Frog

The life cycle of a frog begins when the female returns to a pond or stream to lay her eggs. The following picture shows the life cycle of a frog which is similar to that of a toad. A frog's eggs are laid as a mass while a toad's eggs are laid in strings.

Phase 1 - Egg A Female frog lays a few hundred eggs each time. Each egg is protected by a jelly-like-substance. The black spt in the centre is the embryo of a frog. The embryo grows by cell division which hatches to become a tadpole.

Phase 2 - Tadpole Each tadpole swims about freely and feeds on microscopic plants and decaying animal matter. A tadpole breathes through external gills that will gradually give way to internal gills like those of a fish.

Phase 3 - Mature Tadpole A mature tadpole with a pair of hind legs appears at 6-8 weeks.

Phase 4 - Young frog with Tail Young frog with tail - At three months the lungs begin to develop and the forelimbs appear. Meanwhile the tail shrinks.

The young frog loses its gills and can now come on land and breathe air with lungs. It still bears a stump of the tail.

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