这种企鹅在热带安家，七月底在楼顶又见到了ta

德国小镇斯特拉尔松德（Stralsund）有个海洋馆。这个海洋馆最著名的地方，在于它的楼顶：二十多米高的大露台上，吹着习习海风，坐看蓝天上云卷云舒，惬意极了。

露台上有一个不大的水池，里边堆着假山，假山的洞窝偶尔露出一只毛茸茸的白褐各半的脑袋。再仔细看看那脑袋，不禁让人大吃一惊，这竟然是一只企鹅？

The OZEANEUM in the northern German port city of Stralsund has a rather satisfying rooftop. Here you can enjoy the refreshing Baltic breeze, see the bright blue summer sky above and enjoy the historic Hanseatic town of Stralsund below.

And in the middle of the rooftop sits a rocky pool. Every now and then, a fluffy brown-and-white head pokes out from one of the artificial nesting caves.

A penguin.

这是夏天七月底，这块楼顶更是直接承受阳光照射。他们竟然能养自带燕尾服的企鹅？

什么企鹅这么耐热？

I had to look twice to trust my own eyes. It was late July and the rooftop was baking under direct sunshine that standing there in a T-shirt already made me feel warm enough. Yet these birds, commonly supposed to appear in below-ice temperature only, appeared perfectly comfortable.

Had someone forgotten to tell the penguins that they belong in Antarctica?

酷暑求生，企鹅脱掉燕尾服

答：洪堡企鹅。

这种企鹅原产地在南美洲西海岸，南纬5度到43度之间，秘鲁、智利都有分布。熟悉地理的同学们都知道，这个维度跨越了温带、亚热带甚至热带，但在1799年到1804年的美洲之旅中，德国科学家亚历山大·冯·洪堡（Alexander von Humboldt）居然发现这里有企鹅在活动，消息一经公布震惊了当时的整个学界。三十年后，德国博物学家弗兰茨·尤利乌斯·费迪南德·迈恩（Franz Julius Ferdinand Meyen）为这种物种正式命拉丁学名为（Spheniscus humboldti），日常就叫“洪堡企鹅”。

为适应不同的生存环境，洪堡企鹅和南极企鹅在身体条件上有很大不同。大家印象中的南极企鹅一般都是肚子白背部则为黑色或者深蓝色，很有利于吸收阳光的热量进行保暖。

但对生活在低纬度地区的洪堡企鹅，深色羽毛则不利于散热。相比南极企鹅，洪堡企鹅背部羽毛颜色更浅，也更加稀疏。如果说南极企鹅穿的是保温效果奇佳的蓝黑色毛料燕尾服，洪堡企鹅穿的就是浅色针织衫，散热效果要好很多。

I had always associated penguins with snow, sea ice and the Antarctic and I personally believe many people did it. But nature, as it often does, had another story to tell.

The Humboldt penguin is native to the coastal region ranging roughly from Peru to central Chile, or between about 5 and 43 degrees south latitude. As the digit shows, some of their colonies even live surprisingly close to the equator.

The species owes its name to the German explorer and naturalist Alexander von Humboldt, who observed these penguins during his famous expedition across Latin America between 1799 and 1804. His reports astonished European scientists of the time. Decades later, German zoologist Franz Julius Ferdinand Meyen formally described the species and named it Spheniscus humboldti in Humboldt's honor.

为了适应较高气温，洪堡企鹅的羽毛进一步演化得更短、更薄。它们的羽毛长的短小精干，一点都没有南极亲戚的厚重感。就这点又小又短的羽毛，洪堡企鹅还要每年换一换，而且是从头到脚的换，号称“毁灭性换羽”。它的脸、嘴等部位干脆不长毛，大片的粉红色皮肤裸露在外边，又萌又凉快。

一位朋友UrLunkwill贡献的图片，能清楚看到洪堡企鹅粉嘟嘟的小脸蛋。

脂肪具有保温作用，因此体型较胖的动物通常更耐寒。所以南极企鹅一般都是肉乎乎圆滚滚的，身上几乎找不到凹陷下去的地方，一层肥油把自己包的严严实实。洪堡企鹅反其道而行之，比南极的亲戚们瘦了不止一圈，耐热程度也就提高了不止一个档次。

They have even kept diet. Antarctic penguins resemble little walking barrels as thick layers of fat help conserve heat in water that can remain below freezing. In deep contrast, Humboldt penguins are noticeably slimmer, carrying less insulation and dissipating heat more efficiently.

人们可能会认为，洪堡企鹅的祖先可能从南极逐渐向北迁徙，并在长期演化中逐步适应了低纬度地区的高温环境。

不过，这一推测并不符合目前学界的主流观点。2017年的《自然·通讯》（Nature Communications）登出一篇论文，研究了在新西兰发现的约6000万年前的古代企鹅化石。现在学界的主流认知是，企鹅是在相对温暖的时代诞生于今天新西兰附近，后来随着洋流游到南极，在那里进化出了厚厚的羽毛和圆滚滚的体型，通过这些措施适应了极地的寒冷。

在企鹅诞生的那个时代，地球的平均温度比现在高好几度，南极甚至都还没有形成冰盖。这意味着，企鹅的演化路径与上述推测恰好相反：它们起源于相对温暖的地区，随后迁徙至南极，又遇上了全球温度降低，在以万年为计数的单位里长出了浓密的黑蓝色羽毛，吃的圆滚滚，变成了现在的模样。

为了生存而适应环境的桂冠，当由洪堡企鹅和南极企鹅共享。

自助者，天助之

企鹅的命运要靠自我奋斗，也要看气候的行程。毕竟南极均温在零下十几摄氏度甚至几十摄氏度，热带确实动辄三十多摄氏度，企鹅很难同时适应这两地的气温。

洪堡企鹅的存在，要感谢大自然的馈赠。洪堡在美洲科考的过程中，发现洪堡企鹅生活的地区平均海水温度通常在15-18摄氏度之间，气温低至4摄氏度高也就是30摄氏度，比一般的热带地区要低。再往地理学上考察，洪堡发现原来这里沿岸有一条寒流经过，降低了海水温度也顺便降低了气温。

Yet even all these adaptations cannot fully explain how a penguin manages to thrive so close to the tropics because the two environments are too strikingly contrast to each other.

The question was also answered by Humboldt. During his South American expedition, Humboldt noticed that coastal waters were unexpectedly cold despite their low latitude. Investigating further, he identified a vast current flowing northward from Antarctic waters along the Pacific coast.

Today it is known as the Humboldt Current, or the Peru Current. As its name shows, it cools both the sea and the air above it, creating a remarkably mild coastal climate near Peru. Sea surface temperatures often remain between 15 and 18 C, far cooler than one would expect at those latitudes.

洪堡寒流示意图。（图由AI生成）

洪堡发现的寒流后来被命名为洪堡寒流，也因为经过秘鲁等国沿岸海域而被称作秘鲁寒流。对洪堡企鹅来说，这条寒流是个不可取代的庇护所，夏天实在热到不行了，能一个猛子扎到凉爽的海水中，给自己降降温。更关键的是，寒流带来了丰富的食物，企鹅是爱吃肉的动物，其食谱包括鱼虾蟹螺，洪堡寒流带来了大量磷虾，这本来是南极才有的生物，现在却给热带的企鹅提供了美餐。

For Humboldt penguins, the current functions as a giant natural air conditioner that even people in Europe are dreaming of. Whenever the sun becomes too intense, they simply dive into cool seawater.

Even more importantly, the Humboldt current supports one of the richest marine ecosystems on Earth. Cold water rising from the deep carries abundant nutrients to the surface, triggering explosive growth of plankton, which in turn feeds enormous populations of fish, squid and krill.

这个发现也让洪堡达成了既命名企鹅又命名洋流的成就，纵观整个人类历史，这样的例子也不多见。再算上洪堡大学、洪堡基金会、洪堡论坛……感觉在德国，什么都能用洪堡命名。

柏林洪堡论坛门口

进一步把格局打开，我们会发现这世界上除了洪堡企鹅，还有这么几种企鹅生活在温带、热带、亚热带：

麦哲伦企鹅（Magellanic penguin）分布于阿根廷和智利南部，那里有福克兰寒流帮助降温；

非洲企鹅（African penguin）生活在南非和纳米比亚沿岸，受本格拉寒流（Benguela Current）影响，温度也可控；

加拉帕戈斯企鹅（Galápagos penguin）干脆生活在赤道附近的加拉帕戈斯岛，洪堡寒流和克伦威尔洋流在这里造出了一个不那么热的小小家园，让企鹅们能对抗一年好几个月的阳光直晒。

笔者这次造访的斯特拉尔松德也不例外。这个小镇位于德国波罗的海沿岸，是典型的的温带海洋性气候。感谢波罗的海给力的调节作用，这里虽然纬度跟中国的漠河差不多，却是冬无严寒、夏无酷暑，全年降水均匀，普通人在这里生活的十分惬意。洪堡企鹅也沾了这点光，过上了不冷不热的生活，企鹅馆常年布置在楼顶露天，和游客们一起欣赏这蓝天白云。

洪堡企鹅居住的屋顶全景

从屋顶往外看

这就是大自然的神奇之处。汹涌的大洋里有和陆地河流类似的洋流，终年不息地朝着一个方向流动，带动海洋里的本来渺小的生命随着它迁徙，旅程动辄跨越上万公里。海水的温度影响了沿岸，改变了原本酷热的环境，让小小的企鹅在亚热带甚至热带也有自己的立足之地。

Invisible to us, enormous currents circulate endlessly around the globe, transporting heat, nutrients and life across thousands of kilometers. A slight change in water temperature can reshape an entire coastline, allowing a bird that most of us associate with icebergs to flourish in subtropical South America — or on the roof of a museum in northern Germany.

再往大了想，地球或许也是这样。宇宙环境是普遍极端的，恒星温度高达数亿开尔文，缺少光照的空间温度则接近绝对零度，都是生命不敢想象的严酷。但就在银河系一个小小的角落里，多种因素共同造就了地球这么一颗小小的岩质行星，恰好离太阳不远不近有液态水，经过很多亿年的演变，终于被播撒上生命成了我们的家园。

从这个角度看，我们人类主动适应环境，常年不断进化，全球各纬度都能生存，也和洪堡企鹅一样，都是奇迹般的存在。

Sometimes, standing beside a penguin pool, you end up learning more about the planet than about the penguins themselves. The Earth, a rocky planet with so accurately proper distance to the sun that liquid water can exist on it and breed life for 3.8 billion years, is also in a small and subtle corner of the Universe where the natural forces accidentally make good.

Perhaps that is what Humboldt as a science teacher would have appreciated.

记者：张周项

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