No. All penguins are birds, not mammals. The differences between birds and mammals are:
Chinstrap penguins do not breed on the Antarctic continent.
A chinstrap penguin is endothermic, able to maintain its own body temperature. It is a bird, and mammals and birds are endothermic. The term 'endothermic' is the biological term for an animal that is warm-blooded.
in the ground
2
Ringed Penguins, Bearded Penguins, Stone-cracker Penguins
they can hold their breath and use it for something else
i don't know how but there harmful
They use it for warmth.
i dont no
Magellanic and Chinstrap
some kinds of seals
chinstrap, gentoo, and adelie penguins are in the same catagory of penguins i forget what its called