they have gills to breathe, a streamline body for cutting through the water Answer 2 Many of them also have a swim bladder which is a bladder filled with a gas, which enables them to neither sink nor...
The platypus has webbed feet with a retracting webbed membrane which can expose the claws, enabling the platypus to effectively dig burrows. Its claws are used for digging burrows into riverbanks for...
1. Blowholes (whale,dolphin) 2. Special nostrils which are able to close (penguin) 3. Certain kind of skin(I forgot what) for seals,walruses,dugong,etc. I'm 12 and answering this(; haha