Chemical defense

Chemical defense is the use of chemical substances by organisms to deter predators, parasites, or pathogens. Defenses may be produced by the organism or acquired from its food or environment.

Secondary metabolite: An organic compound that is not directly required for an organism’s basic growth or reproduction but can affect ecological interactions. Many chemical defenses are secondary metabolites that alter how predators or pathogens interact with their producers.
Poison dart frog: A group of brightly colored frogs whose skin toxins can deter predators. Some species acquire potent alkaloids from prey and sequester them in their skin.
Predation: An interaction in which one organism kills and consumes another organism. Predators are a major selective pressure that chemical defenses can reduce.
Physical defense: A structural trait that reduces damage or access by predators, parasites, or pathogens. Spines, shells, and barriers resist attackers without relying primarily on defensive chemicals.
Chemical arms race: Reciprocal evolutionary change in which organisms develop chemical defenses and their antagonists evolve ways to overcome them. Defenses can select for predators and herbivores that tolerate or detoxify their compounds.
Chemical ecology: The study of how chemical compounds mediate interactions among organisms and between organisms and their environments. It explains how defensive compounds function within ecological relationships.
Monarch butterfly: A milkweed-feeding butterfly whose larvae and adults can retain plant cardiac glycosides. Its acquired toxins make it distasteful or harmful to many predators.
Parasitism: An interaction in which one organism benefits by living on or in a host and harms it. Chemical defenses can interfere with parasites that exploit an organism as a host.
Behavioral defense: An action that reduces the likelihood or consequences of attack or infection. Fleeing, hiding, and grooming protect organisms through behavior rather than chemical deterrence.
Aposematism: The use of conspicuous signals to advertise that an organism is toxic, harmful, or otherwise unprofitable to attack. Toxic defenses can support warning signals that teach predators to avoid defended prey.

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