Recognized easily by their unique head shape, hammerhead sharks are commonly found throughout the world in mostly tropical waters. A total of nine unique species are categorized under the hammerhead name, and each of them can be easily identified by specific traits and habits. Many of these majestic predators are critically endangered and face extinction if they are not carefully managed going forward. Despite few reports of hammerhead attacks on humans, they’re often captured in fishing nets that lead to their untimely demise.

Species Background

The distinguishing feature of a hammerhead shark is their flat, oblong-shaped head. This mallet shape is often known as a cephalofoil, and the shape varies in hammerhead species. Whether it’s rounded or square depending on the shark, the cephalofoil automatically shows that the shark in question is a hammerhead. Unlike some other shark variations, hammerhead sharks typically school in shallow water, and because of this they can get tanned from sun exposure when they’re too close to the surface.

Although size sometimes varies, hammerhead sharks grow to be anywhere from 13 to 20 feet long as adults, weighing between 500 to 1000 pounds in total. Hammerhead habitat varies between tropical and temperate climates worldwide, and warming waters often see mass hammerhead migrations to cooler areas. Certain species can be considered deep water swimmers up to 300 meters, although this depends on specific features like habitat, hunting patterns and migration routes.

Ampullae of Lorenzini

Senses are crucial for hammerheads to be able to hunt and navigate effectively. Sensory organs called ampullae of Lorenzini are distributed across the elongated head of hammerhead sharks, and they add an extra boost to their already honed senses. Originally named after Italian scientist Stefano Lorenzini, the function of these ear-like pores was a mystery upon his initial discovery in the 17th century. The use of these receptors was only identified in 1960, when they were recognized as specialized receptors for electric current.

Part of the lateral line system, these ampullae offer the ability to detect muscle contractions of potential prey. Any muscle contraction, even a heartbeat, can trigger these receptors. The hammerhead has ampullae of Lorenzini spread widely over their head, allowing them to more easily hunt for food along the ocean floor. This special feature is visually noticed via small pores across the head of the shark, and each of these pores contains tiny hairs and a fluid chamber (ampulla) with nerve cells to detect these pulses.

Although these receptors are beneficial for hammerhead sharks, they only fire when the shark is within a few inches of their prey. This feature is what makes hunting buried stingrays so easy for hammerheads, since they only have to get close for these movements to become apparent. For other prey, it helps hammerheads keep their eye on the prize when evasive maneuvers come into play.

Ampullae of Lorenzini are often used to tune into Earth’s magnetic field, so these special receptors are used for migration and homing in addition to hunting.

What is so special about hammerhead sharks?

The main feature that makes hammerhead sharks unique among other shark species is their uniquely-shaped head. Much of the body is the same as other species, but the “hammer” head is flat with eyes situated on either side. These spaced-out eyes give hammerheads a full 360-degree view of their area so they can be more aware of prey they’re trying to hunt. However, the area directly in front of a hammerhead is a complete blind spot, and that can be a problem in some situations. Their dorsal fins are also a stand-out feature, since they are quite tall and pointy compared to some other species.

Since there are nine different species of hammerheads that exist in the wild, relative size varies depending on the shark. The largest of these species is the great hammerhead (Sphyrna mokarran) which is most commonly the poster child for all hammerhead varieties. This aquatic beast usually ranges anywhere between 15 to 20 feet in length and features an elongated, boxy head shape.

Will hammerhead sharks go extinct?

Unfortunately, extinction is a possibility for most species of hammerhead shark. Overfishing has led populations to drastically decrease, and since hammerheads do not usually have many young, they are not able to make up for this shortage. The scalloped hammerhead is speculated to have lost upwards of 80% of their previous population around the waters of Queensland, Australia alone, and that’s data from just one specific area.

The great hammerhead, as well as the scalloped bonnethead, smalleye hammerhead, scalloped hammerhead and scoophead hammerhead, are all critically endangered worldwide according to IUCN’s Red List. Some experts believe there may be as few as 200 great hammerhead sharks left in the entire ocean, so extinction is a very real risk for these apex predators. Winghead and bonnethead hammerhead sharks are listed as endangered, which still puts them at a relatively high risk compared to most other sea life.

As of 2021, the smooth hammerhead is the only species of hammerhead shark deemed as vulnerable. All of these predators are key to having a balanced ocean food web, so a decrease in fishing these creatures is essential to ensure they don’t go extinct in the next century.

How long do hammerhead sharks live?

Generally, hammerhead sharks can live anywhere from 20 to 30 years depending on their habits. Some of this has to do with how much they are able to evade humans, who are their greatest predator to date.

Hammerheads have a distinct fin that sets them apart from other shark species because of its height. Interested in only the fin or other desirable parts, humans will often capture the hammerhead, take their fin, and throw them back into the ocean. This leaves the hammerhead shark with little ability to swim and navigate as a result, so this abusive practice usually leads to their demise.

Hammerhead sharks are also sought out for their meat, liver oil, hides and carcasses. Although they aren’t usually targeted by fisheries directly, seizure and slaughter usually occurs by unintentional capture in fishing nets. Estimates show that only about 2/10 sharks captured will be thrown back alive, leading to untimely death even when no meaningful harm is done to the shark.

What fish do hammerheads eat?

Hammerhead sharks are fond of sweeping the ocean floor for their prey. Since their eyes are located on either side of their elongated head, scanning this way is their preferred method of hunting. Of all the oceanic creatures they’re known to eat, hammerheads usually prefer to hunt stingrays that often hide under a layer of sand on the ocean floor. However, they’ll just as easily go after other ocean floor dwellers such as squids, crustaceans, octopi and even other sharks.

There is evidence that great hammerhead sharks specifically are cannibalistic, and sometimes will eat their own species for reasons unknown. As such, great hammerheads also are not preyed upon by any other species, leaving them to potentially attack other individuals that put them at risk.

Do hammerhead sharks attack humans?

Among the nine different species of hammerhead, most are considered harmless. Even though there aren’t many recorded attacks, the great hammerhead may be considered more dangerous out of the hammerhead varieties because of their larger size. Great white sharks, tiger sharks and bull sharks are the three species most commonly blamed for shark attacks on humans. While the chances of getting attacked by a hammerhead shark aren’t zero, the proven risk is nowhere near as high as the three species above.

Hammerhead sharks have proven their worth as incomparable apex predators, and yet they’re known to be a critically endangered species among sea life. Overfishing is largely to blame for this shortage of hammerheads, and the major solution is to change fishing practices to not threaten this fragile species. It will be interesting to see whether or not the planet at large is willing to change their ways to save these exceptional hunters of the sea.

Works Cited

Brezina, V. (2017, March 30). 7 Things You Didn’t Know About Hammerhead Sharks. SportDiver. Retrieved December 10, 2021, from https://www.sportdiver.com/photos/7-things-you-didnt-know-about-hammerheads#page-3

No author or date specified. Hammerhead Shark. National Geographic Animals. Retrieved December 10, 2021, from https://www.nationalgeographic.com/animals/fish/facts/hammerhead-sharks.

No author or date specified. Great Hammerhead Sharks, Sphyrna mokarran. Marine Bio. Retrieved December 13, 2021, from https://www.marinebio.org/species/great-hammerhead-sharks/sphyrna-mokarran/.

No author or date specified. Hammerhead Sharks. Australian Marine Conservation Society. Retrieved December 13, 2021, from https://www.marineconservation.org.au/hammerhead-sharks/.

No author or date specified. Hammerhead species search. IUCN Red List of Threatened Species. Retrieved December 13, 2021, from https://www.iucnredlist.org/search?query=hammerhead&searchType=species.

Zug, G. (2018, May 03). Lateral line system. Encyclopedia Britannica. Retrieved December 13, 2021, from https://www.britannica.com/science/lateral-line-system.

Benningfield, D. (2011, May 01). Ampullae of Lorenzini. Science and the Sea. Retrieved December 13, 2021, from https://www.scienceandthesea.org/program/201105/ampullae-lorenzini.