It's the bones.
A shark's "skeleton" is made of cartilage while human skeleton is made of bone.
All mammals have an internal skeleton
Yes!
Yes it is.
Internal Skeleton
internal skeleton
endo-skeleton
any mammal has an internal skeleton but bugs have an exoskeleton
Internal.
A cheetah has an endoskeleton, which is an internal skeleton.
internal
The defining characteristic of a Vertebrate is an internal skeleton. Orangutans have an internal skeleton so they are vertebrates.