Call it reflex bleeding, call it autohemorrhaging. Whatever you call it, it’s where a creature deliberately squeezes blood from its body when its back is against the wall. 

Sometimes their blood oozes like a slow, grody punch. Like blister beetles, who defensively bleed a toxin called cantharidin from their joints when confronted with predators or blister beetle-gathering humans. 

Cantharidin gives humans blisters and burns in low doses, but it’s lethal in larger doses. That doesn’t stop us from eating it, though. For millennia, humans have been smashing blister beetles into a powder called Spanish fly and then consuming it as an aphrodisiac (and sometimes killing ourselves and/or lovers in the process).

Blue-green beetle on a light blue background, with cantharadin oozing from its joints, saying "Oh common, how about wine and chocolate like a normal person?!"

Other times, the blood shoots like a macabre squirt gun. Horned lizards can shoot toxic blood from their eyes up to five feet.

Something out of frame saying "Art! Woof!" to which a horned toad replies "Drink my tears of death, ya chump!" on a pale yellow background. The toad is brown, with blood spurting from its eye.


And other times, still, reflex bleeding works only as demonic-looking defensive display. Pygmy boas, small, nonvenomous snakes, have a whole bloody ritual. 

A blue-green snake, oozing blood, on a blue background, saying "Look into my eyes and gimme a little kiss"

If you grab one, first, it’ll poop on you. “Take this!” it says. “That’s the best you can do?” you say. 

Then, it’ll release stink musk on you. “And that!” says the tiny snake. “That’s nothing!” you reply. 

That’s when the situation escalates to serious. The snake’s head fills with blood. Its eyes turn red, and blood begins to drip from its tiny maw. 

“The horror!” you scream, throwing it on the ground. “Sike!” says the snake, slithering away. “Sucker!”

All this bleeding is an attempt at avoiding hardcore bloodshed from actual combat. Dastardly? Or divine!  



Written by Roar and illustrated by Dan Olmstead. Dan (@dolmstead) is an illustrator and photographer based in the Finger Lakes region of upstate New York. Dan has a master’s degree in Entomology from Cornell University and uses illustration as a way to help viewers more intuitively understand important aspects of science. To see more of his illustration work, visit