The Thorny Devil (Moloch horridus) is an Australian lizard instantly recognizable by the dense, conical spines covering its body, which provide both camouflage and defense in the arid and semi-arid regions it inhabits. This slow-moving reptile grows to about 8 inches in length and is an extreme dietary specialist. Its entire existence is predicated on a single food source, making it a classic example of hyper-specialization in the animal kingdom. This dependence dictates its behavior, physical form, and survival strategies in the harsh desert environment.
The Thorny Devil’s Exclusive Diet
The Thorny Devil is an obligate myrmecophage, meaning its diet consists exclusively of ants. This specialization focuses primarily on small, black ants from the genus Iridomyrmex, sometimes called meat ants, but also includes other genera such as Camponotus and Crematogaster. Because ants are individually low in caloric content and contain a large amount of indigestible chitin, the lizard must consume them in enormous quantities to meet its daily energy requirements.
A single Thorny Devil is estimated to consume between 750 and 5,000 individual ants in a single day of feeding. This high volume is required to extract sufficient protein and nutrients from the low-energy prey items. The lizard possesses a large stomach specifically adapted to accommodate the sheer mass of ants required for survival.
Specialized Feeding Adaptations
The lizard employs a “sit-and-wait” foraging strategy, remaining motionless near established ant trails until a sufficient number of prey pass by. This behavior minimizes energy expenditure while maximizing the density of available food. The Thorny Devil then uses its short, sticky tongue to rapidly lap up the passing ants.
The physical mechanism for consumption is highly efficient, with the lizard capable of ingesting ants at a rate of up to 45 ants per minute during peak feeding. Its mouth structure is specifically adapted for this task. The jaw is small, and the teeth are modified not for chewing, but for processing the hard, chitinous exoskeletons of the ants.
Habitat and Dietary Necessity
The Thorny Devil’s specialized diet is directly linked to the scarcity of resources in its arid and semi-arid Australian habitat, characterized by sandy soils and sparse vegetation. In this environment, ants are a relatively reliable, albeit low-energy, food source. The lizard’s reliance on this high-volume, low-calorie diet is supported by a correspondingly slow metabolic rate and characteristically slow, jerky movement.
Conserving energy is necessary in this harsh environment, and the lizard’s low-energy lifestyle allows it to survive on the limited nutritional value provided by the ants. This energy balance is reflected in the Thorny Devil’s unusually long lifespan, which can extend up to 20 years in the wild.