A Frog's Life: How These Creatures Transform

We all know that frogs and toads start out as tadpoles, but what more do we really know about the way the frogs and toads of Will County begin their lives?

A green frog. (Photo by Chad Merda)

Let's take a deep dive into a shallow pond to discover the ins and outs of frog and toad eggs. 

Shells and yolks

A cluster of frog eggs on moss. (Photo via Shutterstock)

Bird eggs have a hard shell that not only protects the growing life within, but it also locks moisture inside the egg. Frog eggs do not look like the bird eggs we are familiar with. They do not have a hard shell, so they need constant contact with water to stay moist.

Because of this, frog and toad eggs are laid underwater. Their eggs do have a protective coating, though. It is made from a jelly-like substance. This substance keeps the eggs together and provides an extra layer of defense from the elements.  

Chicken eggs, as we know, have a bright yellow yolk. This yolk provides nutrients to the growing chick inside. Having a yolk isn't a trait of only bird eggs. Frog and toad eggs have these yellow yolks too. The yolk takes up about half the space inside the jelly-coated egg. This yolk is a food reserve for the tiny tadpole and helps it grow during its embryonic development stage. 

Growing up 

Tadpoles eating algae in the water. (Photo via Shutterstock)

When a tadpole first hatches from its egg, it is not much more than a tail with gills and a mouth. Inside its tiny tummy is the remainder of the jelly and yolk from their egg, which is enough to keep them alive for the first few days of its life. In about a week, the tadpole is stronger and becomes more active. This wiggling creature swims around searching for its favorite food — algae. 

While they transform from tadpole to froglet, they exchange their underwater breathing gills for teeth! By the time the tadpole has back legs, it becomes a carnivore, eating any animal matter it can fit in its mouth. 

Frogs pictured left to right, top to bottom: American toad, cricket frog, gray tree frog, spring peeper, chorus frog, leopard frog, bullfrog, green frog, wood frog.

Now we know what’s going on inside the egg, but there are still a lot of questions to be answered. Is there a difference between the different species of tadpoles? What about eggs? Do they all look the same? How many eggs are laid at once? How long does it take for a tadpole to turn into its adult form? The answers to these questions do not have a one-size-fits-all answer. 

The chart below details the number of eggs the amphibian lays and describes what the eggs look like. Find out how long it takes each species of tadpole to hatch from its egg and turn into a frog. 

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