Animals are the greatest hazards in the pyramid of RA. In addition to being dangerous, they can be quite confusing if you don't know what to expect.
The first thing to know is that animals often move faster than you do. This means they may take two or more steps for each one of yours. If you are looking at an animal, and then do something which takes time, and the animal moves during that time, then you will see the animal move. This game doesn't do any animation, so when an animal moves, you will see the "Scarab of RA" window re-drawn briefly for each step the animal takes. If you were trying to take a step yourself, you will see your own move first, then the animal's moves afterward. So don't be startled when your view "flickers" several times when you only clicked the mouse once!
Because they are so fast, animals can come up behind you, and strike before you know they are there. They can then turn and run off, so quickly you will have no chance to see them. This won't happen often, but it may happen if you are hit just as you go around a corner.
The last important thing about animals is really an important thing about the author of the game, who is tired of using computers to kill things (even though they are all only imaginary). There is no way to kill the animals in the Great Pyramid of RA. You must find less violent solutions!
Animals can be quite difficult to deal with. Don't get too upset; remember that they are intended to give you a hard time! If you get terribly frustrated, read the "Hints on Animals" section about tactics for dealing with animals.