Because they are animals that have hair, bear live young and feed these young with milk from mammary glands.
Pigs belong to the class Mammalia, which is a group of warm-blooded vertebrate animals that have hair or fur, give birth to live young, and nurse their offspring with milk.
Pigs belong to the Class: mammalia
They belong to the class Mammalia ( mammals).
Elephants belong to the class Mammalia.
Kangaroos are mammals, so they are in the class mammalia. They are marsupials, and macropods.
Lions (Panthera leo) are in the class Mammalia (mammals).
A bull belongs to the class Mammalia.
Tigers belong to Class Mammalia.
Opossums belong to the class mammalia.
Class Mammalia.
They're mammals Mammalia.
Orcas are the largest member of the dolphin family, an aquatic member of the class Mammalia.