Animal defense strategies

Abstract

Animals rely for their defense on physical strength, an armored body, hiding, or the production of toxins. Actively defending organisms expose their defense compounds against the enemy, for example, by a sting apparatus. Passively defending animals, instead, generate toxic compounds that exert their potential if they are eaten, ensuring that the attacker does not continue feeding on this species. The defense compounds of many animals are often structurally relatively simple but efficient, for example, quinones. Many compounds act as inhibitors of the respiratory chain, influence ion channels, or comprise reactive dialdehydes and Michael acceptors that destroy proteins. Such reactive compounds are stored as inactive precursors to avoid self-intoxication.In rather rare cases, structurally complex defense compounds such as the polyketide pederin are used for defense by animals. The occurrence of complex defense compounds among animals may point to a symbiotic contribution by microorganisms. Very often, defense compounds are sequestered, for example, leaf beetles and lepidopteran larvae take up toxins from the food and use them for their own defense.Sometimes defensive compounds are transferred to the offspring and thus provide protection, for example, of immobile eggs. During mating, some males transfer defensive compounds such as cantharidin to the female, which in turn gives them to the offspring.