The thorny devil, Moloch horridus, is a reptile known for its unique appearance and adaptations to the Australian desert. This small lizard, also called the mountain devil or thorny dragon, is covered in spiky cones and shields, giving it a distinctive look. Despite its intimidating exterior, the thorny devil is harmless and suited to survive in the arid scrublands and sandplains of central and western Australia.
The Exclusive Diet
The thorny devil’s diet consists almost entirely of ants. This makes them myrmecophagous, meaning “ant-eating” organisms. They primarily target ant species, including Iridomyrmex and other genera. This narrow dietary focus is possible because these ant species are abundant in their desert habitat.
To sustain themselves, thorny devils consume a large number of ants daily. An individual can eat anywhere from 600 to 3,000 ants in a single day. This high consumption rate is necessary because ants offer low nutritional value. Thorny devils compensate for this by having enlarged stomachs, which allow them to process the vast quantities of prey for sufficient nutrients.
Unique Feeding Strategies
The thorny devil employs specific behaviors and physical adaptations to consume its diet. They are known for their slow, deliberate movements, often freezing and rocking, which helps them blend into their surroundings and avoid predators. When foraging, they patiently position themselves near active ant trails, especially during the cooler parts of the day when ants are most active.
Once an ant trail is located, the thorny devil uses its vision to spot individual ants. It then extends a short, sticky tongue with speed and accuracy to flick up ants one by one. Their small, peg-like teeth are adapted to crush the hard exoskeletons of their ant prey. This efficient method allows them to consume ants rapidly, sometimes as quickly as one ant per second, to meet their dietary needs.
Water Collection and Survival
Beyond their unique diet, thorny devils possess a mechanism for collecting water, important for survival in their arid habitat. Their skin is covered in a network of microscopic channels between their scales. These channels act like a plumbing system, using capillary action to draw water from various sources directly to the lizard’s mouth.
This allows them to collect moisture from dew that condenses on their bodies in the early morning, from rainfall, or even from damp sand. When the thorny devil comes into contact with water, such as stepping in a puddle or pressing against moist sand, the grooves between its scales absorb the water, and it is passively transported across its body to the corners of its mouth for ingestion. This adaptation enables the thorny devil to hydrate without needing to drink directly from standing water, a significant advantage in its dry habitat.