Sharks hammerhead

Lyle, J.M. 1984. Mercury concentrations in four carcharhinid and three hammerhead sharks from coastal waters of the Northern Territory. Austral. Jour. Mar. Freshwater Res. 35 441 -451. 

Various specialized structures may aid in sampling air or improving directional smelling. The elephant s tnmk can be seen as an olfactory periscope tube-nosed bats Murina and Harpiocephalus spp., Vespertilionidae) and hammerhead sharks (Sphyrnidae) represent bizarre examples of specialized olfactoiy anatomy. Nostrils of lower vertebrates tend to be farther apart than those of higher vertebrates that have more flexible heads and necks (Stoddart, 1983). 

Many marine species also possess the tyrosinase-mediated pathway to synthesize the UV-absorbing pigment melanin. Melanin occurs in a wide range of taxa including bacteria, fungi, invertebrates, and chordates. While much is known about the role of melanin in the UV protection of mammalian skin, very little research has been conducted to examine the efficiency of melanin as a UV-protective mechanism in aquatic taxa.9 It is known that melanin levels in juvenile hammerhead sharks, Sphyrna lewini, are directly correlated to solar UV exposure in the freshwater crustacean Daphnia pulex, melanin concentrations are genetically determined within populations and are correlated to UV sensitivity.50-51 The few studies that have been undertaken suggest that melanin has an important role in UV protection in aquatic environments. 

Lowe, C. and Goodman-Lowe, G., Suntanning in hammerhead sharks, Nature, 383, 677, 1996. 

Shark cartilage powder, prepared from cartilage from the fins of hammerhead sharks (Sphyma lewini) or spiny dogfish Squabis acanthias), is promoted as a treatment for arthritis and cancer (43), based on antiangiogenic properties, but crude extracts are ineffective (44), presumably because the active constituents, such as sphjmastatins are not absorbed. 

Sphyrna zygaena Smooth hammerhead shark Muscle Off Baja California Sur, Mexico 0.73 Escobar-Sanchez et al. (2010)... 

Storelli MM, Ceci E, StoreUi A, Marcotrigiano GO (2003) Polychlorinated biphenyl, heavy meted, and methylmercury residues in hammerhead sharks contaminant status and assessment. Mar Pollut Bull 46 1035-1048... 

The United States, Japan, and the countries of the European Union are net importers of seafood. Between 1986 and 2009, the world population of hammerhead sharks declined by 89 percent— largely from finning to make soup. 

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