Frog: Phd in Metamorphosis

Frogs are amphibians known for their dramatic metamorphosis from tadpoles to adults. With their versatile physiology, they thrive in many environments, from wetlands to forests.

Anatomy:

Frogs are moderately complex. They have a short, broad body, with long hind legs used for jumping and swimming. Many species absorb oxygen and expel carbon dioxide through their smooth skin in addition to their lungs. Frogs have large, bulging eyes with a wide field of vision. The mouth is wide with a sticky tongue used to capture prey, which typically consists of insects. Their digestive system includes a cloaca for excretion. Frogs have a unique three-chambered heart. During their larval stage, frogs have gills for underwater respiration, which are replaced by lungs during metamorphosis.

Evolution:

Frogs are part of the order Anura. Early triassic ancestors of modern frogs were among the first vertebrates to make the transition from water to land. Fossils show that over time, frogs adapted to a more terrestrial lifestyle while retaining an aquatic larval stage, due to DNA mutations which enabled a more robust limb and bone structure, while maintaining overall buoyancy.

Interesting Facts

1. Frogs are powerful jumpers, able to leap up to 20 times their body length.
2. Male frogs often produce croaking calls to attract mates, with each species having its own distinct call.
3. Many species are sensitive to environmental changes like pollution, making them indicators of ecosystem health.