That all depends on the type of animal. Let's say two cats are fighting over food or a mate. Cat 1 will bare its fangs, rear up, and hiss. If this doesn't scare cat 2, they will start to bat at each other with their paws. If this makes one of them run away, the other is done defending itself. If not, they wil claw and bite until one cat either runs away or goes to Kitty Heaven. That is just one example, there are millions, if not billions, of ways animals defend themselves. If you want a violent example, here's one. Now we'll say there are two squid fighting over food or a mate. Squid 1 will change skin color to red, indicating it is strong. If that doesn't work, the squid will just Literally tear each other to shreds until one dies. The other squid will eat the mutilated remains of his opponent. Again, there are billions of ways for animals to defend themselves, these are just a few.
how do animals protect themselves from their enemies by using there mouth parts
It really depends on what sort of animal it is
They bite if attacked.
they blend in to different habitats then the other animals cant hurt them.
By throwing mud on their enemies
they raddle
????
they camouflage
TANGA
By using their tencles
Camoflauge
The makahiya protect themselves by flipping their leaves