Set apart from other shark
species by its bizarre head, the hammerhead shark is one of the most
successful predators in the ocean. Sharks have existed on Earth for
about 450 million years. The hammerhead however is the newest member
of the shark family, having lived for only about 20 million years. Hammerhead
sharks can be found in warm and temperate waters across the world, especially
in costal areas. They prefer deep water, though sometimes they will
come into more shallow areas.
The "hammer head" of the hammerhead shark is known as a cephalofoil.
This may look strange, but it's actually an ingenious evolutionary adaptation
that has a variety of uses. Whereas most sharks have their eyes close
together, hammerheads have their eyes positioned on either end of their
wide cephalofoil. This gives them better depth perception and a wider
view of the ocean as they patrol, allowing them to spot prey more easily.
The cephalofoil also gives the hammerhead a greater sense of electromagnetic
fields than other sharks possess. In addition, the cephalofoil allows
the shark to turn in the water more quickly, grants a greater sense
of smell, and can also be used as a tool to catch prey. The cephalofoil
is essentially a built-in multi-purpose tool!
Depending on whom you ask there are eight-to-ten different species of
hammerhead sharks. The largest is the great hammerhead, which reaches
up to twenty feet long. Most hammerheads are smaller by comparison.
Hammerhead sharks are known to migrate in large numbers to cooler waters
during the summer. They prefer to hunt stingrays, and their cephalofoils
help them to locate these sand-dwelling creatures. They will also eat
crabs, octopi, squid, other fish, and sometimes even other sharks. Hammerhead
sharks are viviparous, meaning the shark pups are born live. A hammerhead
shark can give birth to between twenty and fifty pups at a time! What
is even more amazing is that in some circumstances, female hammerheads
are capable of reproducing asexually, meaning they can produce pups
without a mate! While this can increase hammerhead numbers, it reduces
the genetic diversity and makes them more prone to diseases.
Though most hammerheads are considered non-threatening to humans, there
are some species that are dangerous. It is important to understand that
despite their aggressive tendencies, hammerhead attacks on humans are
very rare. Every year humans kill far more sharks than sharks kill humans.
Sharks, including hammerheads, are not savage man-eaters, they are merely
misunderstood carnivores that are important to the health of the ocean.
Sharks keep fish populations in check, and they keep genetic diversity
strong by preying on weaker fish. Sharks are not menaces to the oceans;
rather they help to regulate them.
Some hammerhead species are rated as Least Concern or are not formally
evaluated. However, several species are vulnerable, or even endangered.
This is largely due to overfishing for their fins. Shark fins are a
delicacy in China, where they are made into shark fin soup. They are
obtained in a process called shark finning, where sharks are captured,
their fins are cut off and the sharks are thrown back into the ocean.
Without their fins the sharks cannot swim and process oxygen, thus they
suffocate. Hammerhead fins are especially prized for shark fin soup.
What's more, hammerhead numbers are also greatly harmed by commercial
bycatch around the world.
Though hammerheads are threatened, there is still hope to preserve them.
Check out these awesome organizations that work to protect all sharks,
Bite-Back - A UK
organization dedicated to protecting sharks and other marine species.
Shark Savers - An
organization founded by passionate scuba divers, dedicated to protecting
sharks and manta rays.
Project AWARE - A
campaign run by PADI (Professional Association of Diving Instructors),
dedicated to protecting sharks and removing ocean debris.
WildAid; Shark Page-An
organization dedicated to ending all illegal wildlife trade, including
the trade of shark fins.