It seems your autofocus has problemd to find the snakes head. As you can see, the back part and mainly the ground is in focus.
Some "workarounds":
If the camera misses the head:
a) Put the head in the center of the cam, try to get it in focus, keep the button pressed and arrange the photo. That way, the focus from the head shouldn't get lost.
If you are too near for the autofocus:
b) Try getting farer away and keep the "zoom".
c) Stay near, but do not zoom.
Both of these ways are to work around the minimal distance between the object and the cam, which is different when you "zoomed-in" or not.
If you ask me, try to get a little bit farer away, use a flashlight and crop the picture afterwards on your computer to get the picture done. Thats not good if you want to have larger prints of the pictures, but good enough to show them off in the internet. If you are interested in larger prints, go with a) and c) and find out at which is the minimal distance to the snakes head your camera can handle, focus it and the slightly move the camera vertically and horizontally to arrange the pic.
I hope this is understandable, if not, a native speaking photographer may correct me - please!
Greetings
Michael