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A Production of

Sphyrna tudes, Golden Hammerhead
Dr. Kyle Mara - Temple University
Dr. Phillip Motta, University of South Florida
Sphyrna tudes
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Image processing: Dr. Jessie Maisano
Publication Date: 22 Apr 2013


Hammerhead sharks (Elasmobranchii, Carcharhiniformes, Sphyrnidae) are a unique group of cartilaginous fishes that possess a dorso-ventrally compressed and laterally expanded region of the head known as the cephalofoil, formed by lateral expansion and modification of the rostral, olfactory, and optic regions of the chondrocranium (Compagno, 1984, 1988; Haenni, 2001). The degree of lateral expansion is variable generally ranging from 18% of shark total length (TL) in the bonnethead shark, Sphyrna tiburo, to 50% of TL in the winghead shark, Eusphyra blochii. The phylogenetic relationship of hammerhead sharks indicates that the species with the most extreme lateral expansion of the cephalofoil (Eusphyra blochii) is the most basal while the least laterally expanded species (Sphyrna tiburo) is the most derived (Martin, 1993; Lim et al., 2010).

A number of hypotheses have been put forth to explain the evolution of the cephalofoil. The hydrodynamic lift hypothesis states that the cephalofoil provides hydrodynamic lift at the anterior end of the animal, thereby increasing maneuverability (Nakaya, 1995; Driver, 1997). The cephalofoil may also function in prey manipulation (Strong et al., 1990; Chapman and Gruber, 2002). The greater olfactory gradient resolution hypothesis is based on the greater separation distance of the nares in sphyrnid sharks providing enhanced ability to spatially resolve odors on different sides of the head, increased olfactory acuity, and increased sampling area (Johnsen and Teeter, 1985; Kajiura et al., 2005; Gardiner and Atema, 2010). Furthermore, the cephalofoil provides for a greater sampling area than carcharhinid species (Kajiura et al., 2005). A second hypothesis based on sensory biology is the enhanced binocular vision hypothesis (Tester, 1963). This hypothesis states that the placement of the eyes on the laterally expanded cephalofoil enhances binocular vision anteriorly and increases the visual field of sphyrnids (Tester, 1963; Compagno, 1984, 1988). Recent work has shown support for enhanced binocular overlap and a decreased blind area in the most laterally expanded species E. blochii and S. lewini (McComb et al., 2009). The hypothesis that is most commonly proposed concerning the evolution of the sphyrnid cephalofoil is the enhanced electrosensory hypothesis (Compagno, 1984; Kajiura, 2001). The basis for this hypothesis is the idea that the larger the surface area of the cephalofoil is, the greater the surface area that is devoted to electroreception, providing the shark with increased ability to detect and spatially resolve the bioelectric fields of prey (Compagno, 1984, 1988; Kajiura, 2001; Brown, 2002; Kajiura and Holland, 2002). The laterally expanded head also enables sphyrnid sharks to possess ampullary tubules that are longer than those found in carcharhinid sharks (Chu and Wen, 1979) which may confer greater sensitivity to uniform electric fields than their sister taxa (Murray, 1974; Bennett and Clusin, 1978).

Sphyrna tudes (Valenciennes, 1822), the golden hammerhead, is a viviparous inshore species found in water usually shallower than 12 m. It is found in the western Atlantic from Venezuela to Uruguay. Sphyrna tudes is characterized by a cephalofoil that is 28 to 32% of its TL in width, with most being above 28%. The diet of S. tudes consists of small bony fishes, neonate elasmobranchs, swimming crabs, squid, and shrimp. Its anterior teeth are moderately long and weakly serrated and its posterior teeth are mostly cuspidate (Compagno, 1984). Size at birth for S. tudes is ~30 cm TL. Males mature at 110 to 134 cm and females from 120 to 148 cm. Sphyrna tudes reaches a maximum size of 150 cm (Compagno, 1984).

About the Species

This specimen is uncatalogued. It was made available for scanning by Dr. Kyle Mara of Temple University and Dr. Phillip Motta of the University of South Florida. Funding for scanning was provided by an NSF grant (IOS-0640133) to Dr. Motta and support from the Porter Family Foundation. Funding for image processing was provided by the High-Resolution X-ray CT Facility.

About this Specimen

This specimen was scanned at the University Diagnostic Institute, Tampa, Florida for a total of 337 slices. Each 512 x 512 pixel slice is 0.5 mm thick, with an interslice spacing of 0.5 mm and an interpixel spacing of 0.588 mm. Click here to download the original CT data (95 Mb).

About the


Sphyrna tudes page on Wikipedia


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Brown BR. 2002. Modeling an electrosensory landscape: behavioral and morphological optimization in elasmobranch prey capture. Journal of Experimental Biology 205:999-1007.

Bush A, Holland K. 2002. Food limitation in a nursery area: estimates of daily ration in juvenile scalloped hammerheads, Sphyrna lewini (Griffith and Smith, 1834) in Kane'ohe Bay, O'ahu, Hawai'i. Journal of Experimental Marine Biology and Ecology 278:157-178.

Chapman DD, Gruber SH. 2002. A further observation of the prey-handling behavior of the great hammerhead shark, Sphyrna mokarran: predation upon the spotted eagle ray, Aetobatus narinari. Bulletin of Marine Science 70:947-952.

Chu YT, Wen MC. 1979. Monograph of fishes of China (No. 2): a study of the lateral-line canal system and that of Lorenzini ampulla and tubules of elasmobranchiate fishes of China. Shanghai: Science and Technology Press.

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Driver KH. 1997. Hydrodynamic properties and ecomorphology of the hammerhead shark (Family Sphyrnidae) cephalofoil. Dissertation, University of California Davis. 159 pp.

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Haenni EG. 2001. On the growth, functional morphology, and embryological development of the cephalofoil in the bonnethead shark, Sphyrna tiburo. Dissertation, Clemson University. 253 pp.

Hazin F, Fischer A, Broadhurst M. 2001. Aspects of reproductive biology of the scalloped hammerhead shark, Sphyrna lewini, off northeastern Brazil. Environmental Biology of Fishes 61:151-159.

Johnsen PB, Teeter JH. 1985. Behavioral responses of bonnethead sharks (Sphyrna tiburo) to controlled olfactory stimulation. Marine Behaviour and Physiology 11:283-291.

Kajiura SM. 2001. Head morphology and electrosensory pore distribution of carcharhinid and sphyrnid sharks. Environmental Biology of Fishes 61:125-133.

Kajiura SM. 2003. Electroreception in neonatal bonnethead sharks, Sphyrna tiburo. Marine Biology 143:603-611.

Kajiura SM, Forni JB, Summers AP. 2005. Olfactory morphology of carcharhinid and sphyrnid sharks: does the cephalofoil confer a sensory advantage? Journal of Morphology 264:253-263.

Kajiura SM, Holland KN. 2002. Electroreception in juvenile scalloped hammerhead and sandbar sharks. Journal of Experimental Biology 205:2609-2621.

Klimley AP. 1985. Schooling in Sphyrna lewini, a species with low risk of predation: a non-egalitarian state. Zeitschrift für Tierpsychologie 70:297-319.

Klimley AP. 1987. The determinants of sexual segregation in the scalloped hammerhead shark, Sphyrna lewini. Environmental Biology of Fishes 18:27-40.

Klimley AP. 1993. Highly directional swimming by scalloped hammerhead sharks, Sphyrna lewini, and subsurface irradiance, temperature, bathymetry, and geomagnetic field. Marine Biology 117:1-22.

Lessa RP, Almeida Z. 1998. Feeding habits of the bonnethead shark, Sphyrna tiburo, from Northern Brazil. Cybium 22:383-394.

Lim DD, Motta P, Mara K, Martin AP. 2010. Phylogeny of hammerhead sharks (Family Sphyrnidae) inferred from mitochondrial and nuclear genes. Molecular Phylogenetics and Evolution 55:572-579.

Lombardi-Carlson LA, Cortés E, Parsons GR, Manire CA. 2003. Latitudinal variation in life-history traits of bonnethead sharks, Sphyrna tiburo, (Carcharhiniformes: Sphyrnidae) from the eastern Gulf of Mexico. Marine and Freshwater Research 54:875-883.

Lowe CG. 1996. Kinematics and critical swimming speed of juvenile scalloped hammerhead sharks. Journal of Experimental Biology 199:2605-2610.

Lowe CG. 2001. Metabolic rates of juvenile scalloped hammerhead sharks (Sphyrna lewini). Marine Biology 139:447-453.

Lowe CG. 2002. Bioenergetics of free-ranging juvenile scalloped hammerhead sharks (Sphyrna lewini) in Kane'ohe Bay, O'ahu, HI. Journal of Experimental Marine Biology and Ecology 278:141-156.

Mara KR, Motta PJ, Huber DR. 2010. Bite force and performance in the durophagous bonnethead shark, Sphyrna tiburo. Journal of Experimental Zoology Part A Ecological Genetics and Physiology 313:95-105.

Martin A. 1993. Hammerhead shark origins. Nature 364:494.

McComb DM, Tricas TC, Kajiura SM. 2009. Enhanced visual fields in hammerhead sharks. Journal of Experimental Biology 212:4010-4018.

Murray RW. 1974. The ampulae of Lorenzini. In: Fessard A, editor. Handbook of sensory physiology. New York: Springer-Verlag.

Nakaya K. 1995. Hydrodynamic function of the head in the hammerhead sharks (Elasmobranchii: Sphyrnidae). Copeia 1995:330-336.

Stevens JD, Lyle JM. 1989. Biology of three hammerhead sharks (Eusphyra blochii, Sphyrna mokarran, and S. lewini) from northern Australia. Australian Journal of Marine and Freshwater Research 40:129-146.

Strong Jr. WR, Snelson FF, Gruber SH. 1990. Hammerhead shark predation on stingrays: an observation of prey handling by Sphyrna mokarran. Copeia 1990:836-840.

Tester AL. 1963. Olfaction, gestation and the common chemical sense in sharks. In: Gilbert PW, editor. Sharks and Survival. Boston: C.C. Heath and Company. p. 255-285.

Wilga CD, Motta PJ. 2000. Durophagy in sharks: feeding mechanics of the hammerhead Sphyrna tiburo. Journal of Experimental Biology 203:2781-2796.

& Links

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To cite this page: Dr. Kyle Mara, Dr. Phillip Motta, University of South Florida, 2013, "Sphyrna tudes" (On-line), Digital Morphology. Accessed October 21, 2014 at http://digimorph.org/specimens/Sphyrna_tudes/.

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