All mammals have an internal skeleton
Yes. Platypuses have a skeleton. They are mammals, and all mammals are vertebrates, meaning they have a backbone and an internal skeleton.
All mammals, birds, reptiles, amphibians, and fish (but not all fish) have internal skeleton.
Yes. All mammals do.
Pigs do not have a soft skeleton. Like other mammals, they have an internal skeleton of calcified bones for support.
Sea otters are mammals and, like all mammals, they are vertebrates because they have a spine and spinal cord, and an internal skeleton. They belong to the Phylum Chordata. Mammals, birds, fish, reptiles and amphibians are all vertebrates.
No. Kiwi are birds, and all birds have an internal skeleton. They are vertebrates, just as mammals are.
Yes. Warthogs are vertebrates. They are mammals, and all mammals are vertebrates because they have a backbone and an internal skeleton.
Everything but bugs
Correct, backbones are missing from arthropods because they are exoskeletal, having a tough outer skeleton rather than an internal skeleton (endoskeleton) like mammals, reptiles, amphibians, and so forth.
No, an exoskeleton is a bugs skeleton or shell, covering the outside of its body. Lions are mammals, therefore, incapable of having or growing an exoskeleton. They have a skeletal system inside their body's, like humans and other mammals.
The bat is a mammal and does not have an exoskeleton. It has an internal skeleton the same as other mammals do. You will find exoskeletons on insects.
No, koalas are mammals, so have an internal skeleton.