Tadpole

A tadpole or polliwog is the larval stage in the biological life cycle of an amphibian. Most tadpoles live in water. They have gills and tails to help them swim, like fish. As tadpoles grow, they go through a process called metamorphosis. During metamorphosis, they change into their adult forms. They develop lungs and lose their tails.

Some amphibians, such as certain frogs in the family Brevicipitidae, skip the tadpole stage. They develop directly from eggs into tiny versions of adults, called "froglets." In other species, tadpoles may hatch inside their mother’s body or stay in a special pouch until they transform.

Even though tadpoles have no bones, scientists have found fossils of them from the Middle Jurassic. This shows that tadpoles have existed for millions of years. In some cultures, tadpoles are eaten as food. They also appear in many folk tales around the world.

Etymology

The word "tadpole" comes from old English words. It is made from "tadde," meaning "toad," and "pol," meaning "head." The word "polliwog" also has similar roots, combining "pol," meaning "head," with "wiglen," which means "to wiggle."

General description

All frogs and toads start life as tiny creatures called tadpoles. Tadpoles look a bit like small fish, with tails and gills, and they live in water. Frog tadpoles usually eat plants, while some other tadpoles eat tiny animals.

When tadpoles first hatch, they have gills on the outside of their bodies. As they grow, they develop legs and lungs. They also change what they eat, moving from plants to small animals. Tadpoles can be different sizes and live in many kinds of water places, from quiet ponds to fast-moving streams. Some frogs even carry their tadpoles on their backs until they are ready to live away from their mother.

Fossil record

Fossil tadpoles, about 10 cm long, have been found in very old rock layers from the Upper Miocene. Even though tadpoles are soft and don’t have hard bones, they were preserved by special films made by tiny living things. Some parts like jaws and bones turned into a thin carbon film.

One of the oldest known tadpole fossils comes from the Middle Jurassic period and belongs to a species called Notobatrachus deguistioi. Scientists discovered this fossil in 2024, showing how ancient these creatures are.

Human use

Tadpoles are eaten in some parts of the world. In China, people collect large tadpoles from a special type of frog to eat. In Peru, tadpoles are also gathered to use as food and medicine.

Mythology and history

In the origin myths of the Wa people in China and Myanmar, the first Wa came from two female ancestors named Ya Htawm and Ya Htai. These ancestors started their lives as tadpoles, called "rairoh", in a lake named Nawng Hkaeo in their homeland.

In ancient Egypt, people used a picture of a tadpole as a special symbol in their numbers. This symbol stood for the number 100,000.