Lifecycle of a frog
The breeding season for frogs usually occurs during the spring in temperate climates and during the rainy season in tropical climates. When male frogs are ready to breed, they often use loud croaking calls to attract partners. Males produce these calls by filling a vocal sac with air and moving the air back and forth to create a chirp-like sound. A frog begins life as a fertilised egg. The life cycle of a frog consists of three stages: egg, larva, and adult. As the frog grows, it moves through these stages in a process known as metamorphosis. Frogs are not the only animals to undergo metamorphosis; most other amphibians also undergo remarkable changes throughout their life cycles, as do many species of invertebrates. During metamorphosis, two hormones, prolactin and thyroxine, control the transformation from egg to larva to adult.