How do reptiles have babies?

One of the most common questions we get is how reptiles, like snakes and turtles, have babies. Do they lay eggs? Do they give birth to live young? Or is it somewhere in between? As it turns out, it depends on the reptile! Let’s take a closer look at the two categories that Chicago-area reptiles fall into.

Oviparous

Oviparous is the word we use to describe egg-laying reptiles, and the Chicago region is home to two oviparous lizard species and several oviparous snake species. The six-lined racerunner and the slender glass lizard (a type of legless lizard) are both found west and south of the city in sand prairies.

The fox snake, gray ratsnake, smooth greensnake, and hognose snake are also oviparous. Dr. Allison studies smooth greensnakes and has observed that the hatching time of the eggs can sometimes change. Some smooth greensnake mothers retain their eggs for a longer amount of time than others. This behavior could allow the mothers to incubate their eggs internally for a longer period of time before laying their eggs.

Ovoviviparous

Ovoviviparous is a word that means the mother carries and hatches the eggs in her body. There are several ovoviviparous snake species in the Chicago region, including the gartersnake, northern water snake, and massasauga. This can look like the snakes are giving birth to live young, but the babies are actually hatching from eggs carried inside the mother’s body. In the colder climates, like the Chicago region, a snake that keeps her eggs inside can better control the incubation temperature as opposed to a snake that lays her eggs.