Hammerhead Shark Identification Guide
How to recognize a hammerhead and tell the common species apart by head shape.
Read the full Hammerhead Shark encyclopedia entry →
Hammerhead Sharks (family Sphyrnidae) are unmistakable thanks to their flattened, laterally extended heads, called cephalofoils. Species are separated mainly by head shape.
Key identification features
- A wide, flattened, T-shaped head with the eyes and nostrils spread to the ends.
- A tall, curved first dorsal fin.
- A slender, grey-brown shark body with a white underside.
Telling species apart by the head
- Great Hammerhead: nearly straight front edge to the head with a central notch; very tall, sickle-shaped dorsal fin — the largest species.
- Scalloped Hammerhead: front edge of the head is scalloped with several indentations.
- Smooth Hammerhead: broad head with a smoothly curved front edge and no central notch.
- Bonnethead: small, with a rounded, shovel-shaped head.
Where you'll see one
Hammerheads occur in warm coastal and open waters worldwide, sometimes in large schools. The mallet-shaped head identifies the group instantly; the shape of its front edge names the species.
Frequently asked questions
Why do hammerheads have that head shape?
The wide 'cephalofoil' spreads their eyes and sensory organs apart, improving vision and prey detection — and it is the key identification feature.
How do I tell a Great from a Scalloped Hammerhead?
The Great Hammerhead has a nearly straight head edge with a central notch, while the Scalloped Hammerhead's head edge has several scalloped indentations.