Toxins and venoms: nature's poisons

WITH EVOLUTIONARY BIOLOGIST JV CHAMARY

- JV CHAMARY

WHEN ASKED TO NAME substances that cause sickness or death, many people would mention. poisons that are harmful to humans - chemical elements such as arsenic, plants such as hemlock, or death cap mushrooms. In fact, nearly every major group of organisms makes natural poisons, which come in two flavours: toxin and venom.

What's the difference between a toxin and a venom?

They're distinguished by delivery route. A toxin passively enters a recipient's body after being swallowed, inhaled or absorbed through contact. By contrast, a venom is actively delivered into a victim via a bite, spray, stab or sting. But you can't simply. say that toxins are ingested and venoms are injected. When the toxin tetrodotoxin is delivered through the bite of a blue-ringed octopus, it's then technically venom! The two poisons also differ by function.

Toxins are typically used for defence, to deter predators or competitors, venoms are used for offence, to catch prey. They have different compositions, too. A toxin is typically a single molecule and a venom is a mixture that will include toxins. Marine cone-snail venoms can contain over 100 distinct toxins to target a variety of prey.

Where do they come from?