If you're a mammal, you have to sleep. Now, some animals just curl up, wherever they are and catch a few Zs, but some animals sleep habits are downright odd. My dog, Hank, thinks he's part human and insists on having covers and has even taken over one of my pillows so he can rest his head on it, but he's kind of strange anyway.

In the video we see that walruses sleep while bobbing up and down in the water. it seems that they have special air sacks along their necks that, once inflated, keep them afloat while they enjoy a good night's sleep. Of course, there are the bats in the video that have special tendons that allow them to grasp a branch or other anchor and, as you know, they sleep upside-down. That's great until you pull a tendon and come crashing down on your head.

There are not a lot of animals featured in this video, but you'll find yourself relaxing as you watch how these animals sleep, so don't doze off while you enjoy watching.