Lizards are a diverse group of reptiles found across nearly every continent, exhibiting a wide range of sizes, shapes, and habitats. Their varied diets reflect this diversity, as each species has evolved unique feeding strategies to thrive in its environment. Understanding what lizards eat involves recognizing their natural diets, influenced by their biological makeup and food availability.
Main Dietary Classifications
Lizard diets fall into three main categories: carnivorous, herbivorous, and omnivorous. Carnivorous lizards primarily consume other animals, from insects to small vertebrates. Many geckos and chameleons are insectivores, eating insects and other invertebrates. Larger carnivorous species, like monitor lizards and Gila monsters, may prey on a wider variety of animals.
Herbivorous lizards subsist mainly on plant matter. Green iguanas and Uromastyx species, for example, eat leaves, flowers, and fruits. Only about 2% of lizard species are strictly herbivorous. Omnivorous lizards have a varied diet, incorporating both plant and animal matter. Bearded dragons and blue-tongued skinks are common omnivores, consuming a mix of insects, vegetables, and fruits.
Common Food Sources
Insects and other invertebrates are common food sources for insectivorous, carnivorous, and omnivorous lizards. Common feeder insects include crickets, mealworms, Dubia roaches, superworms, waxworms, and hornworms. These provide essential protein and nutrients. Larger carnivorous lizards, such as monitors, also prey on small vertebrates like rodents, fish, birds, other reptiles, and eggs.
Herbivorous and omnivorous lizards incorporate plant-based foods. Leafy greens like collard greens, dandelion greens, mustard greens, and kale are common staples. Other suitable vegetables include yellow squash, turnip greens, bell peppers, carrots, and sweet potatoes. Fruits, such as apples, berries, honeydew melon, strawberries, and grapes, can be offered in moderation due to their higher sugar content. These plant foods provide fiber, vitamins, and antioxidants.
Factors Influencing Diet
A lizard’s diet is influenced by several factors. Species-specific adaptations play a role, as lizards have evolved specialized dentition and digestive systems suited to their natural food sources. For example, a gecko’s insect diet differs from an iguana’s plant-based diet.
A lizard’s age and size also affect its dietary needs. Younger, growing lizards often require more protein for rapid development. Juveniles may consume more insects than adults, gradually transitioning to a different diet as they mature. The availability of food sources in their habitat dictates what a lizard can eat. Seasonal changes can also lead to shifts in wild diets as certain prey or plant items become more or less available.
Nutritional Requirements and Foods to Avoid
A balanced diet for lizards requires attention to nutritional needs and awareness of harmful foods. Calcium and vitamin D3 are important for bone health and preventing metabolic bone disease in captive lizards. These nutrients are often supplied by dusting feeder insects or plant matter with calcium and vitamin supplements, as many captive lizards may not receive sufficient natural UVB exposure. “Gut loading,” feeding nutritious foods to feeder insects before offering them, enhances their nutritional value.
Hydration is also important for a lizard’s well-being. Many lizards drink water directly from bowls or by licking dew droplets, while others obtain moisture primarily from their food. Some species absorb water through their skin. Foods to avoid include toxic items such as fireflies, avocados, citrus fruits, onions, and garlic. Wild-caught insects should be avoided due to the risk of pesticide exposure or parasites. Processed human foods, like bread or sugary snacks, are unsuitable as they lack essential nutrients and are difficult for lizards to digest.