Scalloped Hammerhead Shark


Form & Function


        Obviously the adaptation of the hammerhead possessed by the Sphyrna lewini is a very intriguing one.  The outward extensions of their head that make up the “hammer” are known as cephalofoil. By definition, the prefix "cephalo" means "head" (Kaijiura and Holland 2002). Obviously this form has a lot to do with biological adaptation. Despite being around for a long while, the function of the cephalofoil is still highly debated. In reality, it has multiple purposes.

        One of these functions is improved binocular vision. We as humans also use this type of vision. Binocular vision forms two overlapping views, one from each eye, and creates depth perception. The position of the Sphyrna lewini’s eyes on the sides of their hammerheads creates greater binocular vision which obviously helps them when hunting for prey (McComb et al. 2009).

        Another function related directly related to the organism’s cephalofoil is quicker, sharper turning. The properties of the cephalofoil make the shark much more hydrodynamic. This decreases resistance in the water, thus allowing them to make very quick and sharp turns while hunting for prey (Lim et al. 2010).




         It doesn’t seem as though the scalloped hammerhead shark needs another hunting advantage, but it has one in electroreception. Electroreceptors allow the sharks to detect electric fields and thus locate prey in the water. Once again the cephalofoil provide an advantage. They increase electrosensory area for the Sphyrna lewini (Kaijiura and Holland 2002).

         As I have stated previously, this organism’s cephalofoil make them very hydrodynamic. This adaptation also comes into play in the olfactory or smell sense. A narrow groove in the cephalofoil allow a very large volume of water to enter the body. The olfactory organ of this organism just so happens to have an abundance of lamellae which play a role in surface area of the olfactory nerves (Rygg et al. 2013). More specifically, the basic role of lamellae is increasing the amount of oxygen in the bloodstream. (Rygg et al. 2013).This means that the hammerhead shark can take in a lot of water for its above average sense of smell.

        Sphyrna lewini have clearly come a long way in adapting to their aquatic environment. The “hammer” formation has multiple purposes which ultimately give the organism several advantages in catching prey. These adaptations help to mask the species’ lack of size when compared to other types of sharks.

                        Photo credit: Frederic Buyle

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