How to Identify Great Hammerhead

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

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal surface is dark olive-gray to brownish-gray, fading to white on the ventral side. No distinctive markings.

Scale type

placoid

Mouth position

inferior

Distinctive features

Largest hammerhead species., Cephalofoil (hammer) is very broad and nearly straight along the leading edge, with only a slight indentation in the center., First dorsal fin is very tall and falcate (sickle-shaped), originating over or slightly in front of the pectoral fin axil., Second dorsal fin is relatively tall with a deeply notched posterior margin., Pectoral fins are large and falcate., Pelvic fins are relatively small and not strongly falcate.

Dorsal fin

First dorsal fin is exceptionally tall and strongly falcate, originating over or slightly anterior to the pectoral fin axil. Second dorsal fin is relatively tall with a deeply notched posterior margin.

Tail fin

Upper lobe of caudal fin is long and strongly notched near the tip; lower lobe is well-developed.

Pectoral fin

Large and falcate.

Distinctive fins

The very tall, falcate first dorsal fin and the nearly straight leading edge of the cephalofoil are key identifiers.

Identification Tips

1. 1

   Cephalofoil Shape

   The leading edge of the hammer is nearly straight, with only a very shallow, often imperceptible, median indentation. This distinguishes it from other hammerheads like the Scalloped Hammerhead (Sphyrna lewini) which has a distinct central indentation and lateral grooves, or the Smooth Hammerhead (Sphyrna zygaena) which has a smoothly arched leading edge without an indentation.

2. 2

   First Dorsal Fin

   The first dorsal fin is notably tall and strongly falcate (sickle-shaped), originating over or slightly in front of the pectoral fin axil. This is a key distinguishing feature from other large hammerheads.

3. 3

   Size

   As the largest hammerhead, its immense size (up to 6.1 meters) is often a strong indicator, especially for mature individuals.

4. 4

   Pelvic Fins

   The pelvic fins are relatively small and not strongly falcate, unlike the Scalloped Hammerhead where they are more falcate.

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