The number of eggs a frog lays depends upon the species; some frogs can lay up to 20,000 eggs at a time. The eggs are usually laid underwater and hatch within a few weeks.
Female frogs lay their unfertilized eggs in a mass underwater. The males fertilize the laid eggs and the females then cover the eggs in a jelly-like substance. Some species of frogs leave the eggs after they are laid, while some stay with the eggs to protect them. Tree frogs do not lay their eggs in water, but they lay them in a tree over water so that the tadpoles can drop into the water after they hatch.