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Coming up next on Jonathan Bird's Blue World, Jonathan explores the fascinating biology of skates and rays!
接下来请收看乔纳森·伯德的《蓝色世界》，乔纳森探索迷人的鳐鱼的生理习性！
Hi I'm Jonathan Bird and welcome to my world!
嗨，我是乔纳森·伯德，欢迎来到我的世界！
You know me...I love sharks!
你们都了解我，我超爱鲨鱼！
It doesn't matter if it's a big shark like the Great White or whale shark, or if it's a small one like the white tip reef shark.
不管是像大白鲨或鲸鲨这样的大鲨鱼，还是像白尖礁鲨这样的小鲨鱼。
Sharks are cool!
鲨鱼太酷了！
Skates and rays are the evolutionary cousins of sharks—they are contained within the class Chondrichthyes along with the sharks, but they are in their own sub-division known as the Batoids.
鳐鱼是鲨鱼在进化中的近亲，它们和鲨鱼一起归属在软骨鱼纲中。但它们属于各自的一个分支，即蝙蝠状鱼。
The Batoids share many characteristics with sharks, such as the cartilaginous skeleton, the lack of a swim bladder and multiple gill slits.
蝙蝠状鱼与鲨鱼有许多共同特征，如软骨骨骼、没有膀胱，具有多个鳃裂。
In fact, they are so similar that you almost could think of them as flat sharks.
事实上，它们是如此相似，几乎可以把它们想象成扁状的鲨。
But there are some flat sharks.
但是有一些扁平状的鲨鱼。
The Wobbegong shark, for example, actually looks more like a ray than a shark, because it's flattened and tends to lie on the bottom.
例如，须鲨科的鲨鱼看起来更像鳐鱼，而不是鲨鱼，因为它是扁平状的，而且往往停留于海底。
So how do you tell a ray from a flat shark?
那么，如何分辨鳐鱼和扁平状的鲨鱼呢？
First of all, skates and rays are always flat.
首先，鳐鱼总是扁平状的。
Biologists call them dorso-ventrally flattened.
生物学家称它们是背腹扁平。
But unlike a dorso-ventrally flattened shark, a skate or ray has wing-like pectoral fins that are just an extension of its body, making it look a bit like a flying carpet.
但与背腹扁平的鲨鱼不同的是，鳐鱼的胸鳍像翼，只是身体的延伸，使它看起来有点像飞毯。
Or maybe if you squint a little, a bat, hence the name “Batoids.”
或者，如果你斜瞟的话，有点像蝙蝠，因此叫做“蝙蝠状鱼”。
Also, skates and rays have their gills on the underside of their bodies, while a shark—even a flattened shark--has them on the side.
此外，鳐鱼的鳃位于身体的下方，而鲨鱼，甚至是扁平状的鲨鱼，它们的鳃位于身体的侧面。
One of the most well-known rays is the stingray.
最著名的一种鳐鱼是黄貂鱼。
This is a Southern Stingray, common in the Caribbean.
这是南部黄貂鱼，在加勒比海很常见。
It gets its name from its stinger—a sharp venomous spine at the base of the tail.
它的名字来源于它的刺，它的尾巴底部有一根锋利的毒刺。
This powerful weapon is used to defend the animal from its most feared predator—sharks!
这个强大的武器可以用来保护它们免受最可怕的掠食者鲨鱼的捕食！
Wait a minute!
等一下！
Sharks eating their own evolutionary cousins?
鲨鱼会吃自己在进化中的表亲吗？
That is so uncivilized!
这也太不文明了！
The Southern Stingray feeds on animals that live in the sand, like mollusks and worms.
南部黄貂鱼以生活在沙中的动物为食，如软体动物和蠕虫。
The stingray's mouth is on its underside, just like its gills.
黄貂鱼的嘴在它的下面，就像它的鳃一样。
It blows water into the sand to excavate around prey, then slurps it up with powerful suction.
它把水吹进沙子，在猎物周围挖，然后用强大的吸力把它吸上来。
Because it feeds in the sand, the Southern Stingray tends to swim close to the bottom, though it certainly doesn't have to.
因为它们以沙子为食，南部黄貂鱼往往会游到接近海底的地方，尽管它们不用这么做。
But this poses a problem—with breathing!
但这会给带来一个问题，那就是呼吸！
A shark breathes by taking water in through its mouth and then sending it back out through the gills to extract oxygen from the water.
鲨鱼通过口吸入水，然后通过鳃把水送出体外，提取出水中的氧气来呼吸。
However, since the stingray has its mouth on its underside and swims so close to the bottom, you would think that the stingray would get a lot of sand into its gills.
然而，由于黄貂鱼的嘴在下面，游得离海底非常近，所以你会认为黄貂鱼的鳃里会有很多沙子。
And you would be right, except for one thing.
你这么想就对了，但有一件事除外。
On top of the stingray's head are a pair of openings called spiracles.
在黄貂鱼的头顶上有一对称为尖塔的开口。
They are kind of like big nostrils.
它们有点像大鼻孔。
Instead of breathing in through its mouth, the stingray breathes in through the spiracles on top of its head and away from the sand.
黄貂鱼不是通过嘴呼吸，而是通过头顶的尖塔呼吸，远离沙地。
Sharks have spiracles too, but they are really small on most sharks, and they can't breathe through them.
鲨鱼也有尖塔，但在大多数鲨鱼身上都很小，不能通过它们呼吸。
The only sharks that breathe through their spiracles are—you guessed it!
只有鲨鱼通过尖塔呼吸，你猜对了！
Flattened bottom dwellers like the Wobbegong!
像须鲨科的扁平状鲨鱼！
