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Frog Eggs
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Amphibians require water to lay their eggs. These are generally laid in a jelly-like mass that keeps them together and offers some protection. There are exceptions to this rule. There are a few species of frogs and salamanders that are called direct developers. These amphibians lay their eggs on land, and do not undergo the tadpole stage.
Tadpole Stage
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In one to three weeks, the eggs hatch and tadpoles emerge. When it hatches, a tadpole still carries some yolk from the egg and will feed on that while moving very little. In about a week, the yolk will be absorbed and the tadpole will begin to move around more. During this time, the tadpole will eat algae and other aquatic vegetation.
Further Tadpole Development
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The tadpole has gills when it hatches, and lungs will form over the next four weeks. At this time, the tadpole is swimming freely about the pond and may swim in schools, like fish. Over the next couple of weeks, the head will take on the adult shape, with the eyes growing larger and more pronounced.
Growing Legs
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During the first six to nine weeks, the tadpole will develop legs. The rear legs will develop first, followed by the front legs. The tadpole will change from using its tail for swimming to kicking with its hind legs in true frog style. During this time, the tadpole will have changed from a diet of algae to one of aquatic insects and other animals.
Becoming a Froglet
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About three months after hatching, the tadpole is starting to look like a miniature frog. It will start to lose its tail and take on the remaining characteristics of an adult frog. Development is usually concluded at about 16 weeks, and the tadpole will emerge from the water and start to live its life on land as an adult frog.
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Development of Tadpoles
Amphibians lay their eggs in water and when, they hatch, tadpoles emerge. These look more like fish than their parents, and undergo a series of physical changes early in life. These changes are described using a frog tadpole as an example.