Venom and poison.Many animals can produce actual poisons and venoms, substances, which, even in very small amounts, can kill, cripple or otherwise harm other animals. The ability to produce toxins has been developed in all the major animal groups, except for the birds, but in reality, only few of the animals that use chemical weapons can bother us. We are simply too large and thick-skinned. The venomous and poisonous animals have developed special organs, stingers, spines or hooks to get its venom or poison into the victim. The toxin is produced in special glands. They are complex fluids, all the components are not known, but there are various kinds proteins and complex sugars in them. The venom of the European adder contains hemolysin substances (which color the skin blue). The venom of the greater weever contains a substance, which causes the small blood vessels to contract. With ants and in the hair of the Rusty Tussock Moth, formic acid is one of the skin-irritating substances (like with stinging nettles).
Saliva. Blood-sucking insects and mites always inject saliva in the wound while sucking blood. Saliva is a complex fluid containing agents with very different effects.
The saliva of some bloodsuckers (caster bean tick, medicinal leech, etc.) contains local anesthetics that can make an otherwise clumsy bite painless. In the saliva of all bloodsuckers, there are agents that can prevent blood from coagulating. Digestive enzymes are a characteristic component of saliva. The greatest amounts of these enzymes are injected into humans when bitten by animals which partly digest its prey before eating it (water bugs, kissing bugs, fur mites, asparagus spider mites, etc.).The saliva might also contain actual toxins, thus there is a paralyzing agent of the curare-type in the caster bean tick saliva