Great Hammerheads At Night: Bahamas

Scuba diving in the dark is always an adrenaline rush because you know that there are sharks near you but you can’t see them until they suddenly appear. We love night dives because they add an entirely new dimension to exploring the underwater world. We photographed these great hammerhead sharks around Bimini Island in the Bahamas.

Night1 Great Ham 3

Night1 Great Ham 2Sharks are very comfortable swimming in the water at night. To simplify, their eyes are designed to allow light to pass through the retina twice which enables sharks to see in the dark. It is believed that sharks can see about ten times greater than humans in clear water.Night1 Great Ham 4

They also have a cephalofoil (the hammer) that is full of electrical sensors. These electroreceptors are interconnected jelly-filled pores called ampullae of Lorenzini and aid in hunting as these sensors pick up electrical signals given off by all living creatures including humans. Therefore, a shark at night is very aware of your presence and location in the ocean even though you have no idea where they are.Night1 Great Ham 5

 

Great Hammerheads (#1): Bahamas

Although we love to photograph all sharks, our favorite is the great hammerhead (Sphyrna mokarran). Generally, it is a cautious shark and will keep its distance from scuba divers. There are 9 species of hammerhead sharks worldwide but the great hammerhead is the largest. An average adult reaches lengths of about 3.6 to 4.3 meters (12-14 feet) but can reach 6 meters (20 feet) and exceed 550kg (1,200 pounds).

1 Great Ham 41 Great Ham 5

Great hammerheads are newer sharks on the evolutionary scale and have developed some unusual characteristics. The unique feature of this shark is obviously the head. The “hammer” which is called a cephalofoil is full of electrical sensors. These pores called ampullae of Lorenzini aid in hunting as these sensors pick up electrical signals given off by all living creatures including humans.

1 Great Ham 31 Great Ham 6

As you view these photographs notice how different the shark can look depending on the angle of the photograph. On a larger shark, the cephalofoil is about a meter (3 feet) in length and the eyes are at the ends which gives it a large range of vision.

1 Great Ham 7

The diet of this shark is diverse. They will feed on a variety of fishes including tarpons, porcupine fish and even other sharks. As well, lobster, squid, and octopus form part of their diet.  However, their favorite food is rays. Stingrays bury themselves in the sand and the great hammerhead uses its cephalofoil with its electrical sensors to detect their location.

1 Great Ham 2