by Roger Garwood, National Geographic

照片来源：Roger Garwood/国家地理

Golfers, including these 1980s players, on Christmas Island have learned to cope with the annual crab invasion, Turner noted.

甚至这些80后的高尔夫选手都知道该如何应付这种一年一度的红蟹入侵。

"There's a special rule for golf courses: If the crab knocks the ball one way, you have to go with it," she said.

“这里的高尔夫课程中有一条不成文的规定：不管红蟹将球碰到何处，你都要在这个地方击球，”特纳说。

Fortunately, Christmas Island crabs aren't just a nuisance. Their feces acts as a crucial forest fertilizer, and their burrowing turns and aerates the soil, according to the Christmas Island National Park website.

幸运的是，圣诞岛红蟹带来的也不全是麻烦，据圣诞岛国家公园网站介绍，它们的排泄物是重要的雨林肥料，它们挖的洞还会松动土壤。

Published September 3, 2010

2010年9月3日

Crab Standoff

僵持的一对红蟹

Photograph courtesy Mrinalini, Bangor University

照片来源：Mrinalini/班戈大学

During their 2007 fieldwork, Turner and colleagues had to deal with curious crabs (above, two Christmas Island red crabs in an undated picture).

2007年野外考察的时候，特纳她的同事们经常要和这种古怪蟹类打交道。

The zealous climbers got into the research station and even the scientists' houses. "If you leave the door open, you're probably going to find one in there," she said.

这些热情的攀爬者们不断涌入研究所内，甚至爬到科学家们的卧室内。“如果你出门的时候忘了关门，它们就会爬得到处都是，”特纳说。

The same went for the basketball-size coconut crab (see picture), the world's biggest land crab, of which Christmas Island has the world's largest population.

篮球大小的椰子蟹（coconut crab）也是科学家们研究的对象，椰子蟹是世界上最大的陆地蟹类，圣诞岛上的椰子蟹数量是世界上最多的。

Published September 3, 2010

2010年9月3日

Beach Trip

海滩之旅

Photograph from Photolibrary

照片来源：Photolibrary

Of Christmas Island's 14 crab species, the Christmas Island red crab (above, crabs migrating in an undated picture) is the most easily spotted, according to the Christmas Island National Park website.

据圣诞岛国家公园网站介绍，作为圣诞岛上的14种蟹类之一，圣诞岛红蟹是最为常见的。

The crabs burrow in a variety of habitats, including coastal terraces, dense rain forests, and even domestic gardens, according to the website.

红蟹会在各式各样的栖息地中挖洞，海岸阶地，浓密的雨林，甚至家庭花园中都能发现它们的踪迹。

During the dry season, a crab will plug its burrow entrance with leaves to keep the space humid—and disappear for up to two or three months.

在干旱季节的时候，红蟹会用树叶塞住洞口，保持洞穴里的湿润——然后就一连两三个月躲在地底下。

Published September 3, 2010

2010年9月3日

Crabby Tourist

山高路远

Photograph by Roger Garwood, National Geographic

照片来源：Roger Garwood/国家地理

For the best crab viewing, Australian officials advise tourists (pictured, a Christmas Island visitor in an undated photo) to arrive during the last quarter of the moon in either November or December.

每年十一月或十二月的下弦月是最佳的观蟹时机，澳大利亚官方建议游客们选择这个时间前来圣诞岛观光。

The crabs breed on a strict timetable: Unwaveringly, females spawn before sunrise during the last quarter of the moon, according to the Christmas Island National Park website.

圣诞岛国家公园网站介绍说，红蟹的繁殖遵循严格的时间表：雌蟹只有在下弦月时的日出之前才会产卵。

Published September 3, 2010

2010年9月3日

On Track for Disaster

大难临头

Photograph by Roger Garwood, National Geographic

照片来源：Roger Garwood/国家地理

Of the hazards the migrating crabs encounter, human infrastructure is the greatest (file photo).

人造基础设施对迁徙的红蟹构成了巨大的威胁。

Christmas Island has erected some "crab crossings": walls or plastic fencing along roads that detour the crab swarms away from traffic, according to the Christmas Island National Park website.

据圣诞岛国家公园网站介绍，圣诞岛上建立了一些“红蟹斑马线”：通过沿路设立围墙或塑料围栏让蟹群避开交通。

Published September 3, 2010

2010年9月3日

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