a.
The Egg
Frogs lay their eggs in
water or wet places. A floating clump of eggs is called frog
spawn.
The large and slippery
mass of eggs are too big to be eaten. This is nature's way of protecting
them. But, the smaller clumps of eggs will be eaten by the creatures
living near or in the pond.
The egg begins as a
single cell. Several thousand are sometimes laid at once. It becomes
surrounded by a jellylike covering, which protects the egg. The female may or
may not stay with the eggs to take care of the young after she has laid them.
The egg slowly develops. But, only a few develop into adults. Ducks,
fish, insects, and other water creatures eat the eggs.
The
single cell in the egg eventually splits into two. These two split making four
cells, and so on. Eventually, there are many cells in the egg.
c.
The Embryo
The mass of cells in
the egg come to form an embryo. Organs and gills begin to form, and in the
meantime, the embryo lives off of its internal yolk. This supplies it with
nutrients for 21 days. Then . . .
d.
The Tadpole
After its 21 day
development period, the embryo leaves its jelly shell, and attaches itself to a
weed in the water. This quickly becomes a tadpole, a baby frog. The
tadpoles grow until they are big enough to break free into the water. This
can take from 3 days to 3 weeks, depending on what kind of frog they will
become. They eat very small plants that stick to larger plants in the
water. These tiny plants are called algae. The tadpole has a
long tail, and lives in the water. It is extremely vulnerable, and must rely on
its camouflage to protect it.
The tadpole has a long
tail, and lives in the water. It is extremely vulnerable, and must rely on its
camouflage to protect it. The tadpoles also face danger by being eaten by
other water animals. Sometimes the pond dries up. As a result the
tadpoles die.
e.
The Tadpole Begins To
Change
After about five weeks, the tadpole
begins to change. It starts to grow hind legs, which are soon followed with
forelegs. Behind their heads bulges appear where their front legs
are growing. Their tails become smaller. Lungs begin to develop,
preparing the frog for its life on land. Now and then, they wiggle
to the surface to breathe in air. The tail becomes larger and makes it
now possible for the tadpole to swim around and catch food. They eat
plants and decaying animal matter. Some tadpoles eat frogs eggs and other
tadpoles.
Over time, the tadpole
becomes even more froglike. They have shed their skin and lips. Its mouth
widens, and it loses its horny jaws. The tail becomes much smaller, and the
legs grow. The lungs are almost functioning at this point.
Eleven weeks after the egg was
laid, a fully developed frog with lungs, legs, and no tail emerges from the
water. This frog will live mostly on land, with occasional swims. The tiny
frogs begin to eat insects and worms. Eventually, it will find a mate.
The way this is done varies depending on the species. The female lays the eggs,
the male fertilizes them, and the whole process begins again.
