...or how the design just fascinates me to no end.

I've always held that the cat family is one of the most perfect designs in nature (and hominids one of the crappier). Case in point.



Hobbes is shown here asleep in a tree, an artificial tree but a tree nonetheless. As long as he instinctively feels he is high up enough that rolling off is dangerous, his tail naturally curls under with the tip at the horizontal and at his centre of mass, creating a pendulum so that the change in relationship would automatically and unconsciously register if he starts rolling off, thus waking him up before something bad happens.

Here...



...he has awakened, rolled over, and gone back to sleep, the tail back in it's balance-indicator position as before, proving this isn't just a fluke and a cool photo opportunity, but a real instinctive behaviour. It isn't just the house-and-mouse crowd, but big cats often do this; photos of jaguars and leopards sleeping across a tree-branch will show this.

Ones Hobbes hits REM sleep, he is relaxed enough such that the tail might slowly go slack to hang down to the vertical...



...but never gets pulled up as long as he feels the need for that pendulum/auto-pilot.

Genius.