Natural toxins are toxic compounds that are naturally produced by living organisms. These toxins are not harmful to the organisms themselves but they may be toxic to other creatures, including humans, when eaten. These chemical compounds have diverse structures and differ in biological function and toxicity.

Mithridatism is the practice of protecting oneself against a poison by gradually self-administering non-lethal amounts. The word is derived from Mithridates VI, the King of Pontus, who so feared being poisoned that he regularly ingested small doses, aiming to develop immunity.

Snakes are elongated, legless, carnivorous reptiles of the suborder Serpentes. Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have evolved elongate bodies without limbs or with greatly reduced limbs about twenty-five times independently via convergent evolution, leading to many lineages of legless lizards.Legless lizards resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal.

Poison is any substance that is harmful to your body. Many different types of poison exist. Poisonous substances can be products you have in your house. Medicines that aren’t taken as directed can be harmful. There are several ways you can be exposed to poison. You could breathe it in, swallow it, or absorb it through your skin. Poisoning can be an accident or a planned action.