Life Cycle
of a Frog
1. Eggs
This is an
egg mass laid by a frog. Each of those black dots is made up of a bunch of
cells that will eventually grow into a tadpole.
2. Tadpole
Within a few days, the eggs develop into tadpoles.
Tadpoles live completely underwater. After a few weeks, a hormone in the
tadpole’s thyroid gland initiates metamorphosis.
3. Tadpole with
hind legs
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.
4. Tadpole with
front and hind legs
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’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.
5. Froglet (or
young frog)
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.
6. Adult
This is a
fully grown frog. frogs go through a lot to get to this phase. They even go
through changes that aren’t visible in these pictures. The tadpole’s horny
teeth, once used to tear up plants, disappear and tongue muscles develop to
catch insects. The tadpole’s large intestine, important for digesting algae and
plants, shrinks to suit the frog’s meat-eating
diet.
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