The Texas Horned Lizard

We’re very excited to announce the latest addition to TWBE, a weekly column about the World’s Weirdest Animals by award-winning science writer and author Bec Crew, illustrated by the super-talented Aiyana Udesen!
Glue-guns. Slime blankets. Mind-altering venom, flesh-rotting chemicals, and fountains of spit so powerful, they’ll knock you off your perch and into a pair of awaiting jaws. Better grab a raincoat, because nature is positively crawling with ingenious ways of dealing out death via some carefully aimed bodily fluids.
But it’s not all bad news, because those bodily fluids can also be incredibly helpful at keeping that head on your shoulders when you’ve got little else to defend yourself with than the art of camouflage. Someone who knows this all too well is the Texas horned lizard – a tough little reptile found all across the western United States, Canada and Mexico.
With a round face framed by a halo of large horns, and a stout, tank-like body covered in spines, the Texas horned lizard looks just like a tiny, armored dragon. And while this dragon doesn’t have any jets of red-hot fire to belch at its enemies, it does have something just as intimidating to launch in their direction: blood. Blood mixed with one of the most toxic substances found in nature that comes gushing out of its eye sockets, no less.
Expelled from the eye sockets thanks to a build-up of pressure in the Texas horned lizard’s head, each of these jets can travel for over a meter in the air and can contain up to 1.5 grams of blood. A particularly harassed individual can spurt more than 50 times out of a single eye and lose more than half of its total blood supply in the process.
Known as ‘autohaemorrhaging’, the practice of deliberately ejecting blood in response to a threat is very rarely encountered in nature. A handful of insects do it, plus three species of horned lizards and two species of snakes. The way the Texas horned lizard does it has been specifically designed to repel its least favorite guys ever – dogs. For a reason that’s still unclear to scientists, the blood that shoots out of the Texas horned lizard’s eye sockets elicits a particularly strong response from its canine predators, causing inflammation and gastric distress in foxes, coyotes and domestic dogs. Its non-canine predators, such as grasshopper mice and roadrunners, are spared the blood-jet treatment.
So what’s in this special blood-based dog repellent? Texas horned lizards have a very peculiar diet – they love harvester ants. But these ants happen to be incredibly venomous, with a sting that’s 20 times worse than a bee’s. In response, the Texas horned lizard has had to evolve a complex method for safely digesting these little ants, venom and all.
Scores of papillae – finger-like projections of flesh – line the backs of their tongues and run all the way down their throats. These papillae squeeze and bind the harvester ants in mucus strands as they’re swallowed, and once they reach the lizard’s oesophagus, the ants are met with more mucus-secreting skin folds that keep them incapacitated all the way down to the stomach. Scientists aren’t exactly sure how it works, but it’s been suggested that once the ant venom reaches the Texas horned lizard’s blood stream, defensive chemicals are added to ensure that the blood is ready for its journey to the head, through the eye sockets and into the face of the enemy.