Most frogs spawn in water, where the translucent jelly that protects the eggs absorbs moisture and swells. Some egg clusters form huge masses that spread across the surface of the pond; others become compacted into globular clusters and attach to underwater plants. The fertilized eggs of some frogs are deposited on the ground, in damp leaf litter, muddy nests, or water filled bromeliads. Clutch sizes can vary considerably, to the single egg laid by the Cuban tree toad, to ads many as 35,000 lid by the cane toad.

As the single cell of the fertilized egg undergoes repeated division, the yolk provides nutrition for the developing cells. The rate of development varies, depending on the water temperature, the rate of evaporation, and other factors. By the time the larvae emerges from the egg, it has assumed the familiar tadpole shape: large head, small eyes, and a filmy, elongated tail. As the larvae develops, relying initially on external gills, it scavenges on plants or decaying matter using rows of tiny tooth like denticles inside its horny beak.

The tadpoles will sometimes form large aggregations, which may help to stir up food, increase the tadpoles temperature by mass absorption of sunlight, and even provide some protection from predators by both enhancing the statistical chance that any individual tadpole can be eaten, and in the same way as schools of fish, by having more eyes on the lookout and group movements that may make it harder for predators to aim at a particular target.

As tadpole’s metamorphoses into air breathers, the digestive tract shortens for a carnivorous life, the gills are replaced by lungs, the tail is absorbed, the legs develop, the head and body change to adult form, and true teeth appear. This may take as little as nine days or as long as several years.

Although most tadpoles are vegetarians, some are carnivorous, for instance the Spineheaded tree frog swallows the eggs of other frogs whole. In fact, there are a lot of oddities in the frog world.