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Smooth Hammerhead Shark

Sphyrna zygaena

Summary 3

The smooth hammerhead (Sphyrna zygaena) is a species of hammerhead shark, family Sphyrnidae, so named because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape (called the "cephalofoil"), without an indentation in the middle of the front margin (hence "smooth"). Unlike other hammerheads, this species prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes...

Description 4

  Common names: hammerhead (English), shark (English), tiburón (Espanol), cornuda (Espanol)
 
Sphyrna zygaena (Linnaeus, 1758)


Smooth hammerhead,     Smooth hammerhead shark



A large hammerhead shark  with broad, narrow-blade lateral extensions on the head; width of hammer 26-29% of TL;  front margin of head broadly convex, with prominent side indentations, but no central indentation; front teeth blade-like, with 1 point, lower teeth straight, upper teeth oblique, deeply notched on rear side, weakly serrate in adults; rear teeth like front teeth; nostrils short, before eyes on head plane; 5 gill slits, last one over front of pectoral fin; 2 dorsal fins, first moderately large and erect, its rear margin concave; second dorsal and pelvic fins low, rear edge of pelvic ~ straight; anal fin base ~ equal to base of second dorsal fin, its rear margin prominently notched; origin of second dorsal fin slightly behind origin of anal fin; transverse pit above tail base crescent shaped, a pit below tail base; tail fin strongly asymmetrical, notched under tip of top lobe, large lower lobe.

Dark olive to dark grey-brown on back and sides, white below; undersides of pectoral fin tips dusky.

Grows to 500 cm and 400kg; size at birth 50-61cm.



A coastal-pelagic and semi-oceanic hammerhead often sighted near the surface.

Depth: 0-200 m.

Circumglobal in tropical and temperate seas; in the eastern Pacific from California to Chile and the Galapagos and Malpelo. Most common in cooler temperate waters.
   

Distribution 5

Southern New England to northern Argentina, straying north to Massachusetts Bay and Nova Scotia.

Morphology 6

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0

Size 7

Maximum size: 4000 mm TL

Description 8

Coastal-pelagic and semi-oceanic. Often found in shallow water over the continental and insular shelves. Enters tropical waters during the winter (Ref. 9710). Feeds chiefly on fish and crustaceans but stingrays serves as a major diet in the warm waters (Ref. 2858). Juveniles live near the coasts. Fast-moving (Ref. 5213). Reported to cause poisoning (Ref. 4690). Meat utilized fresh, dried salted, and possibly smoked for human consumption, liver oil for vitamins, fins for soup, hide for leather and carcasses for fishmeal.

I dnature guides 9

Identification key for shorefishes of the tropical eastern Pacific

Habitat 10

Habitat Type: Marine

Life cycle 11

Viviparous, placental (Ref. 50449), with 20 to 50 young per litter (Ref. 6871)after a gestation period of 10-11 months (Ref.58048). Size at birth between 50-60 cm TL (Ref. 13562).

Reproduction 12

Become sexually mature when 250 to 300 cm long. The female gives birth to 30 -40 young per litter . Size at birth between 50-60 cm. TL.

Link to Access Genomic Data 13

http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=195335&lvl=0

Sources and Credits

  1. (c) WoRMS for SMEBD, some rights reserved (CC BY-NC-SA), http://images.marinespecies.org/resized/2157_sphyrna-zygaena-linnaeus-1758.jpg
  2. (c) Biodiversity Heritage Library, some rights reserved (CC BY), http://farm8.staticflickr.com/7209/6918381652_d336ba5288_o.jpg
  3. Adapted by matbio from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Sphyrna_zygaena
  4. Adapted by matbio from a work by (c) Shorefishes of the tropical eastern Pacific online information system. www.stri.org/sftep, some rights reserved (CC BY-NC), http://eol.org/data_objects/26219497
  5. Adapted by matbio from a work by (c) WoRMS for SMEBD, some rights reserved (CC BY), http://eol.org/data_objects/28471445
  6. Adapted by matbio from a work by (c) FishBase, some rights reserved (CC BY-NC), http://eol.org/data_objects/20846794
  7. Adapted by matbio from a work by (c) FishWise Professional, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/24203255
  8. Adapted by matbio from a work by (c) WoRMS for SMEBD, some rights reserved (CC BY), http://eol.org/data_objects/28495887
  9. Adapted by matbio from a work by (c) Discover Life and original sources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11586754
  10. Adapted by matbio from a work by (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28868699
  11. Adapted by matbio from a work by (c) FishBase, some rights reserved (CC BY-NC), http://eol.org/data_objects/20846798
  12. Adapted by matbio from a work by (c) Gulf of Maine - CoML, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/8080416
  13. (c) matbio, all rights reserved

More Info

Range Map

(c) Shorefishes of the tropical eastern Pacific online information system. www.stri.org/sftep, some rights reserved (CC-BY-NC)

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