Hammerhead sharks are one of the easiest sharks to identify, thanks to their hammer-shaped heads, and are a great species of shark to dive with. They can be found at a variety of top dive destinations including Cocos Island off Costa Rica, Malepelo Island in Colombia, and the Galápagos Islands. Divers can also enjoy hammerhead encounters while scuba diving Rasdhoo Atoll in the Maldives, Lombok in Indonesia, French Polynesia, the Red Sea and Egypt, the Bahamas, and Morovo Lagoon in the Solomon Islands.

Most divers are aware of the great hammerhead and the scalloped hammerhead sharks but there are actually a nine known species around the globe, ranging from less than one metre to six metres in size. Five of the hammerhead species are vulnerable to extinction or classified as endangered due to overfishing for the shark fin trade: the winghead shark, scalloped hammerhead, great hammerhead, smalleye and smooth hammerhead sharks.

Great Hammerhead (Sphyrna mokarran)

The great hammerhead is the largest species in the family (Photo: WayneWorks Marine/Aggressor Fleet)

True to its name, the great hammerhead is the largest of the hammerhead sharks. They grow to a maximum length of around six metres and are found in coastal areas and offshore in both temperate and tropical waters. They can be identified by their large hammer, or cephalofoil, and huge dorsal fin. One of their favourite prey items are stingrays, though they eat a variety of prey, and they have litters of up to 50 pups at a time. Great hammerheads tend to be solitary swimmers.

This shark species has been heavily fished due to its large dorsal fin and great hammerheads are endangered. Divers can see this magnificent predator at various locations, including at the Bahamas and Coiba Island in Panama.

IUCN Status: ENDANGERED

Scalloped Hammerhead (Sphyrna lewini)

The scalloped hammerhead is probably the most frequently encountered by divers around the world (Photo: WayneWorks Marine/Aggressor Fleet)

This relatively large hammerhead shark can grow to three metres in length and is recognisable by the notches in its hammer, which resemble the shape of a scallop shell. These sharks sometimes venture into estuaries and are found in warm temperate and tropical waters across the globe. 

Young scalloped hammerhead sharks are known to use estuarine areas around Fiji during their early years. Considered to be endangered throughout their global distribution, the recent discovery of these aggregation areas is important in helping ensure the survival of these sharks. 

Divers can enjoy encounters with schooling scalloped hammerhead sharks while scuba diving Cocos Island, Costa Rica. 

IUCN Status: ENDANGERED

Smooth Hammerhead (Sphyrna zygaena)

Smooth hammerhead (Photo: Alessandro De Maddalena/Shutterstock)

The smooth hammerhead doesn’t have an indentation in the centre of its hammer, giving it a smooth appearance, and these sharks are more tolerant of cooler waters than other hammerheads. They are found in temperate and warmer waters around the globe and they migrate to the poles during the summer to stay cool. They are the second largest hammerhead shark after the great hammerhead and feed on bony fishes – but will also feed on other sharks and rays. They stay closer to the ocean surface than scalloped and great hammerheads and prefer to spend time in bays and estuaries. As a result, smooth hammerheads have been heavily overfished.

IUCN Status: VULNERABLE

Winghead Shark (Eusphyra blochii)

X-Ray of the winghead shark showing the wide extent of its cephalofoil (Photo: Sandra Raredon/Smithsonian Institution)

This small species of hammerhead, growing up to two metres in length, has a very large hammer as wide as 50 per cent of the shark’s length. They are found in tropical waters of the central and western Indo-Pacific and feed mostly on bony fishes. They have litters of up to 25 pups at a time and have been heavily fished for their meat and fins. 

IUCN Status: ENDANGERED

Bonnethead (Sphyrna tiburo)

Bonnethead resting in the sand (Photo: IrinaK/Shutterstock)

This small and active hammerhead shark has a distinctive rounded head and is sometimes called the shovelhead. Males and females of this species have different shaped heads, which is unique to this hammerhead species. The adult females have broad round heads, whereas males have a distinctive bulge in the middle of the hammer. 

These sharks have a small hammer compared to other hammerheads and have to rely upon their large pectoral fins for swimming. Compared to other hammerheads, they have larger pectoral fins as a result and are the only hammerhead to use their pectoral fins for swimming. 

IUCN Status: LEAST CONCERN

Scalloped bonnethead (Sphyrna corona)

Scalloped bonnethead (Photo: D Ross Robertson/Wikimedia Commons)

This is a rare species of shark, relatively unknown, and sometimes called the crown shark or mallethead shark. It is found in the eastern Pacific Ocean and has a limited range from Mexico to Peru. These sharks spend their time inshore, sometimes visiting estuaries and mangroves, and feed on fish and crustaceans.

This small shark, growing up to just 1m in length, has a distinctive rounded head similar to the bonnethead shark. They only have two pups per litter, which are born at just 23cm length. 

IUCN Status: NEAR THREATENED

Scoophead (Sphyrna media)

Scoophead (Photo: D Ross RobertsonD Ross Robertson/Wikimedia Commons)

The scoophead is another species of hammerhead that few people know about and is found in tropical waters in the Western Atlantic and Eastern Pacific oceans. It is slightly larger than the scalloped bonnethead but at first glance, they appear similar. The scoophead shark has a shorter snout and broad arched mouth.

This shark can be found living alongside bonnethead and smalleye hammerheads off the coast of Trinidad, where it feeds on octopus, smaller sharks, squid and flounders. Little is known about this species of sharks, but it is caught by fisheries throughout its range.

IUCN Status: DATA DEFICIENT

Smalleye hammerhead (Sphyrna tudes)

Smalleye hammerhead, also known as the curry shark. (Photo: manimalworld.net/Wikimedia Commons CC BY-SA 3.0)

Smalleye hammerheads have a unique bright gold colour on their heads and parts of their body and are sometimes called golden hammerheads or curry sharks. It is thought the colouration comes from pigment in the shrimps that juvenile smallhead sharks eat and from the sea catfish that adults eat. This distinctive colour may help camouflage them in the muddy habitats they prefer, making it difficult for larger predators to find and hunt them.

They are commonly found in shallow waters off Venezuela to Uruguay and have litters of up to 19 pups each year. They are caught by fisheries throughout their range and their numbers are declining, making them vulnerable to extinction.

IUCN Status: VULNERABLE

Carolina hammerhead (Sphyrna gilberti)

The first specimen of the Carolina hammerhead to have been recorded was in 1967, however, it wasn’t formally described as a separate species until 2013. Its appearance is almost identical to the scalloped hammerhead but the Carolina hammerhead has 10 fewer vertebrae and is genetically distinct. Little research has been conducted into this shark and therefore there is no current data available on the conservation status of this species.

IUCN Status: YET TO BE ASSESSED

Source:  divemagazine.co.uk