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No Records
Occasional
Range

Map base conforms with ICES grid squares.

Smooth Hammerhead Shark, Common Hammerhead Shark, Round 
Headed Hammerhead Shark, Requin-Marteau Commun (Fr), Cornuda 
Cruz (Es).

Sphyrna lewini (Griffith & Smith, 1834), Squalis pictus (Blainville, 
1816), Squalus carolinensis (Blainville, 1816), Sphyrna zigaena 
(Linnaeus, 1758), Spyrna zygaena (Linnaeus, 1758), Squalus malleus 
(Valenciennes, 1822), Squalus zygaena (Linnaeus, 1758), Zygaena 
malleus (Valenciennes, 1822), Zygaena subarcuata (Storer, 1848), 
Zygaena vulgaris (Cloquet, 1830).

COMMON NAMES

• 

Broad, narrow-bladed cephalofoil with no median indention.

• 

Moderately sized first dorsal fin.

• 

Second dorsal fin tiny and set above the anal fin.

• 

Small pelvic fins with almost straight posterior edges.

• 

Large, well developed caudal dorsal lobe with terminal notch.

• 

Dark olive to grey brown dorsally.

• 

White ventrally.

• 

Maximum total length reported to 500cm.

The Smooth Hammerhead Shark is an easily recognised large 
species. In European waters it could be confused with the Scalloped 
Hammerhead Shark, Sphyrna lewini, or the Great Hammerhead Shark, 
Sphyrna mokarran, although both of these species has an indent in 
the very centre of the leading edge of the cephalofoil, a feature the 
Smooth Hammerhead Shark lacks. The first dorsal fin is moderately 
sized with large free rear tips. It originates just behind the pectoral fins 
with the free rear tip ahead of the pelvic fins. The pelvic fins are small 
and square. The second dorsal fin is tiny, comparable in size to the 
anal fin over which it is positioned. The dorsal lobe of the caudal fin is 
large and well developed with a strong terminal notch (Compagno, 
1984).

 Dorsal colouration is from dark olive to dark grey with no 

patterning, although some individuals have dusky or black edged fins. 
It is white ventrally. There are reports of the Smooth Hammerhead 
Shark reaching 500cm in length, although 250-350cm individuals are 
more common (Bester, Unknown). 

The Smooth 
Hammerhead 
Shark has a 
widespread but 
patchy distribution 
in temperate and 
tropical waters 
worldwide. In the 
east Atlantic it is 
known from the 
southern British 
Isles to Senegal and 
the Ivory Coast, 
including the 
Mediterranean Sea. 
It is also known in 
the west Atlantic, 
the Indian Ocean 
and the Pacific 
(Compagno, 1984).

SYNONYMS

DISTRIBUTION

APPEARANCE

SP

Z

Text & Illustrations © Shark Trust 2009

Lateral View (

♀)

Ventral View (

♀)

Smooth Hammerhead Shark

Sphyrna zygaena

N

T

N

AT

M

ED

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SIMILAR SPECIES

Sphyrna lewini, Scalloped Hammerhead Shark
Sphyrna mokarran, Great Hammerhead Shark

 

Smooth Hammerhead Shark

Text & Illustrations © Shark Trust 2009

(Not to scale)

Supported by:

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Smooth Hammerhead Shark 

Sphyrna zygaena

TEETH

The teeth have very broad cusps 
with smooth or weakly serrated 
edges (Compagno, 1984).

HABITAT

The Smooth Hammerhead Shark is found close inshore and over 
the continental shelf to depths of at least 200m, although it prefers 
to stay shallower than 20m. While it is more tolerant of temperate 
waters than any other hammerhead shark, it does make migrations 
towards warmer waters in the winter. This is reversed in the summer 
and it migrates towards the poles into cooler water. During these 
migrations adults may form small groups, and young sharks less 
than 1.5m in length are known to form enormous schools. It is 
usually a solitary animal however. It has been known to enter 
freshwater on occasion (Bester, Unknown).

DIET

A 1999 study showed that cephalopods constitute (68.9%) of 
the diet of the Smooth Hammerhead Shark, followed by teleost 
fish (29.8%) with small amounts of other chondrichthyans and 
benthic invertebrates (mostly crustaceans) (Cortés, 1999). However, 
other studies have shown them to be primarily piscivores with a 
preference for other elasmobranchs, especially in inshore areas 
(Bester, Unknown). Compagno (1984) lists the main prey items as 
herring, menhaden, sea catfishes, sea bass, mackerel, porgies and 
also small sharks, skates, stingrays, shrimp, crabs, barnacles, squid 
and other cephalopods (Compagno, 1984).

Like Carcharinidae and other Sphyrnidae species, the Smooth 
Hammerhead Shark reproduces through placental, or yolk-sac, 
viviparity. For about the first third of the gestation period, the 
embryos are nourished by a yolk supply in a very similar way to the 
60% of elasmobranchs which reproduce through normal viviparity. 
However once this yolk supply is used up the yolk-sac changes, 
becoming more folded and wrinkled. It now interlocks with the 
lining of the mother’s uterus. The blood supply to both the yolk-sac 
and the uterus wall increases allowing nutrients and oxygen to pass 
from the mother to the embryo and vice versa for waste, very much 
like a mammalian placenta (Martin, 1994).

Female Smooth Hammerhead Sharks reach sexual maturity 

at around 270cm in length, males at around 210–250cm. Mating 
and birth both occur during the summer with a gestation period 
of 10–11 months. Litters of 20–40 pups have been reported with 
each pup measuring around 50cm in length at birth. It gives birth 
in inshore nursery areas such as lagoons and estuaries where the 
young form large schools (Bester, Unknown).

REPRODUCTION

Text & Illustrations © Shark Trust 2009

ECOLOGY AND BIOLOGY

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COMMERCIAL IMPORTANCE

A common and fairly abundant species, the Smooth Hammerhead 
Shark is taken with pelagic longlines, handlines and pelagic and 
bottom trawls. Its meat is not considered to be high quality but it 
is used fresh, dried salted and smoked for human consumption. 
Its hide is used for leather, its liver oil for vitamins and its fins are 
highly prized for sharkfin soup. Its carcass can also be processed for 
fishmeal (Compagno, 1984).

IUCN RED LIST ASSESSMENT

Vulnerable (2005).

While the Smooth Hammerhead Shark is an abundant and 
widespread species, population trends are poorly understood 
and fishing mortality is likely to be significant. While there are few 
targeted fisheries, it is taken as bycatch across its range by longline, 
handline and trawl fisheries. Due to the high value of its fins, 
animals taken as bycatch are unlikely to be returned alive (Casper et 
al., 2005).

•  Handle with care.
•  Large, powerful shark.
•  Sharp teeth and abrasive skin.

 

Smooth Hammerhead Shark

Text & Illustrations © Shark Trust 2009

Supported by:

THREATS, CONSERVATION, LEGISLATION

HANDLING AND THORN ARRANGEMENT

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BESTER, C. Unknown. Smooth Hammerhead. Florida Museum of 

Natural History. www.flmnh.ufl.edu/fish/.

COMPAGNO, L. J. V. 1984. Sharks of the World: An Annotated and 

Illustrated Catalogue of Shark Species Known to Date. Volume 
4, Part 1. Hexanchiformes to Lamniformes. FAO. Rome, Italy.

CORTÉS, E. 1999. Standardized Diet Compositions and Trophic 

Levels of Sharks. ICES Journal of Marine Science. 56 (5): 707-717.

FERRETTI, F., MYERS, R. A., SERENA, F., LOTZE, H. K. 2008. Loss 

of Large Predatory Sharks from the Mediterranean Sea. 
Conservation Biology. 22 (4): 952-964.

MARTIN, R. A. 1994. From Here to Maternity. Diver Magazine, April 

1994.

CASPER, B. M., DOMINGO, A., GAIBOR, N., HEUPEL, M. R., KOTAS, E., 

LAMÓNACA, A. F., PÉREZ-JIMENEZ, J. C., SIMPFENDORFER, C., 
SMITH, W. D., STEVENS, J. D., SOLDO, A., VOOREN, C. M. 2005. 
Sphyrna zygaena. In: IUCN 2009. IUCN Red List of Threatened 
Species. www.iucnredlist.org.

REFERENCES

Smooth Hammerhead Shark 

Sphyrna zygaena

Text & Illustrations © Shark Trust 2009

Text: Richard Hurst.
Illustrations: Marc Dando.

Citation
Shark Trust; 2010. An Illustrated Compendium of Sharks, Skates, Rays 
and Chimaera. Chapter 1: The British Isles and Northeast Atlantic. Part 
2: Sharks.

Any ammendments or corrections, please contact:
The Shark Trust
4 Creykes Court, The Millfields
Plymouth, Devon PL1 3JB

Tel: 01752 672008/672020

Email: enquiries@sharktrust.org

For more ID materials visit www.sharktrust.org/ID.

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