Lizards are the largest, most diverse group of Reptilia on earth, occupying niches on every continent except for Antarctica. These scaley, cold-blooded creatures have evolved to feed on a range of different food sources, from small mammals to birds, eggs, vegetation, and even other lizards!
Many lizard species are insectivorous, eating ants amongst many other insects. Small lizards, like geckos and skinks, eat many ants and termites, as well as their larvae. Some species, like horned lizards from the American West and thorny devils from Australia, eat a diet of ants exclusively.
The common lizards that we see in and around our homes and gardens are mainly insectivores, eating some ants along with crickets, grasshoppers, flies, and cockroaches. Pet lizard species, like leopard geckos, are also insectivorous but cannot be fed ants because they are not adapted to eating them. Ant-eating lizards have special adaptations that protect them from ants. In large numbers, ants can easily kill a lizard.
What Do Lizards Eat in the Wild?
Different lizards eat a variety of different diets. Most species are insectivores or omnivores, feeding on a range of bugs and vegetation.
Some lizards, like green iguanas, are exclusively herbivores, while others, like the giant Komodo dragon, are carnivores, feeding on mammals, birds, and even other lizards!
Geckos, fence lizards, and skinks that live in our gardens and sometimes come into our homes are mainly insectivores. These lizards are beneficial to us because they eat insect pests like roaches and ants.
Ants are not usually a top menu item for most lizards because, individually, they are too small to be nutritious. They have a hard, chitinous exoskeleton that lizards cannot digest. It is far more energy-efficient for lizards to pursue more substantial, nutritious insects.
Ants are Hazardous Prey
Ants are tiny and have therefore had to develop adaptations to protect them from the many, many larger animals that could predate on them.
Most ant species produce a venom called formic acid. Wood ants can squirt formic acid at their predators, irritating their eyes to deter them. Many insectivorous lizards avoid eating ants because they taste bad due to their venom.
Some species of ants, like harvester ants, have powerful jaws, or mandibles, and stingers on their abdomens that inject a paralyzing venom.
Ants’ greatest superpower is their ability to work together in large numbers. Most animals in the wild avoid ants altogether because an army of ants can easily overwhelm and kill larger animals by crawling all over them, stinging and biting.
Species of Lizards that Eat Ants
Even though ants are not the most convenient or nutritious prey items, some species of lizards feed almost exclusively on them. These lizards have evolved specialized adaptations to overcome ants’ defenses.
Fence lizards
In 2018 a study that was published in the Canadian Journal of Zoology investigated the diet of Eastern Fence Lizards (Sceloporus undulatus). It found that ants make up 80% of juvenile lizards’ diets and account for 50% of adult lizards’ diets.
Another important finding this research made was that fence lizards eat native ants, as well as invasive ant species, like fire ants. Fire ants are highly venomous, but the fence lizards seem to have built up a tolerance to their venom.
Horned lizards
Phrynosoma solare, a species of horned lizard native to the Sonoran Desert, is a specialist ant-eater. These lizards’ diet consists of 90% harvester ants.
The horned lizards have a sticky tongue they use to grab the ants rather than using their jaws. They can run very quickly to escape a swarm of ants if necessary.
The horned lizards are not affected by the ants’ venom. Their bodies are adapted to a diet of ants – their stomach is much larger as a percentage of their body mass compared to other lizards. This is so that they can eat the huge number of ants required to meet their nutritional needs.
Why Do Horned Lizards Prefer Harvester Ants?
Harvester ants mainly feed on seeds, mushrooms, vegetables, and sweet fruits. So, they tend to have a sweeter taste, making them more enjoyable for horned lizards.
Harvester ants tend to bite, and like the fire ants, they have potent venom, but unlike the fire ants’ venom, the harvester ants’ venom has little effect on the horned lizard.
Thorny devils
Moloch horridus, or thorny devil, is a unique lizard native to the deserts of Australia. Perfectly camouflaged to match their rugged landscape and with sharp spines to ward off predators, these little devils feed on nothing but ants.
They can eat around 3000 ants per day! With a long, adhesive tongue that shoots out their mouth, they catch the ants, and they have specially adapted teeth to chew the ants and digest them quickly.
Like horned lizards, thorny devils have an enlarged stomach so that they can eat as many ants as possible to meet their energetic needs.
Can Pet Lizards be Fed Ants?
Leopard geckos, agamas, and house lizards are popular pets. It is fascinating to watch their behavior up-close. Many people that keep pet lizards catch insects around their house and garden to feed them. It is important to know which insects your pet lizard would naturally eat.
Lizards are fussy eaters and will not eat insects that are already dead. Therefore, the insects you catch for them must be kept alive. The process of catching large numbers of ants regularly is impractical in itself, but there is another reason that it is not recommended to feed a captive lizard live ants.
Pet lizards should never be fed ants because they do not have the necessary adaptations to eat them. The ants could potentially crawl all over your lizard, and without anywhere to escape, the lizard could be stung and bitten to death by the ants.
Conclusion
There are a wide variety of different lizard species that eat a range of different diets. Some are carnivorous, omnivorous, and herbivorous, while others are insectivorous.
The vast majority of insectivorous lizards do not feed on ants as a primary prey source. They are much too small, and their hard exoskeleton is difficult to digest. There are far more nutritious, substantial insects for lizards to eat.
Ants are also difficult to predate on because of their strong mandibles, venomous sting, and their strength in numbers. They contain formic acid, which gives them a bad taste. The lizard species that feed on ants have special adaptations to overcome the ants’ defenses.
Horned lizards, thorny devils, and Eastern fence lizards eat a diet of mainly ants. These lizards have enlarged stomachs so that they can eat as many ants as possible to meet their caloric needs. They have also developed a tolerance to ant venom.
Pet lizards in captivity should not be fed live ants because they can be a danger to the lizard. With nowhere to escape, ants can crawl all over a lizard and sting them to death.
Resources
https://www.everythingreptiles.com/what-do-lizards-eat/
http://blog.cdnsciencepub.com/juvenile-lizards-consume-invasive-fire-ants/
https://www.desertmuseum.org/books/nhsd_horned_lizard.php
http://bioweb.uwlax.edu/bio203/s2014/palmer_tayl/adaptation.htm
