In ponds and quiet waters, tadpoles tend to have plump bodies and high fins.
In rivers etc., tadpoles tend to be more streamlined with long tails and low fins (many having sucker mouths for stability whilst feeding).
A tadpole feeds on algae and other vegetation. If you want to keep tadpoles, they
particularly like boiled lettuce. Also, make sure that you have an end of the tank that has land
(especially moist leaf matter) where the tadpoles may go when they become frogs.
A tadpole actually eats its tail! The tail is absorbed as the frog grows. This can take periods
from hours through to days.
There is an intermediate phase on the cusp of a tadpole becoming a frog where the tadpole
may remain in water as a tadpole or be a frog on land.
Tadpoles can live out of water as long as they remain moist. This particularly helps (at least
for a little while) when ponds start to dry up.
Tadpoles develop more quickly in warm water - but don't boil them! - this is why they tend
to congregate at the edge of a pond in the warmer water. Note that water temperatures over
those experienced on hot days may kill frogs.
Tadpoles have a coiled intestine (since it is hard to digest plant matter so that more time is
required) - the intestine straightens out as the tadpole becomes a frog since frogs are
Some tadpoles actually shrink into becoming smaller frogs.
Be careful of having tadpoles with fish - fish often don't mind the occasional tadpole for a
snack. If you want to mix fish with tadpoles (eg. to keep mosquitoes down) you may wish to
use White Cloud or Mountain Minnow (Tanicthys albonubes) which won't tend to decrease
your tadpole population.
When keeping tadpoles or eggs, it is better to use water from where you got the specimen.
Otherwise, you may use tap water which has been allowed to stand for a few days (tap
water has chemicals which may kill tadpoles/eggs). Also, ensure that your tadpoles/eggs
don't cook in direct sunlight.
Some frogs lay eggs which do not develop into tadpoles. The young actually develop in the
egg and emerge as a frog. Surprisingly, they still have a tail! Some of the larger frogs have
quite tough shells, so the young frogs come equipped with a spike on their snout which helps
pierce the egg (much like reptiles). (As a technical aside, some examples are the microhylids
and New Guinea ranids (other than the rana species)).