Hammerhead Shark Facts Q & A

Hammerhead Shark Facts Q & A

 

Hammerhead Shark Facts Q & A

Great_hammerhead_shark
Great hammerhead by Albert kok cc4.0

Sharks are fishes with leathery skin, large dorsal fins – that triangular thing you see above the water’s surface – sharp teeth and fierce appetites. Most of them have pointed or rounded snouts as well, but not the hammerhead shark. Its head is long and spread out horizontally just like a hammer. That’s how it got its name. But why does it have such a weird-looking head? Doesn’t that make it hard for the shark to see? Let’s find out the answers to the most common questions about the hammerhead shark below.


Q: Why do hammerhead sharks have a hammerhead?

hammerhead_shark_vision
Image credit: zanthrax-dot-nl cc2.0

A: For a long time, even scientists couldn’t understand why the hammerhead shark looks the way it does. Some said it was to help it swim. Others said it was to trap prey. Still others said that the hammerhead provided the shark with excellent vision, though some doubted it. How could you see well when your eyes were so far apart?

Recently, though, it has been proven that the unique shape of the hammerhead shark’s head does give it excellent vision. It can use both eyes together to see complete images. It even has 360-degree vision, which means it can see above, below, in front and behind it at all times! This makes the hammerhead shark’s vision better than other sharks.


awesome shark


Q: Where do hammerhead sharks live?

Sphyrnidae_distribution_map
Distribution map of hammerhead sharks (Family: Sphyrnidae) by Canuckguy PD image

A: Hammerhead sharks can be found in warm waters all over the world, both near and far from the shore. Sometimes, they can be found in groups called schools, with hundreds of sharks.


Q: How big are hammerhead sharks?

Great_hammerhead_shark
Great hammerhead by Albert kok cc4.0

A: There are nine known species of hammerhead sharks. Of them, the biggest is the great hammerhead shark, which can grow to 11.5 feet and weighs over 500 pounds on average. The longest great hammerhead shark ever caught was 20 feet long – that’s as long as two average limousines – and the heaviest on record weighed more than 1,200 pounds, as heavy as a young rhino. That’s because it was a pregnant female with 55 pups inside her!

The smallest hammerhead shark is the scalloped bonnethead shark which grows 2 to 3 feet on average.


Q: What adaptations do hammerhead sharks have?

Electroreceptors_in_a_sharks_head
Electroreceptors in a sharks head, including Ampullae of Lorenzini and Lateral Line canals. By Chris_huh image

A: If you’re wondering how hammerhead sharks adapt to their environment, there are several ways. Their colouring itself is an adaptation. They are darker on top, either greenish or bluish grey, which makes them hard to see from above, but they are white on the bottom, which also makes them hard to see from below, especially against the bright sunlight.

Like most sharks, hammerhead sharks hunt at night when most of the sea creatures are asleep, though they will eat whenever they come across an easy meal. Like other sharks, they also have a keen sense of smell and the ampullae of Lorenzini, which are pores that sense the electric fields in the water. Every living creature has an electric field and by sensing this, the shark can easily find prey. This is particularly easy for the hammerhead shark because its pores are widely distributed over its broad head.

Also, hammerhead sharks have a thin, streamlined body that allows them to swim efficiently. Sometimes, they can even use their heads to steer.


Q: What do hammerhead sharks eat?

Stingray
Stingray by petersbar cc2.0

A: A hammerhead shark’s diet consists of stingrays, fishes, squids, octopuses and crustaceans. Larger hammerhead sharks also feed on smaller sharks, even those of their own kind. Great hammerhead sharks will even eat their own young if food is scarce.

Hammerhead sharks particularly love to eat stingrays. They swim along the bottom of the ocean, searching for these tasty treats. With their excellent vision, they can find the rays even when they are buried under the sand. They swoop down, pinning down the ray with their heads, then they start eating it while it is weak and helpless.


Q: Do hammerhead sharks lay eggs?

viviparous_sharks_hammerhead_shark
Viviparous Sharks. A hammerhead female with 15 well-developed pups which were removed from the uterus. Image credit: D. Perrine

A: Some sharks are oviparous which means they lay eggs like birds. Others are viviparous which means they give birth to live young ones just like dogs, cats and humans do.

Which group do hammerhead sharks belong to? They are among the viviparous sharks. They have babies, which are called pups. The smallest hammerhead sharks, the scalloped bonnetheads, have only two pups after a few weeks of gestation. Medium-sized hammerhead shark species can have 12 to 15 pups after a few months, while the great hammerhead shark can have 20 to 40 pups, the largest litter on record being 55 pups. Female great hammerhead sharks are pregnant for 8 to 11 months. Regardless of the species, all females swim away after giving birth, not providing the babies with any care in any way. Young hammerhead sharks can swim and hunt from the moment they are born, eating mostly fish and crustaceans.


Q: How long do hammerhead sharks live?

Bonnethead_Shark
Bonnethead shark (Sphyrna tiburo) at the Texas State Aquarium. Image credit: Matt Howry cc2.0

A: As with most mammals, larger hammerhead shark species live longer than smaller ones. Great hammerhead sharks can live for 20 to 30 years while bonnethead sharks live only 10 to 12 years.


Q: Do hammerhead sharks attack people?

Scalloped_hammerhead
Scalloped hammerheads (Sphyrna lewini) off Cocos Island, Costa Rica. Image credit: Barry Peters cc2.0

A: Since 1580 up until 2014, only 17 unprovoked attacks by hammerhead sharks have been reported and none of these were fatal. Compare that to the 279 recorded attacks by great white sharks, 78 of which ended up becoming deadly, and you will see how the hammerhead shark is not much of a threat. Besides, of all the species of hammerhead sharks, only three have been known to attack humans – the great hammerhead shark, the smooth hammerhead shark and the scalloped hammerhead shark, though the scalloped hammerhead shark is usually not aggressive.

Indeed, if you’re wondering, ‘Are hammerhead sharks aggressive?’ The answer is: Usually, no. Only the great hammerhead shark is known for being aggressive. Most hammerhead sharks are shy or do not pay attention to humans, only attacking when hungry or disturbed.




Q: Are hammerhead sharks endangered? Why?

Shark Fin Soup - Gold Leaf Burwood
Shark Fin Soup by avlxyz cc2.0

A: Of the nine species of hammerhead sharks, two are classified as endangered – the great hammerhead shark and the scalloped hammerhead shark. Two are classified as vulnerable, which means their population is decreasing – the smooth hammerhead shark and the smalleye hammerhead shark. The rest have fairly stable populations. For now.

Why are some hammerhead sharks in danger of becoming extinct? This is because they are regularly caught, not for their meat, which is not considered tasty, but for their fins that are used to make shark fin soup, an expensive Asian delicacy. Their skin is also used to make leather and their liver oil used for medicinal purposes.


The YouTube video below contains a playlist of 3 videos about hammerhead Sharks. The list of videos featured is underneath.

Click to go back to the book page and video list…
Sharks Early Readers or Sharks! Books

The Playlist:

  1. Hammerhead shark evolution – BBC – A look at how the hammerhead’s strange head came about.
  2. Gatherings of Hammerhead sharks in Costa Rica – BBC Earth – Kim Holland discusses the huge crowds of Hammerhead sharks seen in this BBC footage.
  3. World’s Deadliest : Hammerhead Sharks by NatGeoWild

Sources:

http://en.wikipedia.org/wiki/Hammerhead_shark
http://www.sharks-world.com/hammerhead_shark/
http://animals.howstuffworks.com/fish/sharks/hammerhead-shark2.htm
http://animals.nationalgeographic.com/animals/fish/hammerhead-shark/

To view the complete list of sources, please click here.

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