十種生物的奇特繁殖方式(下)

Pregnancy

5.雄性生育的海馬

Most of us have mercifully forgotten the plot to the 1994 Schwarzenegger/DeVito vehicle "Junior." For the purposes of scientific edification, this article will do you the disservice of reminding you that it involves the future governor of California becoming pregnant. Hilarity ensues.

很多人已經大條地忘記了施瓦辛格和德維託主演的電影《威龍二世》中的故事情節。本着科普的目的，本文不怕死地提醒你這部電影講述的是未來的加利福尼亞州州長懷孕的故事。男性懷孕？很好玩吧，接下來的內容更有趣。

Absurd concept, of course, but show this comedic gem to a seahorse, and it would shrug its shoulders (if it had them). And that's not because the film received a 32 percent rating on the Rotten Tomatoes review site, but rather because there's nothing surprising about pregnant males in the seahorse world. When seahorses get around to reproducing, the males and females engage in an elaborate, lengthy and apparently beautiful courtship dance in which they entwine their tails and swim in tandem. Eventually, with their movements fully synchronized, the female slips a couple thousand eggs into a little pouch the male has just for that purpose. The male fertilizes the eggs and carries them around in his pouch where they hatch. He carefully tends to their needs as they grow, and when they're ready to head off into the world he actually has muscular contractions to push them out. Meanwhile, the female has been getting some more eggs ready. Time to tango again! A male seahorse can give birth in the morning and be pregnant again by evening.

男性懷孕顯然是一個腦洞大開的念頭，但要是把這部喜劇片給海馬看，他們最多無謂地聳聳肩。倒不是因爲這部電影在爛番茄影評網的好評率只有32%，而是因爲在海馬界，雄性妊娠真的沒什麼可奇怪的。當海馬們春心萌動想要繁衍後代時，雄海馬和雌海馬就會共舞一曲精緻、悠長又美妙的求愛舞，他們的尾巴纏繞在一起，成雙結對游來游去。待他們的舞步完全同步後，雌海馬便會將兩千個卵細胞滑入雄海馬妊娠專用的育兒袋中。雄海馬給這些卵細胞受精，並一直將受精卵放在體內用於孵化小海馬的育兒袋中。他會悉心照料這些受精卵，盡力滿足它們不同成長階段的需求。當小海馬們做好獨自面對世界的準備時時，雄海馬就會收縮育兒袋的肌肉，“生”出它們。與此同時，雌海馬一直在爲下次排卵做準備。又到了探戈時間！雄海馬竟然可以上午“生”孩子，晚上就再次懷孕。

ession

4.鳩佔鵲巢的藤壺

And now for some creepy parasitic procreation! When it comes to parasites, it's hard to choose from the array of weird, brilliant and often really troubling modes of self-replication. However, a lowly barnacle called rhizocephalans has a strategy so Machiavellian it deserves some attention here.

現在讓我們來看看寄生蟲們可怕的繁衍方式。說到寄生蟲，它們繁衍方式往往十分怪異，令人毛骨悚然還印象深刻。要從中挑選出更有特色的，還真的不容易。但是，一種不起眼的根頭目甲殼動物藤壺，爲了繁衍加不擇手段，因而值得我們的關注。

Rhizocephalans — we'll call it rhizo for short — doesn't look like your ordinary barnacle. As a young larva, rhizo floats around in hopes of encountering a passing crab. Given the size of the ocean, the chances are slim, but rhizos are produced in vast quantities, so a few are bound to find their targets. Once a rhizo makes crab-fall, it latches on, develops a little syringelike appendage and injects its cells into the crab's system. The rhizo cells find their way to their host's sinus and there begin to grow a root system that spreads everywhere, eventually poking out in exactly the spot where a female crab would carry its eggs. The parasite then lays its own eggs there in a little sac. For reasons not yet fully understood, if the crab happens to be a male it will actually change shape, widening its abdomen to more closely resemble a female. Also unknown is how exactly the rhizo convinces its host that the parasitic eggs it's carrying around are actually crab eggs. Then, as though in a scene from "Being John Malkovich," the parasite directs its host out to deeper waters where it can avoid predators and competition for food. It's all a bit unsettling. But is it as disturbing as Hymenoepimecis argyraphaga? Read on to compare.

根頭目甲殼動物藤壺，簡稱藤壺，與我們常見的藤壺在外觀上並不相同。它們的幼蟲在海面漂浮着，伺機遇到路過的螃蟹。大海茫茫，機會渺茫，但藤壺數量巨多，總有一些幼蟲能找到它們的目標。藤壺一旦發現蟹羣，就會立刻黏附在螃蟹身上，伸出像注射器的觸手，把它的細胞注入螃蟹體內。藤壺細胞會聚集在螃蟹的竇道中，然後開始生根增長，到處擴散，最後在雌蟹的卵巢中探出頭來，在螃蟹小小的腹部裏產卵。如果藤壺寄居的恰巧是雄蟹，它們就會把雄蟹的腹部擴寬到跟雌蟹差不多大，而藤壺爲什麼這樣做，人們也還沒搞清楚。那麼藤壺到底是怎麼讓螃蟹把它們的卵當成是自己的卵呢？人們也尚未得知。接着，就像電影《傀儡人生》中的情節一樣，藤壺會操縱它的宿主去深水區孵卵，以躲避天敵捕食和減少食物競爭。這聽起來真讓人毛骨悚然。但這和寄生黃蜂的繁殖方式相比，簡直小巫見大巫。不信就接着往下看吧！

erous Birth

3.謀“巢”害命的寄生蜂

Hymenoepimecis argyraphaga is a parasitic wasp that makes its home in lovely Costa Rica. When in the mood to reproduce, a female wasp hunts down a hapless spider by the euphonious name of Plesiometa argyra and paralyzes it for 10 or 15 minutes with a sting. In that quiet quarter of an hour the wasp lays an egg, gently attaches it to the spider's belly and departs.

在美麗的哥斯達黎加，有一種叫寄生黃蜂的寄生蟲，當它想要繁殖時，雌蜂就會窮追不捨直至抓獲一隻蜘蛛，這種倒黴的蜘蛛有一個動聽的名字叫Pleesiometa argyra。寄生蜂隨後會用它的刺麻痹蜘蛛10到15分鐘，在這蜘蛛失去知覺的這段時間裏，寄生蜂會產下一顆卵，再輕輕地把它粘附在蜘蛛腹部然後離開。

When the spider recovers it goes about its business as though nothing has happened. Perhaps it doesn't remember; perhaps it doesn't want to remember. All the while that wasp egg is incubating. A week or two later, the intermission is over, and things go rapidly downhill for Plesiometa. The wasp larva hatches, stabs a hole in the spider's stomach and begins feeding off it. In a particularly diabolical move, the larva extracts one last resource from the spider before murdering it. The infant wasp injects some kind of psychoactive substance that convinces the poor thing to spin a very un-Plesiometa-like web. When it's done, the wasp kills the drug-addled arachnid, eats it and then uses the freshly spun web to wind itself into a cocoon. Less than two weeks later a fully grown Hymenoepimecis argyraphaga emerges, prepared to propagate in the same horrific way. Isn't nature wonderful?

蜘蛛恢復知覺後，就像什麼都沒發生過一樣。或許它真的什麼都不記得了，也或許它根本就不想記得。黃蜂的卵就一直這樣靜靜地孵化着。一兩個星期後，這種平靜被打破，蜘蛛的處境急轉直下。寄生黃蜂的幼蟲孵化出來後，就用刺刺穿蜘蛛的胃，並從中取食。更喪心病狂的是，黃蜂幼蟲在殺死蜘蛛前會將其榨取得一絲不剩。它向蜘蛛注射一種神經活性物質，誘惑其給它織一張形狀完全不同於平時的新網。織完網後，黃蜂幼蟲就會殺死蜘蛛並將它吃掉。接着把新織的網纏繞成一個繭，將自己包裹其中。不到兩週的時間，黃蜂幼蟲便可發育成熟，破繭而出。接着又準備重複這一驚悚的繁殖之路。大千世界無奇不有吧！

ting Over

2.斷肢再生的海星

If, like seahorses, starfish look like creatures from a fairytale, the venomous invertebrate known as the crown-of-thorns belongs in one of those old, sinister Brothers Grimm versions.

如果海星像海馬一樣，也是童話裏纔出現的生物，那麼棘冠星魚這種有毒的無脊椎動物，也只會出現在暗黑系的老舊格林童話版本中。

Crown-of-thorns starfish (or more properly, "sea stars") eat coral reefs. Because of human activities such as overfishing of their natural predators, they can sometimes undergo a population explosion. This, in turn, can result in the complete destruction of a reef. Not only will this mean the loss of habitat for the many creatures that make their home in reefs, but the local tourist industry can be hit too. To combat the problem, there have been various efforts the kill off the excess crown-of-thorns. On the Great Barrier Reef, for instance, divers started off by chopping the invertebrates into little pieces. The plan backfired because of the sea stars' remarkable ability to regenerate. Not only can they regrow lost limbs, but under the right circumstances, they can grow a whole new body from a severed limb. That's because their cells are "indeterminate," which means they retain the ability to form new body parts, just as our embryonic cells did when we were first developing. Now, if only we could master this regeneration thing — not only could we regrow lost limbs, we could generate whole new ones. Who couldn't use an extra pair of arms? Things would be a little weirder, though, if those disembodied arms grew a new you.

棘冠星魚（稱作“海洋之星”更爲貼切）會吞食珊瑚礁。且由於過度捕撈它們的天敵等人類活動，導致這種海星時不時出現爆炸性增長，而珊瑚礁卻因此遭受滅頂之災。這不僅意味着許多依附珊瑚礁生活的生物將失去棲息地，對當地旅遊業無疑也是沉重的打擊。爲了解決這一難題，人們嘗試做出各種努力，意圖消滅過量的海星。比如說在大堡礁，潛水員們把這些無脊椎動物砍成了一小片一小片的，希望這樣可以殺死它們。然而事與願違，這種海星的數量根本沒有減少，因爲它們有着可怕的再生能力 。它們不僅能使斷肢重生，在合適的條件下，斷肢甚至能再生成一個完整的全新的個體！因爲它們的細胞具有高度全能性，就像我們人類生命形成之初的胚胎細胞一樣，這意味着他們具有再生成新個體的能力。如今，我們若能掌控這種再生能力，那不僅能再生出身體受損的部位，甚至還能創造出一羣全新的個體。誰不希望有三頭六臂呢？然而，斷掉的手臂就能長成一個嶄新的自己，確實非常詭異！

unity Gendering

1.調控性別的海金沙

Teenagers can procreate. Terrified by this prospect, their parents often seek to exert whatever control they can over their children's sex lives. From a teenager's perspective it's all rather annoying having old farts incessantly minding your business. But before sighing heavily and rolling your eyes at mom's intrusions, spare a thought for the Japanese climbing fern. Compared to them you've got it easy.

青少年已經具有生育能力了，父母們爲了避免孩子們偷食禁果帶來不良後果，總會想盡一切辦法干涉孩子們的性生活。從青少年的角度來講，也許你會覺得有一羣不斷干涉自己生活的長輩簡直是世界上最鬧心的事兒。在你哀嘆不已，朝你那嘮嘮叨叨的老媽翻白眼之前，想想悲劇的海金沙，你就會暗自慶幸了。

Fully grown ferns are called gametophytes, and they can be males, females or hermaphrodites if there are no other breeders around to help out. But, of course, self-fertilization is the very incarnation of inbreeding, a situation to be avoided whenever possible. So, when little fernlings are growing, older females in the neighborhood can secrete a chemical called gibberellin, which causes the surrounding youth to turn into males. Thus the grown-ups control the gender balance to maintain a healthy genetic diversity. Of late, the word "community" has become a buzzword for all that is positive and necessary in 21st century life — perhaps the sex life of climbing ferns demonstrates that community involvement might have its limits!

完全成熟的蕨類植物被稱作配子體，它們可以是雌性，也可以是雄性，甚至當周圍環境沒有配偶完成繁殖時，它們也可以是雌雄同體。但自體受精畢竟是近親交配的一種形式，所以自然是要竭力避免的。因此，在海金沙幼苗成長的過程中，周圍成熟的雌性植株會分泌一種名爲赤黴素的化學物質,誘導這些幼秒生長成雄性植株。成熟的海金沙就通過這種方式調控性別平衡，維持羣落內部合理的基因多樣性。近來，“羣落”、“社區”成爲一個流行詞，用來象徵21世紀的生活中，那些帶來正能量且爲人們所需要的東西——然而海金沙的繁衍方式或許正揭示了社羣生活也有其侷限性。

審校：suyiee 來源：前十網