Some lizards have evolved the remarkable ability to give birth to live young instead of laying eggs. This reproductive strategy, known as viviparity, allows embryos to develop inside the mother’s body, where they are protected from environmental dangers. It represents an advanced adaptation that enhances the survival chances of offspring in challenging habitats.
The process begins when fertilized eggs remain within the mother rather than being deposited in a nest. The developing embryos receive nutrients either from yolk reserves or, in some cases, through a placenta-like connection that facilitates direct nourishment. This internal development continues until the young are fully formed and ready to emerge.
Lizards that give live birth often inhabit cooler or unpredictable environments. In such areas, the soil or temperature may not be suitable for incubating eggs. By keeping the embryos inside, the mother can regulate their temperature through her own movements and body heat, ensuring optimal conditions for development.
This form of reproduction typically results in fewer offspring at a time compared to egg-laying species, but the survival rate of each newborn is usually higher. The young are often born well-developed and capable of independent movement shortly after birth, allowing them to adapt quickly to their surroundings.
Parental care is minimal once the young are born, but the internal gestation period provides them with an early advantage. The mother’s protection during development significantly reduces exposure to predators and environmental hazards, improving the success of the next generation.
Lizards that Give Live Birth
Common Blue-tongued Skink (Tiliqua scincoides)
Native to Australia and New Guinea, these large, docile skinks are live-bearers. They typically give birth to a relatively small litter of 10-25 live young, which are independent from the moment they are born. The babies are encased in a thin embryonic membrane which they immediately break free from.
Solomon Island Prehensile-tailed Skink (Corucia zebrata)
Also known as the Monkey-tailed Skink, this species has the most developed form of viviparity of any lizard. They have a mammalian-like placenta and a gestation period of 6-8 months, one of the longest for any lizard. They typically give birth to a single, very large offspring, which the parents care for extensively.
Jackson’s Chameleon (Trioceros jacksonii)
Native to East Africa but introduced to Hawaii, this chameleon gives birth to live young. The gestation period can last several months, and the female gives birth to 8-30 tiny, independent chameleons. The young are born in a sticky transparent membrane from which they must quickly escape.
Slowworm (Anguis fragilis)
Often mistaken for a snake, the slowworm is a legless lizard native to Europe and Asia. After a gestation period of several months, the female gives birth to an average of 6-12 live young. The babies are born in a thin, transparent egg sac which they rupture within a few hours.
Common European Adder (Vipera berus)
While technically a viper and not a lizard, it’s a classic example of a reptile that gives live birth and is often included in this context. The females incubate the eggs inside their bodies and give birth to a litter of live young, usually in late summer or early fall.
Shingleback Lizard (Tiliqua rugosa)
Also known as the Bobtail Skink or Sleepy Lizard, this Australian species is known for its monogamous pair bonds. They give birth to one or two extremely large live young, which can be nearly half the size of the mother at birth.
Mountain Horned Dragon (Acanthosaura capra)
This arboreal lizard from Southeast Asia is an example of an ovoviviparous species. The eggs are retained inside the female’s body until they are ready to hatch, and she gives birth to live young. This is less common among arboreal (tree-dwelling) lizards.
Gila Monster (Heloderma suspectum)
One of only a few venomous lizards in the world, the Gila Monster of the southwestern United States and northwestern Mexico is an egg-layer. However, its close relative, the Mexican Beaded Lizard (Heloderma horridum), is known to be oviparous, laying eggs. This highlights the diversity even within closely related groups.
Common Wall Lizard (Podarcis muralis)
This small, agile lizard found throughout much of Europe is primarily an egg-layer. However, some populations, particularly those at higher altitudes, have been observed giving birth to live young, demonstrating how environmental pressure can influence reproductive strategy.
Viviparous Lizard (Zootoca vivipara)
As its scientific name implies, this small lizard is a classic example of viviparity. It has the most extensive geographic range of any terrestrial lizard, extending across northern Europe and Asia. Its ability to give live birth is a key factor in its success in these cool climates. Some southern populations of this species, however, have re-evolved egg-laying, making it a fascinating subject for evolutionary study.