Amphibians (tetrapods) are the first four-limbed vertebrates.

Amphibians, birds, reptiles, and mammals are all classified as tetrapods, a class of vertebrates. All vertebrates that live on land and some ancient land vertebrates that lead aquatic lifestyles are classified as tetrapods (such as dolphins, whales, seals, sea turtles, sea lions, and sea snakes). Tetrapods have four limbs; if they don’t, their ancestors did, which is one of their distinctive features.

Because of their ancestry, some tetrapods, including whales and snakes, are nevertheless classified as tetrapods even though they no longer have all four limbs.

Read Also:

• Invertebrates and Vertebrates – Its Differences
• Difference between Tetrapods and Amphibians
• Difference between Reptiles and Amphibians

Learn more about this topic, here at BYJU’S.