Get That Chickadee Feeling

Home

Free Teacher's Guide
BOOMer Rules
2007

Life Cycle of a Frog

Spawn (egg-mass)

The male frog fertilizes the eggs as they get are laid. Frogs tend to lay eggs in masses, whereas toads usually lay eggs in long chains. Bullfrogs lay eggs in a giant floating raft. The eggs taste terrible so other animals will not eat them. Some of the adult frogs leave after this point, but others stick around to watch over the little ones. Some have very unusual ways of caring for their young such as caring for them while in their mouth.

Egg

Frogs and Toads tend to lay many eggs because there are numerous hazards between fertilization and full grown frogs! Those eggs that die tend to turn white or opaque. The lucky ones that actually manage to hatch still start out on a journey of many perils.
Life starts when the central yolk splits in two. It then divides into four, then eight, etc.- until it looks a bit like a raspberry inside a jello cup. Soon, the embryo starts to look more and more like a tadpole, getting longer and moving about in its egg.
Usually, about 6-21 days (average!) after being fertilized, the egg will hatch. Most eggs are found in calm or static waters, to prevent getting too banged around in a current of water.
Some frogs, like the Coast foam-nest tree frog, actually mate in tree branches overlooking streams. Their egg masses form large cocoon-like foamy masses. The foam sometimes cakes and dries in the sun, protecting the inside moisture. After development of 7 to 9 days and the rain comes, the foam drips down dropping tiny tadpoles into the river or pond below.

Shortly after hatching, the tadpole still feeds on the remaining yolk, which is actually in its gut! The tadpole at this point consists of poorly developed gills, a mouth, and a tail. It is very fragile at this point. They usually will stick themselves to floating weeds or grasses in the water using little sticky organs between it’s' mouth and belly area. In 7 to 10 days, it will begin to swim around and feed on algae.
After about 4 weeks, the gills are grown over by skin, until they eventually disappear. The tadpoles get tiny teeth which help them grind food turning it into soupy oxygenated particles. They have long coiled guts that help them digest as much nutrients from their meager diets as possible.
By the fourth week, tadpoles can actually be fairly social creatures. Some interact and school like fish!
 

Tadpole with legs

After about 6 to 9 weeks, tiny legs start to sprout. The head becomes more distinct and the body elongates. By now the diet may include larger items like dead insects and even plants.
The arms will begin to bulge where they will eventually pop out, elbow first. After about 9 weeks, the tadpole looks more like a frog with a long tail. It is now well on it's way to being full-grown!

Young Frog or Froglet

By 12 weeks, the tadpole has only a small tail stub and looks like a miniature version of the adult frog. Soon, it will leave the water.

By between 12 to 16 weeks, depending on water and food supply, the frogs complete their full growth cycle. Some frogs that live in higher altitudes or in colder places might take a whole winter to go through the tadpole stage. These frogs will start the whole process again, finding mates and creating new frogs.

Home