* Thorns: Sharp, pointed structures that deter animals from biting or chewing on the plant. Think of roses, cacti, and hawthorn bushes.
* Spines: Similar to thorns, but these are modified leaves, not stems. You'll find them on plants like holly and agave.
* Prickles: Smaller, softer, and less sharp than thorns or spines. They are found on plants like raspberries and roses, and can irritate the mouths of animals.
* Hairs: Tiny, bristle-like structures that can be irritating or even poisonous to animals. Some plants, like stinging nettles, have hairs that release chemicals that cause pain.
* Tough leaves: Some plants have leaves that are thick, leathery, or fibrous, making them difficult to chew.
* Unpleasant taste or smell: Many plants produce toxins or chemicals that give them a bitter taste or unpleasant odor, making them unappealing to animals.
* Waxy coatings: Some plants have a waxy coating on their leaves and stems that makes them slippery and difficult for animals to grip.
It's important to note that many plants have multiple defense mechanisms, and some plants even use camouflage or mimicry to avoid being eaten.