To allow a shark to glide swiftly and elegantly through the water, several distinct anatomical features have developed over the course of 400 million years of shark evolution. First, there is the shark’s overall body shape, which makes locomotion hydrodynamically efficient. Then, there is the shark’s skin, bearing a multitude of tiny denticles that reduce hydrodynamic drag. This surface structure has inspired a search for biomimetic applications in scientists an engineers. But most essential for locomotion are, of course, the fins. Most sharks have eight fins, of which the pectoral and caudal fins are most important for locomotion. Both play different roles in steady swimming and maneuvering. And sharks begin practicing their movements at a very early age; ultrasounds of captive tawny nurse sharks have shown that even as embryos, sharks start migrating between the left and right uteri.
Sources: Biology of Sharks and their Relatives, eds. Jeffrey C. Carrier, John A. Musick and Michael R. Heithaus, Boca Raton, London, New York, Washington D. C. 2004.
Oeffner, Johannes and George V. Lauder, “The hydrodynamic function of shark skin and two biomimetic applications”, J Exp Biol, vol. 1, (2012).
Thomson, Keith Steward and Dan E. Simanek, “Body Form and Locomotion in Sharks”, American Zoologist, vol. 17, issue. 2, (1977).
Tomita, Taketeru et al., “Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other”, Ethology, vol. 125, (2019): 122– 126.