The Outdoor Journal by Kyle Carroll

From tadpoles to frogs

My grandkids and I have a tradition at my house of paddling around the edge of our pond in a pirogue. All of them started when they were one year old or so. As they have grown, they have progressed from just sitting between my knees and observing to now trying to catch bugs and frogs with their butterfly nets. Our pond is small and has no fish in it, so there are always lots of frogs, water bugs and pond plants to be seen. Yesterday they were lucky enough to capture a few bullfrog tadpoles.

The tadpoles had all progressed to the point that they had the beginnings of their hind legs. One was a lot further along than the others and could hop like a frog, so they were able to see the transformation process, called “metamorphosis” illustrated in their bucket of captured tadpoles.

Each one of our little swimmers in the bucket had started out as an egg, floating in a mass of what looked like clear jelly with little black dots in it. When the water warmed, the eggs developed into tadpoles that live completely underwater. After a few weeks, a hormone in the tadpole’s thyroid gland initiates metamorphosis.

Over about a 24-hour period, the tadpole develops into a frog. This means almost every organ has to change so the tadpole can go from living underwater to living on land as an adult frog. This is a pretty amazing process, when you think about it.

After the hind legs have started to form, a pair of front legs will begin to develop and the tail will start to disappear. The tadpole at this stage begins to form a frog-like face. The tadpole’s skull is made out of cartilage (the same stuff your nose and ears are made out of) but during metamorphosis, the cartilage is replaced with bone.

When the tadpole reaches the froglet stage, it is almost a full adult. At this point, the tadpole’s gills have disappeared, and its lungs have enlarged. This means it is ready to leave the water and live on land. Once its tail disappears, it will become an adult frog.

It seems to me that grandkids grow and change almost as fast. Almost.

The Caldwell County News

101 South Davis
P.O. Box 218
Hamilton, MO 64644
Phone: 816-583-2116
news@mycaldwellcounty.com

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