Intravenous Injection of Chemotherapy. It is very common for chemotherapy medications to be injected into a vein, or intravenously. In many cases, a nurse or doctor will insert a needle into your vein, often in your hand or arm, and the chemotherapy will be given through there.
2. Poison Dart Frog. Of all the poisonous animals in the world, these are probably the easiest to spot due to their extremely bright colors, including yellow, blue, green, & red. These frogs don't actually inject their poison through their mouth; they do it through their skin.
One animal is more venomous than any other. Snakes are famous for their venom, and justifiably so. Injected directly into the flesh by inch-long fangs or needle-sharp harpoons, venom is weaponised chemistry. In any list of the world's most venomous animals, snakes often get top billing. Not all snakes are venomous, but certain groups have evolved to channel toxins through grooves or tubes in their teeth.