Yes, this snake is eating its own tail.

Says one Redditor:

I used to own a Ball Python, and I will tell you once something goes inside its mouth, it can't be removed without a lot of effort. Their teeth hook backwards so any prey that is still alive can't struggle out of their mouth once they are in there:

I'm not a herpetologist, and my experience is just with my one snake... but I'm gonna say that this snake will not be able to remove its tail from its mouth without assistance.

Apparently, it can happen accidentally and the snake can't get out of the vicious circle by itself.

See also: http://en.wikipedia.org/wiki/Ouroboros

Ouroboros memes