Hammerhead Shark

The hammerhead shark is a carnivore, a predator that feeds on meat. It has developed specific methods for feeding to hunt prey effectively. The “hammer” shaped head of the Hammerhead Shark enables it to pin stingrays, skates, and other ray species to the seafloor, allowing it to deliver a highly accurate bite (a method few other species of sharks are capable of).

Some examples of the food eaten by a hammerhead shark include:

• Fish with a hard skeleton (such as Groupers, Catfish, Sardines)
• Cephalopods (including Squid, Octopus)
• Crustaceans (such as Crabs and Shrimp)
• Rare instances of Hammerhead Sharks eating each other (cannibalism)

Hammerheads tend to feed in shallower water and travel to bays and estuaries during certain periods of time. The shape of the hammerhead’s head provides enhanced electroreception, which allows it to locate the electrical signals from its prey buried under the sand or sediment.

Safety remains the primary concern when sharks are encountered during diving activities and this applies to the hammerhead shark as well.

According to National Geographic, hammerhead sharks do not actively hunt humans and are generally considered non-aggressive. Research indicates that hammerhead sharks (genus Sphyrna) rarely attack humans without provocation.

Despite its large size, the Great Hammerhead Shark typically shows little interest in human interaction during most observed encounters. When incidents do occur, they are usually linked to defensive behaviour rather than predatory intent.

Divers can minimise risk by respecting the hammerhead shark’s space, avoiding sudden movements, and following the guidance of experienced dive operators. Calm behaviour and awareness are key to ensuring safe and responsible interactions when diving in hammerhead shark habitats.

A significant aspect of the agility demonstrated by the hammerhead shark is the way it swims. While hammerhead sharks can reach an approximate top speed of 25 mph (40 km/h), for very short periods, this is not sufficient to classify them as among the fastest swimmers in the shark family.

The swimming abilities of juvenile scalloped hammerheads were evaluated in research using controlled flume tests at 1.17 body length/second. This was intended to highlight their swimming efficiency rather than their pure speed.

Research has identified that the cephalofoil of the hammerhead provides additional hydrodynamic lift and enhances the stability of its swimming motion. The cephalofoil increases the shark’s manoeuvrability while reducing the energy required to generate a swimming motion. Additionally, studies have shown that hammerhead sharks spend approximately 90% of their swimming time with a slight roll to the left or right of their body; this reduces drag while maintaining lift.

Although the hammerhead may not be one of the fastest swimmers in the ocean, its ability to swim efficiently, find food such as stingrays along the ocean floor, and navigate from one area of the reef zone to another make it an excellent and specialised swimmer.

Understanding the hammerhead shark’s life cycle will enable researchers to assess its development and reproduction and determine whether it is likely to be threatened or endangered. The majority of hammerheads are estimated to live approximately 20-30 years in the wild.

Research on age analysis indicates that larger female great hammerheads may live for 40 to 44 years, placing them among the longest-living shark species.

Hammerhead sharks mature sexually much later than most other sharks, which increases the likelihood that they will experience population declines.

Because of the combination of the long life span of the hammerhead shark, along with delayed reproduction and the low reproductive rate of the species, it is difficult for the species to recover from losses of the population resulting from overfishing and bycatch. These biological characteristics significantly contribute to the current and ongoing conservation threats faced by many species of hammerheads.

Hammerhead sharks are among the most endangered shark species, with several species being considered critically endangered and at a very high risk of extinction.

The IUCN lists the scalloped hammerhead as Critically Endangered, indicating that there is an extremely high risk of extinction in the wild. Similarly, the great hammerhead (Sphyrna mokarran) has had a greater than 80% decline in populations in certain areas, resulting in a Critically Endangered listing.

Additionally, several species within the hammerhead shark family have been classified as Vulnerable, Endangered or Critically Endangered, showing a need for conservation actions across the entire family.

The main threats to hammerhead sharks are:

• Shark Fin Trade: The value placed on hammerhead fins makes them prime candidates for the fin trade, putting many of them at high risk of overfishing.
• Fishing Pressure: Hammerheads are regularly captured by commercial fisheries using gillnets, longlines and other types of commercial fishing gear; whether they are intended to be captured (targeted) or accidentally captured (bycatch).
• Habitat Destruction: Coastal habitat loss due to coastal development can destroy the nurseries for juvenile hammerhead sharks, which reduces their ability to survive and grow into adults.
• Each hammerhead shark sighting in the wild is a population under stress. It will take significant conservation action, sustainable fishing practices and support from the public to help ensure the continued existence of this species.

For those who are interested in marine adventures like shark diving, it is essential to know some basic information on how to stay safe before getting into the water. The chance of an adverse human-shark encounter with a hammerhead shark is very small. Since 1580, only 17 unprovoked hammerhead shark attacks have been documented worldwide, with no recorded human fatalities.

Further reducing this risk is adherence to established safety practices when diving with hammerhead sharks; these include staying calm and not making sudden movements or excessive splashing while in the water. Divers should also listen to the advice of their dive guides and never use a speargun in the same waters where they will be interacting with wild hammerhead sharks. Wild animals, no matter how predictable they may seem, cannot always be predicted. Acting responsibly is paramount for ensuring safe interactions with wild animals.

A combination of a professional guide and established safety protocols makes for a safe and enjoyable experience of shark diving with large predators. Most reputable shark diving operators provide education on hammerhead shark behaviour, which includes information about movement patterns, distance to keep from the shark, use of camera lights, and how to properly interact with them to create safe and respectful experiences.

The widespread impacts of the conservation status of the hammerhead shark are evident in its position as a top predator in marine ecosystems. As a top predator, the hammerhead shark regulates the population levels of rays and other prey, thereby limiting the potential for overgrazing and disturbance of benthic habitats (such as seagrass beds and coral reefs) that these prey species might cause.

The reduction in hammerhead shark populations can have ripple effects throughout an entire ecosystem; when a predator is removed, prey populations can grow unchecked, leading to long-term habitat degradation.

In addition to their ecological importance, hammerhead sharks also contribute significantly to marine biological research. The unique structure of their body and behaviours of the hammerhead shark allow scientists to gain insights into how sensory systems function, cephalofoil evolution occurred, hydrodynamics works and how schooling behaviour develops. Because of these contributions to our understanding of shark biology and ocean ecology, the hammerhead shark will remain an important species for scientific advancement in these fields.

The hammerhead shark continues to capture our interest because of its distinctive cephalofoil structure and its growing vulnerability to human activity. Any ocean adventure involving these sharks should balance excitement with environmental responsibility, encouraging respectful observation and support for conservation-focused operators.

Our Durban marine adventure invites you to experience shark diving in a way that builds a deeper connection with the ocean and helps protect these remarkable mallet-headed predators for future generations.