Sharks have gills that whales lack. Gills are respiratory organs that sharks use to extract oxygen from water. This adaptation allows sharks to breathe underwater by extracting dissolved oxygen from the water that passes over their gills.
Whales, on the other hand, are mammals and breathe air through blowholes located on the tops of their heads. They do not have gills like fish, including sharks, as they have evolved to breathe air directly from the atmosphere.
In summary, the key body part that sharks have, but whales lack, are gills.
