Horned lizards, often called “horny toads” due to their squat, flattened bodies, are reptiles found primarily in desert and semi-arid environments across North America. Their distinctive appearance, characterized by a crown of horns on their heads and spiny bodies, offers camouflage and defense in their natural habitat. These lizards have evolved specialized adaptations for a diet that sets them apart from most other lizard species.
Primary Food Source: Ants
The diet of horned lizards consists primarily of ants, making them ant specialists. While some species consume almost nothing else, others supplement their diet with other insects. Ants are a reliable food source because they occur in clumped spatial distributions, forming a concentrated supply.
Horned lizards possess a large stomach for their body size to accommodate the quantities of ants. For example, the stomach of a desert horned lizard (Phrynosoma platyrhinos) can account for about 13 percent of its total body weight. This adaptation is necessary because ants are small and contain indigestible chitin, requiring the lizard to consume many individuals. Harvester ants are a preferred food source for some horned lizard species, such as the regal horned lizard (Phrynosoma solare), making up to 90 percent of their diet. Horned lizards have developed a resistance to ant venom, allowing them to consume these insects despite their defensive capabilities.
Other Dietary Items
While ants are the dominant food source, horned lizards occasionally consume other small invertebrates. These supplementary items include beetles, grasshoppers, and spiders. Such items form a minor component of their diet, often consumed when ants are less abundant or by less specialized horned lizard species.
These insects provide dietary variation, though the specialized morphology of horned lizards, including their blunt, non-cusped teeth and reduced jaw musculature, is primarily adapted for an ant-based diet. This reinforces their niche as ant predators.
Foraging and Feeding Habits
Horned lizards primarily employ a “sit-and-wait” or ambush predation strategy. They often position themselves in open areas near ant nests, waiting for ants. Their camouflaged appearance, which closely matches the soil, helps them blend into their surroundings and avoid detection by both prey and predators.
When an ant or other small insect passes by, the lizard swiftly captures it with a flick of its sticky tongue and swallows it whole. Horned lizards are reluctant to move, which enhances their camouflage. This behavior can also lead to more variable body temperatures compared to other lizard species, as they may remain still for extended periods.