A baby chameleon meets us head on…
Given that there are nearly 5,000 identified species, it’s hardly surprising that lizards are pretty diverse creatures. When it comes to reproduction, for example, some species actually give birth to live young! It’s true that the majority of lizards lay eggs, known in biological terms as ‘oviparous’. Other species, however, seem to give birth to live babies but are, in fact, ovoviviparous. This means they produce eggs that hatch inside their bodies, so their offspring is not attached to a placenta when delivered. What’s more, some lizard species even give birth using the placental method common to mammals.
Got you wrapped round my finger…
Let’s take a look at ovoviviparous lizards first. When the time for hatching arrives, the shells of the eggs held inside the mother’s abdomen will have become little more than a thin membrane encasing the tiny lizards. When the babies emerge from Mom, the membrane has often already broken, causing it to look like a normal live birth.
Four baby blue-tongue skinks.
Actual placental (or viviparous) births are extremely rare among lizards but are known to occur in certain skinks from the Solomon Islands. The monkey-tailed skink, for example, provides its young with a placenta, and only gives birth to a few offspring each year. Blue-tongued skinks are also known for giving viviparous birth.
A chameleon in the hand is worth…
The babies of the viviparous skinks tend to be bigger and more developed than those of other lizards, but in general baby lizards can fend for themselves. In the case of the oviparous lizards, the mother lays her eggs (sometimes in a hole she has dug) and then simply leaves them — her job is done. Yet the little ones still have all they need to develop fully and hatch.
A baby bearded dragon on a woman’s hand.
While most lizard eggs have a leathery exterior, some are made of much tougher stuff. Those of the tokay gecko, for instance, harden while stuck to a surface. The sandstone gecko, meanwhile, lays her eggs in fissures, where the shells need to be tough to protect against their rocky environment. Interestingly, the Nile monitor lizard lays her clutch inside termite mounds because the warmth generated by the industrious insects helps incubate the eggs!
Face to face with a little African chameleon.
Even though mother lizards will have long gone by the time her eggs hatch, some baby lizards do need a little help getting out of their shells. In order to help them escape, these little reptiles are born with an ‘egg tooth,’ a sharp, beak-like protuberance that falls off after it has served its purpose. The egg tooth helps the babies to break through the tough, typically leathery eggshell. Most birds, some snakes and all crocodiles have egg teeth as well.
Cuteness overload: Baby anole lizard.
Mother lizards – chameleons, for example – can lay from as few as two to as many as 100 eggs in a clutch, with larger species laying greater quantities. One lizard, the green anole, is nothing if not consistent, laying an egg roughly every 10 days throughout the summer, ending up with a dozen or so eggs. Gestation also varies considerably among lizard species, lasting 50 days in the case of the leopard gecko and as many as 24 months for the rare Parson’s chameleon.
A baby blue-tongued skink found in New South Wales, Australia.
Despite their differences, all lizards are essentially born as miniature, cuter replicas of their parents, ready to start hunting for insects or feeding on vegetation. There is, however, an exception to the rule of reptile babies being left to fend for themselves – the aforementioned Solomon Islands skink. These large skinks live in a group called a circulus, and both the parents and other adults in the group are fierce protectors of the offspring for about a year (and sometimes more) after their birth.
Another baby lizard slinks along someone’s palm.
The Solomon Islands skinks invest a large amount of time and energy into carrying their young during the gestation period, which lasts for six to eight months. The size of each baby at birth makes the skink’s situation equivalent, in the words of Philadelphia Zoo reptile curator Dr. Kevin Wright, to “a human mother giving birth to a six-year-old.” It’s understandable that skinks want to protect their investment, with usually only one baby born at a time – in rare cases, twins.
Overall, however, these fascinating creatures receive no parental care once hatched, meaning their survival comes down to their inherent wits and skills.
A bearded dragon, around 3 week old.
Yet how lizards make their babies in the first place is equally as interesting as how the babies are born and nurtured. When it comes to mating, lizards have a couple of little surprises up their sleeves…
A little lizard for sale in a Moroccan bazaar.
First of all, some female lizards can store sperm inside their bodies for a considerable time after an encounter with a male. Veiled chameleons, for example, hold onto the sperm for months on end, while green anoles can retain some some into the next breeding season. This means that these prudent lizards might appear to reproduce without any apparent male participation – which can likely come as a shock to exotic pet owners who weren’t aware of this when they bought them from a breeder!
A friendly baby lizard found in the garden.
Another strange fact about lizard reproduction is that certain types can have ‘virgin births’. In a phenomenon known as parthenogenesis, some species of whiptail lizards, geckos and komodo dragons are capable of reproducing asexually. In the case of some whiptails and one gecko species, all individuals are female and solely use parthenogenesis – while the komodo dragon, amazingly, can reproduce both sexually and asexually.
A newborn baby anole lizard photographed in Florida.
Male lizards have a couple of interesting tricks to call upon as well. All male lizards have a pair of reproductive organs called hemipenes. Each hemipenis is usually kept inverted inside the body (at the base of the tail) when not in use. Then, when the moment is right, the amorous male will come up to the female from the side, bite his love interest’s neck, and use the hemipenis nearest to her to mate.
To think that these bestial fully-grow males were once as cute – and in some cases as small – as buttons!