OLogy Cards > hammerhead sharks

hammerhead sharks

The 11 valid species of hammerhead sharks come in different shapes and sizes, but they all have something in common: a wide head with eyes on the ends. In one species, winghead sharks, the head is half as wide as the body is long! Hammerheads are deadly hunters. They use their sixth sense, electroreception, to detect the electricity all living things give off. That helps them find prey hiding in the sand.

Stats

Family: Sphyrnidae
Pronunciation: SFUR-na-dee
Meaning: “hammer”
Species: Eusphyra blochii, Sphyrna corona, Sphyrna gilberti, Sphyrna lewini, Sphyrna media, Sphyrna mokarran, Sphyrna tiburo, Sphyrna tudes, Sphyrna zygaena
Size: 3–20 feet
Weight: 24–1,300 pounds
Habitat: tropical and temperate coastal waters
Food: other fishes as well as invertebrates like jellyfishes, crabs, and octopuses
Cool fact: Their wide head is called a cephalofoil, which means “winged head.”
Eco fact: Hammerhead populations are declining, and most species are listed as Critically Endangered, Endangered, or Vulnerable.

Stumper

What’s so great about having a super-wide head?

It gives hammerheads a panoramic view of the sea around them

The larger surface area allows for more electroreceptors

Both of the above

Correct!

Wide heads are helpful in so many ways! They help hammerheads scan wider areas of the seafloor for electrical impulses. And hammerheads can use them to pin stingrays down on the seafloor and chomp on their winglike fins.

Stumper

How do great hammerhead sharks (the largest hammerhead species) cool down in the summer?

They wave their heads to get water currents moving

They migrate

They bury themselves in sand

Correct!

In the summer, schools of great hammerheads migrate to cooler waters.

Fact or Fiction

Baby hammerhead sharks have bellybuttons.

Fact

Fiction

Fact

Hammerhead shark mothers nurture their young inside their bodies. There the growing pups get their nutrients through a placental connection similar to an umbilical cord in humans! That means babies have bellybuttons—at least for a few months, until they fade.

Fact or Fiction

Hammerheads evolved before most other sharks.

Fact

Fiction

IchthyOlogists think hammerhead sharks may have evolved only 23 million years ago! That makes them a relatively recent shark group (or family).

Fact or Fiction

Some hammerheads are born with their heads folded up.

Fact

Fiction

Fact

Winghead sharks have the widest heads of all. They grow inside their mothers with the sides of their heads folded back against their bodies. Once they’re born, their heads unfold!