Chemical defense

Chemical defense is the use of chemical compounds by plants and animals to deter herbivory and predation. Chemical defenses can also be used in competitive interactions to prevent overgrowth or maintain spatial dominance.

In plants

Chemical defense against herbivory is common. The production of capsaicin in many strains of bell peppers is one such defense familiar to humans.

In animals

Chemical defense is most common in insects, but the skunk is a particularly dramatic mammalian example. Other examples include the bombardier beetle which can accurately shoot a predator with a stream of boiling poison, the ornate moth which excretes a frothy alkaloid mixture, and the Pacific beetle cockroach sprays a quinone mixture from modified spiracles.

Marine invertebrate animals also harbor chemical defenses that protect them from predators, particularly tropical marine sponges,^[1] gorgonian corals,^[2] nudibranch molluscs,^[3] and tunicates.^[4]

References

1. Pawlik, J. R. (2011). "The chemical ecology of sponges on Caribbean reefs: Natural products shape natural systems.". BioScience. 61: 888–898. doi:10.1525/bio.2011.61.11.8.
2. O'Neal, Will; Pawlik, Joseph R. (September 12, 2002). "A reappraisal of the chemical and physical defenses of Caribbean gorgonian corals against predatory fishes". Marine Ecology Progress Series. 240: 117–126. doi:10.3354/meps240117.
3. Pawlik, J.R.; et al. (1988). "Defensive chemicals of the Spanish Dancer nudibranch, Hexabranchus sanguineus, and its egg ribbons: Macrolides derived from a sponge diet.". Journal of Experimental Marine Biology and Ecology. 119: 99–109. doi:10.1016/0022-0981(88)90225-0.
4. Pisut, D,P.; Pawlik, J.R. (2002). "Anti-predatory chemical defenses of ascidians: secondary metabolites or inorganic acids?". Journal of Experimental Marine Biology and Ecology. 270: 203–214. doi:10.1016/S0022-0981(02)00023-0.