Page "Amphibian" Paragraph 76

Frog larvae are known as tadpoles and typically have oval bodies and long, vertically flattened tails with fins.

The free living larvae are normally fully aquatic but the tadpoles of some species such as ( Nannophrys ceylonensis ) are semi-terrestrial and live among wet rocks.

Tadpoles have cartilaginous skeletons, gills for respiration ( external gills at first, internal gills later ), lateral line systems and large tails which they use for swimming.

Newly hatched tadpoles soon develop gill pouches which cover the gills and their lungs develop early and are used as accessory breathing organs, the tadpoles rising to the water surface to gulp air.

Some species complete their development inside the egg and hatch directly into small frogs.

These larvae do not have gills but instead have specialised areas of skin through which respiration takes place.

Tadpoles do not have true teeth but, in most species, the jaws have long, parallel rows of small keratinized structures called keradonts surrounded by a horny beak.

Front legs are formed under the gill sac and hind legs become visible a few days later.

Tadpoles are typically herbivorous, feeding mostly on algae, including diatoms filtered from the water through the gills.

They are also detritivores, stirring up the sediment at the pond bottom and ingesting edible fragments.

They have a relatively long, spiral-shaped gut to enable them to digest this diet.

Some species are carnivorous at the tadpole stage, eating insects, smaller tadpoles and fish.

Young of the Cuban tree frog ( Osteopilus septentrionalis ) can occasionally be cannibalistic, the younger tadpoles attacking a larger, more developed tadpole when it is undergoing metamorphosis.