1. Warm-Blooded: Whales are warm-blooded, which means they can regulate their body temperature internally and maintain a constant body temperature regardless of their external environment.
2. Milk Production: Female whales produce milk to feed their young. Whales have mammary glands, which are specialized glands that produce milk. The milk produced by whales is rich in nutrients and provides nourishment to their calves.
3. Hair: Although whales do not have fur like other mammals, they have hair follicles present in their skin during their embryonic development. These hair follicles are present in certain areas of the body during fetal stages, but they usually disappear as the whale develops and matures.
4. Breathing: Whales breathe air, just like other mammals. They have lungs and take in oxygen through their blowholes, which are located on top of their heads. Whales surface regularly to breathe and exchange air, demonstrating their dependence on atmospheric oxygen.
5. Reproduction and Care for Offspring: Whales reproduce sexually and give birth to live young. Female whales carry their calves during a gestation period, which varies depending on the species. After birth, the calves are nursed and receive parental care and protection until they are independent.
6. Social Behavior: Whales are known for their social behavior. They live in groups, called pods, which can vary in size depending on the species. Some whale species exhibit complex social structures, communication systems, and cooperative hunting techniques.
7. Intelligence and Complex Brain Structure: Whales have relatively large and complex brains compared to other animals. They demonstrate high levels of intelligence, including problem-solving abilities, social learning, and complex vocal communication.
Based on these characteristics, whales are classified as mammals. They share many of the fundamental traits that define mammals, including warm-bloodedness, milk production, lung breathing, and complex social behaviors.