未出生的幼鯊會在子宮之間游動，吞食兄弟姐妹

未出生的幼鯊會在子宮之間游動，吞食兄弟姐妹

As macabre as it seems, it's not exactly a secret that in some species of shark the unborn dine on their siblings while still developing in the womb.

盡管看起來令人毛骨悚然，但在某些種類的鯊魚中，未出生的幼體在子宮內(nèi)發(fā)育的同時，卻以兄弟姐妹為食，這并不是什么秘密。

But it turns out we don't know the half of it. A novel kind of ultrasound device has provided biologists with a detailed view of this common act of cannibalism, and in 2018 it revealed they don't just nibble on their neighbour. Embryos will travel between wombs to feast.

但事實證明我們只知其一不知其二。一種新型的超聲波裝置為生物學家提供了這種常見的食人行為的詳細視圖，并在2018年揭示出它們不僅僅是在蠶食它們的鄰居，胚胎還會在子宮之間游走以飽餐一頓。

No, that's not a typo. Many species of shark mature their eggs or gestate embryos in a left and a right uterus.

是的，我沒打錯字。許多種類的鯊魚用左子宮和右子宮來孕育它們的卵或胚胎。

(Tomita etal/Ethology)

For most animals, embryonic movement is rather limited to a bit of squirming and the occasional flip. Even for young that aren't anchored to a placenta, gestation is thought to be a rather sedentary affair.

對大多數(shù)動物來說，胚胎期的活動相當有限，只有一點蠕動和偶爾的翻轉(zhuǎn)。即使對于沒有固定在胎盤上的嬰兒，妊娠也被認為是一種相對靜止的事情。

So researchers from Okinawa Churaumi Aquarium in Motobu, Japan, were surprised to find the unborn pups of captive tawny nurse sharks (Nebrius ferrugineus) not only moving around their own uterus, but moving house altogether.

因此，來自日本Motobu市沖繩縣美之海水族館的研究人員驚奇地發(fā)現(xiàn)，圈養(yǎng)的黃褐色護士鯊(Nebrius ferrugineus)未出生的幼崽不僅在自己的子宮里動來動去，而且還在搬家。

The discovery came courtesy of a fancy new piece of equipment that allows the kind of ultrasound device you'd use to scan a human pregnancy to be packed up and carried underwater.

這一發(fā)現(xiàn)得益于一種新穎的設(shè)備，這種設(shè)備可以將你用來掃描人類懷孕的超聲波設(shè)備打包并運到水下。

Over several years, the researchers studied a trio of pregnant tawny nurse sharks on display in an aquarium exhibition tank, capturing more than 40 ultrasound clips.

幾年來，研究人員研究了在水族館展覽池中展出的三只懷孕的黃褐色護士鯊，捕捉了40多個超聲波片段。

The results provided a family album on a time line, where up to four pups could be seen wiggling about inside each mother.

研究結(jié)果提供了一個按時間排列的家庭相冊，在相冊中可以看到多達四只幼崽在各自母親的身體里扭動。

In one mother, embryos swapped sides three times. In another, the movement was far more extreme – a total of 24 migrations were recorded across the duration of the pregnancy.

在一個母親身上，胚胎交換了三次。在另一個母親身上，這種移動則更極端——在整個懷孕期間共記錄到24次遷徙。

(Tomita etal/Ethology)

One of the scans showed the actual room swap taking place, showing an embryo hurriedly pushing its way from one uterus to the other.

其中一項掃描展示了真實的遷徙過程，顯示了一個胚胎從一個子宮快速地移向另一個子宮。

We're not talking a leisurely stroll here either. The pup swam at a speedy eight centimetres per second.

它們可不是在閑庭散步，這個胚胎以每秒8厘米的速度游了過去。

One of the female sharks started her pregnancy with two pups in each uterus. After some back and forth, four soon became three. Just under two months later, there were two.

其中一只雌性鯊魚開始懷孕時，子宮里各有兩只幼崽。來回幾次之后，四個很快變成了三個。不到兩個月，就只有兩個了。

By the end of the gestation just a single, no doubt smugly satisfied, winner remained.

到妊娠期結(jié)束時，毫無疑問，只有一個得意的贏家留了下來。