Classification

Birds and reptiles are both vertebrates descended from a common ancestor. Reptiles are scaly and cold-blooded; birds have feathers, are warm-blooded, and evolved from theropod dinosaurs.

Fish are aquatic vertebrates that breathe through gills, while amphibians live both in water and on land, breathing through lungs and moist skin. Together they form two of the five main vertebrate groups.

Invertebrates are animals without a backbone. They make up over 95% of all animal species and include insects, spiders, worms, and molluscs.

Mammals are warm-blooded vertebrates that breathe air, have hair or fur, and feed their young on milk produced by the mother.

Vertebrates are animals with a backbone (vertebral column) that protects the spinal cord. They include fish, amphibians, reptiles, birds, and mammals.