How to Identify Hammerhead Shark

To identify Hammerhead Shark (Sphyrna), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Typically greyish-brown to olive-green on the dorsal side, fading to white on the ventral side. Some species may have darker fin tips.

Scale type

placoid

Mouth position

inferior

Distinctive features

Cephalofoil (hammer-shaped head) with eyes and nostrils positioned at the ends of the 'hammer'., Laterally compressed body., Large, sickle-shaped first dorsal fin., Asymmetrical caudal fin with a prominent upper lobe.

Dorsal fin

Two dorsal fins; the first is large, erect, and sickle-shaped, originating over or slightly behind the pectoral fin axil. The second dorsal fin is much smaller.

Tail fin

Asymmetrical caudal fin with a well-developed upper lobe and a smaller lower lobe.

Pectoral fin

Moderately large and falcate (sickle-shaped).

Distinctive fins

Pelvic fins are relatively small. Anal fin is present and small.

Identification Tips

1. 1

   Cephalofoil Shape

   The shape and width of the 'hammer' are key. For example, the Great Hammerhead (Sphyrna mokarran) has a nearly straight anterior margin of the cephalofoil, while the Scalloped Hammerhead (Sphyrna lewini) has a distinct indentation in the middle of its cephalofoil. The Bonnethead (Sphyrna tiburo) has a shovel-shaped head.

2. 2

   First Dorsal Fin

   The size and shape of the first dorsal fin, and its origin relative to the pectoral fins, can help differentiate species. The Great Hammerhead has a very tall, falcate first dorsal fin.

3. 3

   Body Size

   Adult size varies greatly among species. The Great Hammerhead is the largest, reaching over 6 meters, while the Bonnethead is one of the smallest, typically under 1.5 meters.

4. 4

   Tooth Morphology

   While difficult to observe in the wild, tooth shape and arrangement can be a definitive identification feature for experts.

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