Chemical defence mechanism exists in the animal world
Jan 16 2013
But the use of chemical defence for survival in nature has been prevalent since evolution. Plants and animals have used it since evolution and benefited.
Most chemical defence mechanisms fall between two extremes, that of lethal toxins or distasteful compounds that would shun the predator away. These compounds are either endogenous, which are produced by the organism such as the venom in snakes and scorpions or exogenous products of other organism such as the monarch butterflies, that protect themselves from their predators using milkweeds. During the 1960s, researchers discovered that cardenolides are chemicals in milkweed that made monarchs toxic and bitter tasting. Since many adult monarchs do not eat milkweed, it shows that they had stored the repulsive chemicals that they ingested as larvae and proved to give the protection during its butterfly stage.
There are many other known species that protect themselves with chemical defence. These are common such as snakes, spiders, scorpions, bees, stingrays, centipedes, anemones, ants and snails among others. Interestingly, an entirely new family of chemical structures, characterised as alkanoic acid derivatives, was discovered as the working ingredients of the chemical defence system used by ladybird beetles. The beetle’s pupae utilise an interesting chemical defence mechanism consisting of oily droplets at the tips of glandular hairs that coat the beetle. The oily secretion is especially deterrent against ants. The chemical composition of the secretion consists of ester and amide compound alkanoic acid derivatives, mainly macrocyclic polyamines.
Most organisms manufacture complex mixtures of chemicals for defence, some of which may actually be inactive as pure compounds. Humans tend to prefer highly active individual components. It is, perhaps, the ecologically inappropriate deployment of these natural products (and their synthetic derivatives) by humans that has led to the widespread acquisition of resistance in all manner of target species and the affiliated loss of effectiveness of these chemicals.
Ironically, many other poisonous animals have serious potential in the development of medicines and medical treatments.
This chemical weaponry can be used against disabling and life threatening diseases and illnesses for the future. The toxin found in bee venom has the ability to kill tumor cells
Venomous insects and animals are proving to be extremely beneficial to humans suffering from chronic pain, muscular dystrophy and some types of cancers. These toxic venoms are also used in protecting crops from harmful insects.
Humans have, in recent years, developed a tendency to use chemical defences and sometimes even when the enemy is absent. But this may not be the case with these creatures that use these weapons only to protect themselves from predation. Besides, humans tend to select those chemical agents that kill, rather than prevent or misdirect. From an animal’s perspective, the ultimate goal of chemical defence is to avoid being eaten.
(The writer is a conservation biologist at Tiger Watch, Ranthambore)