In her new book, Venomous: How Earth’s Deadliest Creatures Mastered Biochemistry, scientist Dr. Christie Wilcox writes about a unique type of insect found primarily in Brazil, the Lonomia obliqua, a/k/a the “assassin caterpillar.” This moth-to-be is unlike most caterpillars, in that it doesn’t have a furry appearance, instead they’re covered with what looks like small trees. They’re actually pretty cool-looking, but don’t even think about picking one of them up, as inside the tip of each spiky “branch” is a deadly venom.
 

 
Getting pricked by one of these caterpillars isn’t exactly ideal, but to make matters worse, they usually gather in bunches, so the unsuspecting who brush up against them are actually stung multiple times. Once that happens, the insects’ venom enters the bloodstream and causes over-clotting. What look like bruises will soon appear, the result of internal bleeding. Other symptoms include pain, swelling, headache and vomiting, but that ain’t the worst of it. After a day or so, all that over-clotting will cause the victim to run out of blood platelets, resulting in a death that is fucking horrifying.

Dr. Wilcox:

Without those platelets available to form clots when needed, the envenomated victim bleeds. Uncontrollable. Even there’s though there’s no wound to be seen. [The sufferer can experience] bleeding mucous membranes in the nose and eyes, bleeding from scars, and even internal bleeding into the brain.

Holy shit, right? Perhaps most upsetting of all is that if you are pricked by multiple caterpillars and end up experiencing this harrowing ordeal, you—and whoever you are with—will likely have no idea what is going on. Aside from the fact there won’t be any visible wounds, most people who are stung don’t feel it, so even though there is an antivenom available, the need might not be realized, if at all, until it’s too late.
 

 
This killer caterpillar was profiled in the four-part Animal Planet series, Nature’s Deadliest. Watch and learn, people: