There are even anuses that come and go.

甚至还有一会出现一会消失的肛门。

But nature's full of exceptions, and strangely, some animals have lost their anuses.

但是自然界充满了例外，奇怪的是，有些动物失去了肛门。

As varied as the animal kingdom's anuses are, none of them have bones.

尽管动物王国的肛门种类繁多，但没有一个肛门是有骨头的。

Brittle stars and many parasites had ancestors with anuses, but no longer have them.

海蛇尾和许多寄生虫的祖先有肛门，但现在已经没有了。

Instead, from the gut, bacteria get to the rectum, anus and eventually colonizes the perineum, becoming part of the normal flora.

相反，细菌由肠道到达直肠、肛门，最终定居于会阴，成为正常菌群的一部分。

Hemorrhoids are swollen veins near the anus and rectum, which can be painful and lead to itching and bleeding.

痔疮是肛门和直肠附近的肿胀静脉，会引起疼痛并导致瘙痒和出血。

Specialized tube feet can be used for feeding and respiration, though many sea cucumbers actually breathe through their anuses.

专门的管脚可用于进食和呼吸，尽管许多海参实际上是通过肛门呼吸的。

A sea cucumber is essentially a brainless, fleshy form surrounding a digestive tract, bookended by a mouth and an anus.

海参本质上是一种无脑的肉质形式， 围绕着消化道，由嘴巴和肛门构成。

Treatment is typically surgical resection of the area that's lacking the nerve fibers, and then the healthy end is connected to the anus.

治疗疾病一般行根治手术，切除神经纤维缺失的肠段，然后将剩余肠段健康的一端连肛门。

The most widely-used definition of deuterostome has to do with how our mouths and — the SciShow comments’ favorite term — anuses develop.

最广泛使用的后口动物定义与我们的嘴巴和——SciShow 评论最喜欢的术语——肛门的发育方式有关。