This week’s bizarre beast is likely the most known that we’ve covered so far. Everyone is familiar with poison dart frogs, but how much do we really know about them? Many people know they are poisonous, as their name implies, but how poisonous are they really?

The answer depends on the background of the individual frog. When I lived in Costa Rica for a brief internship, I was fortunate enough to meet some individual frogs in my travels. We lived in some of the lowland rainforests, and certain species of the frog, such as the strawberry poison dart frog (Oophaga pumilio) pictured above. This poison dart frog is known as a “blue jeans” morph of its species, because, well, it looks like it’s wearing little frog pants, which is adorable. You can see how truly tiny they are (or, perhaps, how gigantic my friend and his camera might be) and yet, they march fearlessly into open areas.

Their bright coloration is part of its aposematism (Wikipedia coincidentally pictures a blue jeans morph strawberry poison dart frog as its poster child of the concept), which warns would-be predators as if to say “don’t eat me, I’m totally gross and you’re going to hate this and then die,” an honest signal from the frog. When we handled these frogs, I kept a mantra in my head: “wash your hands, wash your hands, don’t touch your mouth, wash your hands” for the rest of the day due to the toxin being left on my hands. I did eventually wash them and then went to bed.

I woke up the next day with crippling stomach pains. “Well, I’m dead,” I thought. I spent the rest of the day panicking before realizing my stomach was just getting used to the food and water in the area. Phew. Luckily, that frog isn’t the worst of the poison dart frogs, either.

The golden poison dart frog (Phyllobates terribilis) of Colombia takes the cake for the most deadly of the poison dart frogs. These frogs, like many other related frogs, are used by indigenous people to tip their darts and arrows for hunting. Each frog can produce a milligram of toxin, enough poison, by some estimates, to be able to kill fifteen humans. This means a gram of the poison, about the weight of a small paperclip, has the potential to kill fifteen thousand humans.

The poison of most poison dart frogs works by blocking nerve activity. It can stop nerves from being able to fire entirely, or interrupt their action, so many animals that mistakenly eat poison dart frogs may die of fibrillation, which is when heart muscles are unable to synchronize and fire erratically, stopping your heart. This is why the life-saving tool that re-synchronizes your heartbeats is called the defibrillator!

Interestingly, if kept in captivity, that same golden poison dart frog that could have killed fifteen people could be absolutely harmless after a few years (though sometimes longer). But why? For a very long time, scientists had no idea what caused the toxicity of the frogs, but within the last decade or two, scientists have finally found the answer: their diet. The frogs eat a multitude of arthropods, but it turns out alkaloid defensive compounds in certain ants they were eating were being sequestered in their skin! Within the last decade, it’s been discovered that ants seem to be the key linking species of poison dart frogs around the world. Without their diet of ants, the frogs are unable to produce their poison, thus, many poison dart frog species are raised in captivity and are entirely safe to handle and even eat, if you’re some kind of weird monster who eats their tiny terrarium pets.

While each type of poison dart frog attempts to warn predators of its toxicity, the variety of colors and patterns by which they do is very breathtaking. Here’s a quick clip of some of the variety among poison dart frogs in just a small area of the Caribbean, courtesy of the BBC: