08-05-2025
Nature's most bizarre: This lizard can shoot toxic blood from its eyes to avoid being attacked and eaten by predators
When it comes to bizarre defense mechanisms in the animal kingdom, few creatures can match the North American horned lizard. These small reptiles, often called 'horny toads' due to their squat, flat shape and short snouts that give them an amphibian-like appearance, possess an arsenal of peculiar abilities that make them truly extraordinary.
While the Komodo dragon might claim fame as the largest and most venomous lizard, the horned lizard proves that 'power isn't always about size,' according to Discover Wildlife. At just 9 centimeters in length, these diminutive creatures have evolved remarkable strategies to ward off predators many times their size.
Nature's most unusual defense mechanism
Their most spectacular defense is the ability to shoot blood from their eyes — a behaviour known scientifically as autohaemorrhaging. When threatened, these lizards can direct a stream of blood with remarkable precision 'to a distance of up to nine times their body length,' as reported by Discover Wildlife. Live Science elaborates on the mechanics: 'They do this by restricting the blood flow leaving their heads, which increases blood pressure and causes tiny blood vessels to burst around the eyes.'
This blood isn't just for show. It contains toxic chemicals that make it particularly effective against certain predators. According to Live Science, 'While it doesn't appear to deter birds, the blood does affect canines like dogs (Canis familiaris), coyotes (Canis latrans) and foxes (Vulpes), which shake their heads to get rid of it. The lizards seem to recognise this and are more likely to use it on dogs than on other predators.'
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How is the blood laced with toxins?
The toxicity of their blood appears to be derived from their unusual diet. These lizards primarily feed on venomous harvester ants, seemingly immune to the insects' venom. Live Science explains, 'Short-horned lizards aren't affected by the venom of the harvester ants they feed on because a chemical in their blood plasma neutralises it. They also produce large amounts of mucus to immobilise the insects, enabling the lizards to swallow them without getting hurt by the venom.'
Other mechanisms for protection from predators
Remarkably, the horned lizard doesn't rely solely on its blood-squirting ability for protection. Its defensive repertoire includes several other adaptations. Their mottled skin provides excellent camouflage, helping them blend into their surroundings and avoid detection. Their bodies are covered in sharp spines, including two prominent head spikes that can deter would-be predators. As Live Science describes, 'If a predator attempts to bite them, the feisty lizards bow their head, exposing the horns to the predator's mouth.'
Perhaps most impressive is their ability to dramatically change their size when threatened. 'The lizards can also inflate themselves to twice their normal size when attacked,' notes Live Science. 'Not only does this make them look more intimidating, it can cause predators trying to swallow them to choke.'
Around eight species of horned lizards are believed to possess this extraordinary blood-squirting ability, according to Live Science. While it may seem grotesque to human sensibilities, this defense mechanism represents one of nature's most ingenious adaptations, allowing these small reptiles to survive in environments filled with much larger predators.
