2. What are the major groups of vertebrates?

The major groups of vertebrates are classified into five primary classes: 1. **Fish**: This group includes jawless fish (like lampreys and hagfish), cartilaginous fish (like sharks and rays), and bony fish (like salmon and goldfish). Fish are primarily aquatic and have gills for breathing underwater. 2. **Amphibians**: This class includes frogs, toads, salamanders, and newts. Amphibians typically have a life cycle that includes both aquatic (larval) and terrestrial (adult) stages. They are characterized by their moist skin and the ability to breathe through their skin as well as their lungs. 3. **Reptiles**: This group includes turtles, snakes, lizards, crocodiles, and birds. Reptiles are primarily terrestrial and are characterized by their scaly skin and the ability to lay eggs on land. Birds are considered a subgroup of reptiles. 4. **Birds**: Birds are warm-blooded vertebrates characterized by feathers, beaks, and the ability to fly (though not all birds can fly). They lay hard-shelled eggs and have a high metabolic rate. 5. **Mammals**: This class includes animals such as humans, dogs, cats, whales, and bats. Mammals are characterized by the presence of mammary glands (which produce milk), hair or fur, and three middle ear bones. They are warm-blooded and typically give live birth (with some exceptions, like monotremes). These groups represent the diversity of vertebrate life on Earth, each adapted to their specific environments and lifestyles.