Lizards, a diverse group of reptiles with over 7,000 species, exhibit a wide range of feeding habits. Their diets can be broadly classified into insectivorous, carnivorous, omnivorous, and herbivorous, each with its own specific requirements. Understanding these dietary needs is crucial for maintaining the health and well-being of lizards, especially those kept as pets.
Dietary Classifications of Lizards
The feeding patterns of lizards are extremely diverse. Lizards may be:
- Insectivorous: These lizards primarily consume insects. Examples include day and leopard geckos, whiptail lizards, anoles, and chameleons.
- Carnivorous: These lizards primarily eat other animals. Examples include varanids (such as monitor lizards), Gila monsters, and Mexican beaded lizards.
- Omnivorous: These lizards consume a combination of insects, other animals, and plant matter. Many iguanid and agamid species fall into this category.
- Herbivorous: These lizards primarily eat plants. Examples include iguanid species and prehensile-tailed skinks.
Nutritional Needs and Supplementation
Regardless of their dietary classification, all lizards need fresh water daily. Most also need supplemental nutrients, such as calcium and vitamin D3, plus a multivitamin. The frequency of supplementation depends on their species, age, and breeding status. Typically, supplemental vitamins and minerals are provided as a powder dusted in small amounts on insects or produce, depending on the lizard’s diet. For most commonly kept captive lizards, calcium without added vitamin D3 should be sprinkled on food every other day, alternating with calcium containing vitamin D3 on the days in between. In addition, a multivitamin should be offered on food once a week.
Feeding Insectivorous Lizards
Insectivorous lizards in captivity are usually fed diets of mealworm larvae or crickets. Because calcium concentrations in these, and in most insects, are extremely low (0.03-0.3% calcium with 0.8-0.9% phosphorus), the inverse calcium:phosphorus ratio must be corrected before the insects are fed to lizards. A diet with a balanced vitamin and mineral mixture and containing 12% calcium as calcium carbonate can be fed to crickets or mealworm larvae 3 days before the insect is fed to the lizard. However, this diet should not be used to maintain a cricket colony. Within 2 days after feeding the high-calcium diet, the gut of the insect is filled with calcium, raising the calcium concentration of the insect to approximately 0.8-0.9% and resulting in a calcium:phosphorus ratio of approximately 1.2:1-a ratio much more appropriate for a feeding reptile. A satisfactory high-calcium diet for crickets can be inexpensively made by using 29% wheat middlings, 10% corn meal, 40% ground dry cat or dog food, and 21% ground oyster shell or calcium carbonate. Larger insectivorous lizards may also consume mouse pups and earthworms. Vitamin A deficiency can occur in some species (eg, carnivorous tortoises and some lizards); therefore, vitamin A should be supplemented as needed.
Gut Loading Insects
To ensure a complete diet for your lizard friend, it’s necessary to supplement oral calcium and vitamin powders. These can be added to your insect’s diet by “gut loading” them prior to feeding them to your reptile. Some nutrient-specific diets are best fed for a few days before feeding to your lizard, while others can be dusted with a supplement immediately before feeding it to your lizard. Either way, your lizard will get those extra nutrients upon eating the prey. Make sure to talk to your veterinarian about the specifics of feeding these supplements to your lizard. Many pet parents find a schedule helpful to remember which supplement to give and when, as over-supplementation can be just as harmful as under-supplementation.
Read also: Diet and Feeding: Armadillo Girdled Lizard
Feeding Carnivorous Lizards
Carnivorous lizards may be offered mouse or rat pups, adult mice and rats, chickens, and eggs. The size of prey should be appropriate for the lizard species. Large carnivorous species should be fed once or twice a week.
Feeding Omnivorous Lizards
Omnivorous lizards are usually fed a combination of foods, including insects, vertebrate prey, and a chopped vegetable mixture. Most lizards should be fed daily (juveniles and small species) or at least every other day.
Feeding Herbivorous Lizards
Herbivorous lizards are adapted to ferment plant fiber in enlarged hindguts. The microbes in the cecum and colon digest plant fiber that the lizard could not otherwise use. As with tortoises, herbivorous lizards should be fed plant-based diets to assure healthy gut function. The use of insects, vertebrate prey, or diets high in fruits is not advised, because these feeds are low in fiber and are inappropriate for herbivores. All fruit items should be fed to lizards in limited amounts; feeding too many fruits to even herbivorous reptiles can lead to nutritional disorders.
Common Pet Lizards and Their Diets
Perhaps the most commonly kept lizards today include bearded dragons, leopard geckos, and chameleons.
Bearded Dragons
Bearded dragons are omnivores that should be a fed a mixture of fresh (rather than less-nutritious frozen or canned) produce plus live insects daily. They can have vegetables such as leafy greens, squash, carrots, peppers, broccoli, string beans, sweet potatoes, pumpkin, celery, cucumbers, and asparagus, with smaller amounts of fruit such as bananas, apples, pears, peaches, melon, plums, apricots, nectarines, watermelon, grapes, papaya, pineapple, and berries. Onions and garlic should be avoided. Insects they can be fed include mealworms, crickets, Dubia roaches, butterworms, hornworms, Phoenix worms, earthworms, silkworms, superworms, and waxworms (which should be fed sparingly, as they are fatty). All of these worms are available from pet stores; insects found outside or in homes should not be fed, as they may contain pesticides or other chemicals unhealthy for lizards. Just as fresh produce is more nutritious than frozen or canned, live insects are more nutritious than dead ones, plus the movement of the insects stimulates the lizard’s instinctual hunting behavior. All insects should be gut-loaded (fed with fortified food) so that they are nutritious for the lizard, and the lizard should be offered only enough insects that it will eat, so that left over insects trapped in the lizard’s enclosure don’t start chewing on the lizard.
Read also: Feeding Frilled Lizards
Leopard Geckos
Leopard geckos are carnivores, eating only insects and no vegetables. Young geckos eat daily, while some large adults may only need to eat every other day, depending on their overall health and breeding activity. Most geckos eat predominantly mealworms and crickets, but depending on their size, they can also be fed a variety of the other worms listed above. Just as for bearded dragons, insects should be gut-loaded and only offered in numbers that the lizard will consume so that they don’t get trapped in the lizard’s tank and gnaw on the animal. Be careful not to over feed the gecko, as they tend to overeat and get fat. Healthy geckos will store fat in their tails which should be plump (but not wider than their bodies), not thin and pencil-like. However, overweight geckos will develop a stomach paunch and often have fat deposited along their legs and arms, as well. Ideally, geckos should not be fed more insects than they will eat in a 20-minute period. Be sure, too, not to feed insects too large for the gecko, or they will not be able to eat them.
Chameleons
Chameleons are more difficult to feed (and in general, to keep overall) than other lizards. However, their popularity has increased in recent years. Most chameleons are carnivores, eating a variety of insects (see list above) plus wingless fruit flies; however, veiled chameleons will also eat vegetables such as mustard, dandelion and collard greens. Juvenile chameleons should be fed every day, while adults can be fed every day to every other day, depending on their body weight, breeding status and overall health. Insects should be offered one or two at a time until the chameleon no longer wants to eat. Insects should be dusted with mineral and vitamin supplements, as described above. Chameleons will thrust out their very (up to several inches) long tongues to catch and eat insects one at a time. Another unique feature of chameleons is that they will not drink standing water but drink it dripping off of plants in their enclosures.
Importance of Temperature
Regardless of species, reptiles must be kept within their preferred optimal temperature zones, which vary by species, in order to digest food properly. Lizards, and reptiles in general, are ectotherms that depend on outside heat sources to maintain their body temperatures for optimal digestion and immune system function. Therefore, to keep your lizard healthy, it’s critical to understand not only its optimal diet, but also its optimal temperature range, so that it can process the nutritious food you offer.
Commercial Reptile Foods
There are many commercial reptile foods in-including pellet form on the market for lizards. Mazuri, Repashy, and Fluker's are often great choices when looking to supplement your lizard’s diet. Before offering your lizard these foods, though, it’s important to properly prepare them-just as you would for yourself.
Lizards as a Food Source for Humans
Lizards are considered a delicacy in many parts of the world. The green iguana is one type people commonly eat. In general, lizards are safe to eat if you heat them thoroughly during cooking. Although they may contain disease-causing bacteria, such as Salmonella, E. coli, Campylobacter, and S. aureus, heat kills these bacteria during the cooking process. Lizards like the green iguana are high in protein, low in calories, and high in nutrients, including zinc and iron. Studies have found that consuming these nutrients is linked to health benefits, such as improved immunity and recovery.
Read also: The Hoxsey Diet
Safety Considerations When Consuming Lizards
In general, lizards are safe to eat if cooked thoroughly. There are not many official guidelines on temperature for cooking reptile meat, but FoodSafety.gov recommends cooking poultry until its internal temperature reaches 165°F (74°C). If you purchase lizard meat from an exotic butcher, ask them for guidance on safe handling, cooking methods, and temperature. If not cooked enough, lizards and other reptiles can pose serious health concerns. For starters, lizards may carry various disease-causing bacteria, including Salmonella, Escherichia coli (E. coli), Campylobacter, and Staphylococcus aureus (S. aureus). These bacteria can cause a foodborne illness, or food poisoning. Common signs of food poisoning include nausea, vomiting, and diarrhea. These symptoms may occur within 30 minutes to several days after consuming the meat. These types of bacteria can also be present in more common meats, like chicken. However, lizards and other reptiles are more likely to carry them, along with a variety of other disease-causing bacteria. Additionally, hunting and killing wild lizards yourself has more health risks than purchasing lizard meat from an exotic butcher. Not only are wild lizards more likely to carry harmful bacteria, but they have sharp teeth and claws that may cause harm by spreading germs and other toxic substances from their mouth to a wound. The same cautions also apply to handling lizards. Lizards may carry various disease-causing bacteria, such as Salmonella, and can spread them to humans by contact. If you are handling a live or recently killed lizard, make sure to wash your hands thoroughly immediately afterward - even if the lizard appears to be healthy and clean. Washing your hands can lower the risk of developing an infection. If a lizard bites you, wash the wound thoroughly with soapy water. If the lizard appears to be sick, or if the wound seems serious or inflamed, seek medical attention immediately.
Nutritional Value of Lizard Meat
Just like other types of meat, lizards are packed with nutrients that may offer health benefits. However, it’s important to note that there is little research available on the health benefits of eating lizards. That is why the following possible health benefits are based on studies of the nutrients found in lizards rather than studies on consuming lizards. Lizards are high in various nutrients that are important for your health. For example, a 3.5-ounce (100-gram) serving of green iguana meat contains:
- Calories: 119
- Protein: 20.8 grams
- Fat: 3.5 grams
- Carbs: 1.2 grams
- Zinc: 23% of the Daily Value (DV)
- Iron: 11% of the DV
- Potassium: 6% of the DV
- Magnesium: 5% of the DV
Green iguana meat also contains small amounts of calcium, phosphorus, copper, and manganese. Keep in mind that this nutritional information is specific for green iguana meat, as the green iguana is one of the most commonly eaten lizards in the world. The nutritional content of other lizards may vary.