November Elasmobranch of the Month: Smooth Hammerhead Shark
Smooth Hammerhead Shark
We’ll bet you’ll recognize this iconic shark just by the shape of the head!
Key Features & Appearance
It’s hard to forget the sight of a smooth hammerhead shark. One of their most distinctive features is their rounded head, which extends outwards in a cephalofoil shape. This unique structure allows smooth hammerheads to quickly maneuver through the ocean and more effectively hunt for prey.
Being particularly large sharks, smooth hammerheads can grow up to 16.4 feet long and can weigh up to 880 pounds. They tend to have a dark coloring, such as a dark olive or a dark brown-gray. Unlike other hammerheads, smooth hammerheads do not have a mid-dorsal fin, adding to their “smooth” appearance.
Habitat & Distribution
Smooth hammerhead sharks live worldwide in both temperate and tropical waters. They are typically found near coasts and inshore waters, including bays and estuaries. Generally, they prefer shallow waters of less than 65 feet, though they have been seen in depths of 656 feet.
A smooth hammerhead’s diet consists of bony fish, skates, rays, dolphins, crustaceans, cephalopods, and even smaller smooth hammerheads. As active predators, they are equipped with an ideal hunting tool: their hammer-shaped heads. Smooth hammerheads often use their heads to pin down their prey, such as stingrays—their favorite food!
As viviparous sharks, female smooth hammerheads give birth to live young. In fact, a single litter can consist of 29 to 53 pups! Smooth hammerheads raise their young in nurseries within shallow waters, which are typically less than 33 feet deep.
Besides an occasional orca, adult smooth hammerheads have no natural predators. However, juveniles are vulnerable to attacks from adult sharks, including their own species.
Overfishing is another major threat to smooth hammerheads. As coastal sharks, they are particularly vulnerable to becoming victims of bycatch. They are also one of the most common targets of the shark fin trade. In some cases, smooth hammerheads are even hunted for their liver oil, which is rich in Vitamin A.
According to the International Union for Conservation of Nature (IUCN), smooth hammerhead sharks are currently “Vulnerable.” Though certain populations are overfished, their high reproduction rate has protected many populations from reaching an “Endangered” status yet.
Did you know that smooth hammerhead sharks have a near 360 degrees of vision? Compared to other shark species, their head structure provides them with exceptional eyesight. These sharks only have one blind spot—right in front of their snouts!
“The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species, www.iucnredlist.org/. Accessed 16 Nov. 2023.
“Smooth Hammerhead - Sphyrna Zygaena.” Shark Research Institute, www.sharks.org/smooth-hammerhead-sphyrna-zygaena.
“Smooth Hammerhead Shark.” Oceana, 27 June 2023, oceana.org/marine-life/smooth-hammerhead-shark/.
“Smooth Hammerhead Shark.” Virginia Institute of Marine Science, www.vims.edu/research/units/programs/multispecies_fisheries_research/sharks/species/smooth_hammerhead.php.
“Species: Sphyrna Zygaena, Smooth Hammerhead, Smooth Hammerhead Shark.” Shorefishes - The Fishes - Species, biogeodb.stri.si.edu/caribbean/en/thefishes/species/118.
“Sphyrna Zygaena.” Discover Fishes, www.floridamuseum.ufl.edu/discover-fish/species-profiles/sphyrna-zygaena/.
Yong, Ed. “Widely Set Eyes Give Hammerhead Sharks Exceptional Binocular Vision.” Science, National Geographic, 3 May 2021, www.nationalgeographic.com/science/article/widely-set-eyes-give-hammerhead-sharks-exceptional-binocular-vision.