* What kind of animal are you thinking of? A mammal, bird, fish, insect, reptile?
* What type of defense are you interested in? Physical defenses like claws or venom, or behavioral defenses like camouflage or warning calls?
* What is the specific threat the animal is facing? Predators, rivals, or environmental dangers?
Once I have more information, I can give you some specific examples of animals that can protect themselves!