Lizards, as opportunistic insectivores, encounter a vast array of invertebrates, and the millipede is a common presence in many ecosystems. Whether a lizard chooses to consume a millipede is a complex question that often comes down to an evolutionary arms race between predator and prey. The answer is a cautious “sometimes,” heavily influenced by the millipede’s potent arsenal of chemical and physical defenses. This delicate balance dictates which species of lizard can safely turn this slow-moving arthropod into a meal.
The Direct Answer: Predation Habits
Millipedes are not generally a preferred food source for most lizards due to the risks involved in their consumption. Generalist lizard species may occasionally eat a millipede, but they typically avoid them when less-defended prey is available. This interaction often occurs during times of scarcity when a lizard’s usual diet of spiders, crickets, or beetles is hard to find.
The size and species of the millipede also play a significant role in the lizard’s decision-making process. Smaller, soft-bodied millipedes are more likely to be consumed by a wider range of lizard species, as their defenses are easier to overcome. Conversely, large, heavily armored millipedes present a double deterrent: a tough exterior coupled with a substantial dose of defensive secretions.
Millipede Defense Mechanisms
Many lizards bypass millipedes due to specialized secretory glands running along the body segments. When threatened, a millipede can exude a noxious cocktail of chemicals from these ozopores, designed to deter a predator. The composition varies by species, but it often includes foul-tasting compounds like quinones, which act as irritants and repellents.
Some millipede species produce toxic substances, such as hydrogen cyanide, which is a lethal deterrent to smaller or less-tolerant predators. This chemical defense is often advertised by aposematic or warning coloration on the millipede’s body, signaling its unpalatability to experienced lizard predators. A lizard that encounters this strong, unpleasant taste or odor learns to associate the warning colors with a negative dining experience.
The millipede’s physical defense complements its chemical warfare, providing a robust layer of protection. They possess a hard, calcified exoskeleton, or cuticle, which acts as a physical barrier against a lizard’s jaws. When attacked, many species employ a behavior called volvation, where they tightly coil their bodies into a spiral. This posture protects their vulnerable underside and legs, exposing only the tough, chemically-defended external plates.
Specialized Lizard Predators
Despite these formidable defenses, some lizards have developed specific strategies or physiological tolerances to include millipedes in their diet. Certain skinks, such as the blue-tongue skink, are known to have a higher tolerance for the millipede’s defensive chemicals. Their foraging habits and general omnivorous nature make them more likely to tackle challenging prey like arthropods with strong defenses.
Monitor lizards and some specialized insectivorous species have been observed using behavioral tactics to mitigate the chemical threat. A lizard may repeatedly rub the millipede against the ground before consumption, draining or scraping off the initial burst of noxious secretion. This action reduces the concentration of chemicals ingested, making the millipede safer to eat.
Specialized predators may rapidly swallow the prey to bypass the worst of the chemical release. This demonstrates an evolutionary adaptation where the reward of a protein-rich meal outweighs the risk of temporary discomfort or mild poisoning. The ability to safely consume millipedes provides a dietary advantage in environments where other food sources are limited.