Mammals have nervous, digestive, circulatory, skeletal, immune, muscular, integumentary, and excretory systems.
Birds and mammals both have internal skeletons, closed circulatory systems, similar digestive systems, and are warm blooded.
The internal anatomy of fetal pigs is not very different from humans. It is slightly underdeveloped but the internal systems are conserved across all mammals.
All mammals have an internal skeleton
polar bears are internal because they are mammals and all mammals are internal.
Mammals have internal gestation with viviparous birth.
All mammals use internal fertilization.
Opossums are marsupial mammals - they have internal fertilization as all mammals do.
Orangutans are mammals who have internal skeletons.
Internal - they're mammals.
yes
mammals
internal. They develop inside the womb