Monday, July 30, 2007

Hammerhead shark fact sheet

Sphyrna zygaena | Smooth hammerhead shark

The smooth hammerhead is the second largest of the hammerhead sharks (the largest is the great hammerhead) and is easily distinguishable by the shape of the head. This species occurs in higher latitudes than any other hammerhead species. They prefer temperate waters and occur worldwide at medium latitudes. In the summer they migrate towards the poles where they can sometimes be seen in large schools (numbering hundreds to thousands). Compared to other hammerheads the smooth hammerhead generally stays closer to the surface, in waters less than 20 m deep. During hot summer days they can be seen swimming, just beneath the surface, with their characteristic dorsal fin exposed. Like all sharks, hammerheads sense electric fields in the water (to detect small muscle contractions of their prey) through sensory pores called ampullae of Lorenzini. Sharks are the most electrically sensitive animals knowns and they may be able to use their ability to detect the magnetic field in the earth.

Length: 
• Adult: 2.5 - 3.6 m
• Pup: 50 - 61 cm 

Weight: 400 kg (maximum)

Depth: Average less than 20 m (maximum 200 m) 


Diet: Crabs, shrimps, lobsters, squid, fish, rays and other sharks


Teeth: 
• Upper jaw: 26 - 32 rows
• Lower jaw: 25 - 30 rows

Longevity: 20 years


Gestation: 10 - 11 months

Status: Vulnerable

In other languages
Portuguese: Tubarão martelo
Spanish: Tiburón martillo
French: Requin-marteau
Italian: Squali martello
German: Hammerhaie
Dutch: Hamerhaai
Swedish: Hammarhaj
Norwegian: Hammarhai
Danish: Hammerhaj
Finnish: Vasarahait
Polish: Głowomłot pospolity 

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