The terms gecko and lizard can sometimes be used to refer to the same thing. And this is not always inaccurate. Technically, a gecko is a type of lizard and one of the most common types too. However, the term lizard can mean much more. There are also several other differences as demonstrated here.
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Classification
Geckos and lizards share much of the same classification. They are both a part of the Animalia kingdom, Chordata phylum, Tetrapoda Superclass, Reptilia class, Squamata Order and Lacertilia suborder. This explains why they are so similar. However, at this point there is a distinction between the two. Within the Lacertilia suborder, there are 5 additional groups including the one that geckos belong to, the Gekkota group, or infraorder. Along with Gekkota, the other infraorders are Anguimorpha, Iguania, Lacertoidea, and Scincomorpha.[i]
For this reason, a gecko is always considered a lizard, while a lizard may not always be a gecko as lizards refer to four other groups of similar species. Among other species of lizards, there are many others that are commonly found. Some examples are the iguanas and their families which would also have chameleons, agamid lizards, helmet lizards and spiny-tail iguanas, among others. Within the Scincomorpha infraorder are such species as the skinks, whiptails, spectacled lizards, night lizards, plated lizards and spinytail lizards. Glass lizards, American legless lizards and know-scaled lizards are part of the infraorder Diplogloss. And finally, the infraorder Platynota contains monitor lizards, Gila monsters, bearded lizards and marine lizards.[ii]
The infraorder that contains geckos, Gekkota, also has 7 genera within it. The family Gekkonidae contains all gecko species. The family Pygopodidae has legless lizards and the family Diblodactylidae has blind lizards. There are also the Carphodactylidae, Sphaerodactylidae, Phyllodactylidae, and Eublepharidae families. So even within the gecko’s suborder there are further distinctions between the other lizards and the gecko itself.[iii]
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Regions where both live
Lizards are found all over the world. The populate every continent except for Antarctica and are also found on most island chains within the world’s oceans. The suborder Iguania alone is found in Africa, southern Asia, Australia, North and South America and the islands of the west Pacific.[iv] Since there are a wider variety of animals that would be considered lizards than there are geckos, their geographical range is larger as well.
Geckos are typically found in warm climates throughout the world, including areas in the southern United States, northwest Mexico, southeast Asia, North, Central and South America as well as the Caribbean islands and the Mediterranean area from southern France to north Africa.[v]
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Method of birthing
Most lizards lay eggs meaning they are oviparous. However, with some lizard species, they will give birth after they have hatched the eggs inside their body. And still with other lizards, they will give birth to live young. If they are egg-laying, the lizards will place their eggs in nests.[vi] Lizards are also capable of parthenogenesis in squamata, which is asexual reproduction. This type of reproduction is found in approximately 50 species and it occurs with there is a widespread absence of males to impregnate the females.[vii]
The reproduction habits of geckos can vary. Most of them are egg-laying and will lay between four and five pairs of eggs during their mating season between May and August. The egg pairs will typically occur between two and four weeks of each other.[viii]
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Diet
Most geckos feed on other live creatures such as insets, moths, beetles, butterflies, crickets, cockroaches and mosquitos. Larger species, such as the Caledonian gecko will hunt other young lizards, mice and even small birds. Geckos that are kept as pets, such as the leopard gecko, will typically eat fruits and insects.[ix] While this would be a typical diet for most gecko species, the crested gecko can feed entirely on fruit to survive.[x]
Lizards, on the other hand, usually have a diet with a wider variety. They will eat fruits and other vegetation, insects, small tetrapods such as frogs and mice, carrion and with large predator lizards, they may even hunt large prey such as deer. Lizards that are kept as pets, such as iguanas, bearded dragons, tegus and monitor lizards[xi] will typically feed on live crickets or worms.[xii]
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Physical Appearance and traits
Lizards and geckos do have many similarities in their appearance. Both of the animals have four legs and are cold blooded and both of them have species that are able to change color to blend in with their environment. However, there are still differences. Lizards usually have dry and scaly skin while a gecko will have thin skin with small bumps on it. This is one reason it is usually found in more temperate climates. Lizards also have external ears and moveable eyelids while geckos only have a transparent membrane over their eyes that they lick clean.[xiii]
Geckos also have the unique ability to climb vertical surfaces due to specialized pads on their toes, which is something that lizards are unable to do. Lizards actually have clawed feet. Geckos can emit a foul-smelling discharge and feces on any predators while lizards to not exhibit this behavior. The lifespan of both animal is also quite different. Lizards, on average, will live for one to three years, but there are some that can survive decades. The average lifespan of a gecko is five to seven years.[xiv]