References and Further Information: 1  Morrissey, J.F. and J.L. Sumich. 2012. Introduction to the Biology of Marine Life (10th Edition). 2  University of California Museum of Paleontology. Bilateral (left/right) Symmetry.
A lot of things. For one, Whale sharks are fish and use gills to breathe. Blue whales are mammals. The blue whale is also bigger than the whale shark. The tail structure is also different if you watch the whale shark swim, it uses its tail in a side to side motion while the blue whale uses a up and down movement.
The largest whale shark ever measured was 40 feet (12.2 meters) long; however, the species is thought to grow even bigger. Size relative to a bus: As the largest fish in the sea, reaching lengths of 40 feet (12 meters) or more, whale sharks have an enormous menu from which to choose. Fortunately for most sea-dwellersâand us!âtheir favorite meal is plankton.