Pictures from Bioinfo Animal
Pictures Archive, and Scuba Diving and Snorkeling World Wide with
Carl Roessler. See bibliography.
Appearance: The hammerheads are the most distinguishable of the sharks with their wide, blunt heads in the shape of a doubleheader hammer. The Scalloped Hammerhead are light gray with white undersides. They typically grow to be 8 to 10 feet in length, and weigh 250 to 350 pounds. Their eyes are located on either side of their elongated heads, giving their brains two completely separate images. In relation to their body size, the Scalloped Hammerhead's mouth and teeth are small. The different species of hammerheads are difficult to tell apart by most people.
Range: The Scalloped Hammerhead is found in all the world's tropical waters, and most warm temperate regions. In late spring to fall they can be sighted in the Gulf of Mexico or off Florida's Atlantic coast. Scalloped Hammerheads have also been seen in the waters of the Mediterranean, Australia, and numerous islands.
Habitat: They prefer to be near shore, sometimes within estuaries or bays. They can also be found wandering offshore, yet this is rare.
Reproduction: Scalloped Hammerheads have live young, as do all the Sphyrnidae. The females come into shallow waters to breed, and the pups are born between October and January. They have litters of between four and 37 pups, which are born about two feet in length. Little else is known of the breeding patterns, as is with most species of sharks.
Most species of hammerheads are solitary, however the Scalloped Hammerhead
is found exclusively in schools. The schools range in numbers, from between
fifty to over 200 individuals. The schooling pattern is believed to be
useful in breeding and hunting. Hundreds of sharks will gather around offshore
islands, lending to stories of their aggressiveness. Within the schools,
they display intricate interactive movements, including a corkscrew rotations.
The Scalloped Hammerhead usually displays non-agressive behavior, yet a
few unofficial attacks have been reported, mostly on spear fishers.
Why the Head?
Of all the sharks, the hammerhead
is probably the most distinct with it's wide, rectangular head. Scientists
have pondered this question, and they have come up with three possible
1. The head may act as a hydrofoil, or wing, allowing the shark better swimming control. It adds
lift to provide them more agility.
2. Water is channeled through grooves on the head, providing enhanced smell.
3. To aid in location of prey, the head is saturated with electromagnetic sensors. This theory is
parallel with the notion that stingrays are a favorite food of the hammerhead, as the sharks then
can detect the stingrays, which hide underneath the sand.
Links to Try:
Scalloped Hammerhead Biology
Beach-Net: The Common Hammerhead Shark
2. Bioinfo Animal Pictures Archive
3. Compton's Encyclopedia Online
4. Encarta Online Concise - Hammerhead Shark
5. From the Shore to the Deep Blue Sea with the San Diego Natural History Museum
6. Hammerhead Sharks
7. PBS: Sea Dwellers
8. Scuba Diving and Snorkeling World Wide with Carl Roessler
9. Shark Attack
10. Shark Species
11. Shark Trust
12. Sportsman's Paradise
13. Why the Hammer Head?