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Smooth hammerhead

Smooth hammerhead
Sphyrna zygaena noaa.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Selachimorpha
Order: Carcharhiniformes
Family: Sphyrnidae
Genus: Sphyrna
Species: S. zygaena
Binomial name
Sphyrna zygaena
(Linnaeus, 1758)
Sphyrna zygaena distribution map.svg
Range of the smooth hammerhead
Synonyms
  • Squalis pictus* Blainville, 1816
  • Squalus carolinensis* Blainville, 1816
  • Squalus zygaena Linnaeus, 1758
  • Zygaena malleus Valenciennes, 1822
  • Zygaena subarcuata Storer, 1848
  • Zygaena vulgaris Cloquet, 1830

* ambiguous synonym


* ambiguous synonym

The smooth hammerhead (Sphyrna zygaena) is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" 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 forming schools numbering in the hundreds to thousands.

The second-largest hammerhead shark after the great hammerhead shark, the smooth hammerhead can measure up to 5 m (16 ft) long. It is an active predator that takes a wide variety of bony fishes and invertebrates, with larger individuals also feeding on sharks and rays. As in the rest of its family, this shark is viviparous and gives birth to litters of 20–40 pups. A relatively common shark, it is captured, intentionally or otherwise, by many commercial fisheries throughout its range; its fins are extremely valuable for use in shark fin soup. This shark is potentially dangerous and has likely been responsible for a few attacks on humans, though it is less likely to encounter swimmers than other large hammerhead species due to its temperate habitat.

The Swedish natural historian Carl Linnaeus, known as the "father of taxonomy", originally described the smooth hammerhead as Squalus zygaena in the 1758 tenth edition of Systema Naturae, without designating a type specimen. The name was later changed to Sphyrna zygaena. The specific epithet zygaena originates from the Greek word zygòn, meaning "yoke", referring to the shape of its head. The Greek name zýgaina had already been used for the hammerhead shark by Aristotle in the second book of his History of Animals. Other common names for this species include common hammerhead, common smooth hammerhead, round-headed hammerhead, or simply hammerhead.


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Wikipedia

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