Skink: Eggs, Babies or Both?

Jul 4, 2011 By Arati Rao

A yellow-bellied three-toed skink (a type of lizard with very short legs that moves like a snake) has become the center of attraction for scientists lately. Here’s why: the skinks living in the warm coastal lowlands of Australia are oviparous (they lay eggs). But members of the same species have begun opting for live births (no eggs, directly giving birth to babies) further up in the cooler climates of the mountains. So does the yellow-bellied three-toed skink lay eggs or give birth to live babies? Both … for now!

And THAT is what is exciting. 

The yellow bands you see are embryos the skink is carrying

What's special about this?

Over time, several species of reptiles have made the transition from egg-laying to live births. But looking at a reptile giving birth to babies does not give an insight in to how they made that transition. This skink species is like a developing story! If you were a herpetologist (someone who studies reptiles), this would be a chance of a lifetime.

How does the skink do that?

Scientists know that the process of giving birth in mammals is highly advanced. Food and oxygen for the developing baby comes through a sac called the placenta. Correspondingly, when a reptile lays eggs on the ground, the nourishment for the unborn baby comes from the yolk and much needed calcium comes from the porous eggshell.

If a reptile is moving from laying eggs to live births, what might be happening to make sure that the baby gets its nourishment? The scientists decided to check what was happening in the yellow-bellied three-toed skink that lived in the cool mountains.

Well, it turned out to be a rather smooth transition! The mother’s womb seemed to secrete calcium that got absorbed into the embryo. Scientists believe that this is the beginning of placenta-formation in reptiles. The ease of the switch is likely why there have been so many instances in history of species making the change from egg-laying to live births. 

This research was published in the Journal of Morphology in August 2010 by James Stewart from East Tennessee State University and co-authors.

Which reptile fascinates you the most and why?

kristineg (not verified)   3 years ago

i like it because i am a tomboy and gross things r cool

JENNAH H_C   4 years ago


dolphingirl   4 years ago

I think the Basilisk is the coolest.It can walk on water!

owenh   4 years ago

That is so cool. Why do they even need them?

garatig   4 years ago

WOW what a strange animal and what strange things it does!

laraluna15 (not verified)   5 years ago

Those Skinks are really cool. Wouldn't it be weird if human-beings did the same thing!!!!!!

laraluna15 (not verified)   5 years ago

Those things are really cool, and they are soooo cute!!!

laraluna15 (not verified)   5 years ago

Those things are really cool!!!!!

T-bone   5 years ago

that lizard is really cute

Liliana   5 years ago

i think i've seen one of those before. It was cute!

aj (not verified)   5 years ago

they look like they have arms

Ami   5 years ago

Skinks are so cute! I prefer snakes though, even though they seem very similar.

Liliana   5 years ago

yeah, i prefer snakes too, but those are still pretty cute!

arotella   5 years ago

i love to see those iguanas swim

bearse2   5 years ago


Alexandra   5 years ago

ewwwwwww!!! I am glad that i have never seen one of those

Dryden   5 years ago

I like his little arms. It's really shinny, but slimy looking. It's kind of disgusting.

Paayal12   5 years ago

The skink looks really cool--like slimy, but kinda cute with its little arms and everything. I have never heard of it, but it's really cool. All reptiles fascinate me...when I went to this one outdoor camp with my school two years ago, I got to hold a couple of snakes. It was awesome!

Emma   5 years ago

I think this skink and other animals that have made the transitions from egg-laying to live births fascinates me because it's just amazing how these animals can adapt to their environment in such a way!

Vikshar   5 years ago

The bearded dragon fascinates me the most because ot it's spiky " mane", and the fact that it can go through a drought for a vast period of time. The reptile mentioned above would be third on my list.

Xenia   5 years ago

The Marine iguana in the Galapagos fascinates me the most because it is the only iguana able to swim. After reading this article, the yellow-bellied three-toed skink has become the second most fascinating.

Aash J   5 years ago

I have been to the Galapagos and those iguanas are awesome...I saw one swimming it was cool.

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Did you know: Skinks are the most diverse group of lizards in the group Scincidae, which has 1200 species?

(Source: Wikipedia)