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Frog Development from Tadpole to Froglet to Adult
from Science Prof Online
Page last updated 10/2014
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American Bullfrog Metamorphosis: Tadpole to Frog
This page is devoted to bullfrog tadpole metamorphosis with photos of our bullfrogs at different stages of their development, featuring the three bullfrog tadpoles that we followed through metamorphosis.
The information on this page falls into four categories:
- Bullfrog tadpole before metamorphosis.
It can take up to two years for bullfrog tadpoles to change into frogs, but once front legs appear, change happens very quickly. It takes less than 10 days for a bullfrog tadpole to change into a frog once it sprouts front legs !
BIGGIE TAD's Metamorphosis
Bullfrog Tadpoles Before Metamorphosis
For several months the tadpoles just grew bigger, but not at the same rate, so they ranged in size from very big Tads to teeny Tads. Here are pictures of our tadpoles before they began metamorphosis.
1. The tadpoles were shipped to us in Michigan during winter. They arrived in a large cardboard shipping box with a Styrofoam box inside and a heat pack. 2 & 3. The tadpoles mouths are surrounded by little "whiskers" to help them suck up algae and nibble on plants in the tank.
4. Side view of American bullfrog tadpole. 5 & 6. Although similar in size when shipped to us, the tadpoles grew at different rates.
American Bullfrog Metamorphosis
Since we received the tadpoles in December 2012, five have died. Four died as tadpoles and one jumped out of a small opening in the tank, after changing into a frog (we have since closed that opening). Below are the three tadpoles that we have tracked, or are tracking through metamorphosis: Biggie Tad, Lumpy & Tiny Tad. Biggie is the frog who died after jumping out of the tank.
Rear legs first appeared 5/17/13
Two days later rear legs larger and bend at knee 5/19/13
Rear legs well-developed 6/9/13
Tadpole has front legs and body begins to change shape 6/18/13
Tadpole now looks like a frog with a tail 6/21/13
Tadpole continues to reabsorb tail 6/23/13
Biggie Tad is a frog 6/25/13
Time Table for
BIGGIE TAD's Metamorphosis
- Tadpole ~ 9 months old before began metamorphosis.
- Began metamorphosis 5-17-13: Rear legs appeared.
- 23 days: Rear legs continued to grow.
- 32 days: Front legs appear and head begins to change shape.
- 35 days: Tadpole looks like frog with tail. Begins reabsorbing tail.
- 37 days: Froglet continues reabsorbing tail.
- 39 days: Metamorphosis complete.
Rear legs first appeared 6/22/13
Five days later rear legs much larger and bent at the knee 6/27/13
Rear legs well-developed 7/14/13
Well-developed arms, probably started yesterday. Head starting to change shape 7/16/13
See how shape of head has changed, with eyes raised 7/17/13
Time Table for
- Tadpole ~ 10 months old before began metamorphosis.
- Began metamorphosis 6-22-13: Rear legs appeared.
- 22 days: Rear legs continued to grow.
- 24 days: Front legs appear and head begins to change shape.
- 26 days: Tadpole's head is changing shape, eyes raised, mouth enlarging.
- 29 days: Tail reabsorbing
- 31 days: Metamorphosis complete. Lumpy is a frog with just a tiny stub of tail remaining.
Tiny tad finally sprouted legs 8-9-13, then metamorphosis stalled. This tadpole stayed the same... tadpole body with tiny rear legs...until he mysteriously disappeared in March 2014. Perhaps Lumpy ate him?
See how mouth is widening 7/18/13
Tail nearly gone. Lumpy looks like frog
As a science educator and mom, I always look for ways to make science fun and interesting for my own elementary school-age children. One of the features of the Home School Science area of this website is a detailed look at our adventures with bullfrogs, including how to find and care for bullfrog tadpoles.
Tail gone. Lumpy is a frog! 7/23/13
Young children are natural born scientists, full of curiosity! Join the at-home experiments and explorations of a scientist mom & her kids.
The SPO website is best viewed in Microsoft Explorer, Google Chrome or Apple Safari.
Latest Tadpole News
Although two of our tadpoles fully morphed into frogs, only one survived and thrives, Lumpy! He is now a little bullfrog and loves to eat chopped earthworms!!