Why seals and sea lions would not be considered fish?

Seals and sea lions are mammals and not fish. Here are a few key reasons why:

1. Mammary Glands: Seals and sea lions have mammary glands and produce milk to feed their young. This is a defining characteristic of mammals.

2. Hair or Fur: Seals and sea lions have hair or fur, another distinguishing feature of mammals.

3. Internal Fertilization and Live Birth: Seals and sea lions exhibit internal fertilization, and females give birth to live offspring. This is different from fish, which typically lay eggs.

4. Lungs and Breathing: Seals and sea lions are marine mammals that possess lungs and breathe air, surfacing regularly to take breaths. Fish, on the other hand, use gills to extract oxygen from water.

5. Warm-Blooded (Endothermic): Seals and sea lions are warm-blooded, meaning they can maintain a relatively constant internal body temperature. This is in contrast to fish, which are cold-blooded (ectothermic) and rely on external sources to regulate their body temperature.

6. Vertebral Structure: The vertebral structure and bone composition of seals and sea lions differ from that of fish. Mammals typically have a well-developed vertebral column and a skull.

7. Communication and Social Behavior: Seals and sea lions display complex communication systems, including vocalizations and body language. They often form social groups and exhibit sophisticated social behaviors. Such advanced forms of communication are not commonly observed in fish.

8. Flippers and Limbs: Seals and sea lions have specialized flippers for swimming and locomotion, along with limbs adapted for terrestrial movement. Fish, on the other hand, have fins for maneuvering in water.

9. Intelligence and Cognition: Seals and sea lions are highly intelligent animals known for their problem-solving abilities and cognitive capacities. Fish, while having certain levels of cognition, do not possess the same degree of higher-order brain functions as mammals.

10. Taxonomy: Seals and sea lions belong to the mammalian order Carnivora, further classifying them as marine mammals. They are taxonomically distinct from fish species.