Meet a creature that looks like a miniature dinosaur and defends itself by shooting a five-foot, highly pressurized stream of foul-tasting blood directly out of its own eyes. The horned lizard is an armored desert tank perfectly engineered for survival, yet this seemingly indestructible warrior is rapidly vanishing, brought down not by predators but by suburban lawns and tiny invasive ants.

We use the horned lizard as a case study in the limits of extreme adaptation, exploring how a body built flawlessly for one harsh world becomes a fatal liability when the rules of that world change. It is a striking lesson in what survival of the fittest actually means.

• Rain harvesting through skin: how capillary channels between scales route water across its back straight to its mouth
• The escalating defense matrix, from freezing camouflage to puffing up like a spiky balloon to the nuclear blood-squirting option
• The biology of squirting blood: clamping jugular veins to spike cranial pressure until eye vessels rupture, foul to canines but not birds
• A dietary Achilles heel: the lizard needs venomous harvester ants and will starve with a stomach full of crickets
• How invasive fire ants and the pesticides used to fight them wipe out the native ants the lizard depends on