Species Facts
Science Name:
|
Sphyrna mokarran
|
World Record:
|
580.59 kg (1280 lb 0 oz)
|
Description
"The streamlined body of the great hammerhead with the expanded cephalofoil is typical of the hammerhead sharks. Adult great hammerheads can be distinguished from the scalloped hammerhead and the smooth hammerhead by the shape of the cephalofoil, which has a nearly straight front margin (as opposed to arched), with prominent medial and lateral indentations. The width of the cephalofoil is 23–27% of the body length. The teeth are triangular and strongly serrated, becoming more oblique towards the corners of the mouth. There are 17 tooth rows on either side of the upper jaw with 2–3 teeth at the symphysis (the midline of the jaw), and 16–17 teeth on either side of the lower jaw and 1–3 at the symphysis.[2]
The first dorsal fin is distinctive, being very tall and strongly falcate (sickle-shaped), and originates over the insertions of the pectoral fins. The second dorsal fin and anal fin are both relatively large, with deep notches in the rear margins. The pelvic fins are falcate with concave rear margins, in contrast to the straight-margined pelvic fins of the scalloped hammerhead. The skin is covered with closely placed dermal denticles. Each denticle is diamond-shaped, with 3–5 horizontal ridges leading to marginal teeth in smaller individuals, and 5–6 in larger ones. The great hammerhead is dark brown to light gray to olive above, fading to white on the underside. The fins are unmarked in adults, while the tip of the second dorsal fin may be dark in juveniles.[2][3]
The average great hammerhead measures up to 3.5 m (11.5 ft) long and weighs over 230 kg (500 lb). A small percentage of the population, mostly or all females, are much larger. The longest great hammerhead on record was 6.1 m (20 ft).[2][3] The heaviest known great hammerhead is a 4.4 m (14.4 ft) long, 580 kg (1,280 lb) female caught off Boca Grande, Florida in 2006. The weight of the female was due to her being pregnant with 55 near-natal pups.[5]"
Sources
"1.^ a b c d e f g h Denham, J., Stevens, J., Simpfendorfer, C.A., Heupel, M.R., Cliff, G., Morgan, A., Graham, R., Ducrocq, M., Dulvy, N.D, Seisay, M., Asber, M., Valenti, S.V., Litvinov, F., Martins, P., Lemine Ould Sidi, M., Tous, P. and Bucal, D. (2007). Sphyrna mokarran. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1. Downloaded on May 20, 2010.
2.^ a b c d e f g h i j k l m Bester, Cathleen. Biological Profiles: Great Hammerhead. Florida Museum of Natural History Ichthyology Department. Retrieved on October 18, 2008.
3.^ a b c d e f Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 548–549. ISBN 9251013845.
4.^ a b Cavalcanti, M.J. (2007). ""A Phylogenetic Supertree of the Hammerhead Sharks (Carcharhiniformes: Sphyrnidae)"". Zoological Studies 46 (1): 6–11.
5.^ a b c ""Record Hammerhead Pregnant With 55 Pups"". Discovery News. Associated Press. July 1, 2006. http://dsc.discovery.com/news/2006/07/24/hammerhead_ani.html?category=earth&guid=20060724100030. Retrieved October 18, 2008.
6.^ Martin, R.A. (Mar. 2007). ""A review of shark agonistic displays: comparison of display features and implications for shark–human interactions"". Marine and Freshwater Behaviour and Physiology 40 (1): 3–34. doi:10.1080/10236240601154872.
7.^ a b Great Hammerhead. Elasmodiver.com. Retrieved on October 18, 2008.
8.^ a b Stafford-Deitsch, J. (1999). Red Sea Sharks. Trident Press Ltd. pp. 92–93. ISBN 1900724286.
9.^ Whitty, J. (2007). The Fragile Edge: Diving and Other Adventures in the South Pacific. Houghton Mifflin Harcourt. pp. 9. ISBN 0618197168.
10.^ a b Hammerschlag, Rick. Sandy Plains: Great Hammerhead Shark. ReefQuest Centre for Shark Research. Retrieved on October 18, 2008.
11.^ Strong, W.R., Snelson, Jr., F.F., and Gruber, S.H. (Sep. 19, 1990). ""Hammerhead Shark Predation on Stingrays: An Observation of Prey Handling by Sphyrna mokarran"". Copeia (American Society of Ichthyologists and Herpetologists) 1990 (3): 836–840. doi:10.2307/1446449. http://jstor.org/stable/1446449.
12.^ Chapman, D.D. and Gruber, S.H. (May 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 (3): 947–952.
13.^ a b Stafford-Deitsch, J. (2000). Sharks of Florida, the Bahamas, the Caribbean and the Gulf of Mexico. Trident Press Ltd. pp. 90–91. ISBN 1900724456.
14.^ Thornley, M., Dante, V., Wilson, P. and Bartholomew, W. (2003). Surfing Australia (second ed.). Tuttle Publishing. pp. 264. ISBN 9625937749.
15.^ ISAF Statistics on Attacking Species of Shark. International Shark Attack File, Florida Museum of Natural History, University of Florida. Retrieved on April 24, 2009."