What are some examples of plant mechanical defenses?
Mechanical defenses work by discouraging herbivores, or plant-eaters, from consuming the plant in the first place, by harming the herbivores that do take a bite, and/or by slowing down the herbivores so that they consume less of the plant than they would otherwise. Examples of mechanical defenses include thorns on the leaf or stem, bark on a tree, and trichomes or barbs on the leaf. In some instances, a plant will protect its seeds with a tough shell (think of a coconut, a jackfruit or a pineapple). Some plants have waxy cuticles on their leaves that protect against microorganisms and insects. All of these mechanical defenses prevent and discourage others from feeding on the plant.
Some plants can use insects to protect itself. This strategy works very well. When is been attacked by a herbivore, some plants attract insects given to them something they like (nectar or something like that) to kick out the animal. It is a relation of mutualism (if you give me something - food, for exemple - I will protect you)