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 at 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, Egypt, the Bahamas, and Morovo Lagoon in the Solomon Islands.
Most divers are aware of great hammerhead and scalloped hammerhead sharks but there are actually a variety of hammerhead shark species around the globe, ranging from one 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.
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.
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. The M/V Okeanos Aggressor offers year-round diving cruises to Cocos Island.
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.
The smooth hammerhead is listed as vulnerable to extinction and has been heavily overfished.
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. They are listed as endangered by the IUCN.
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.
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. This rare shark is near threatened with extinction.
The scoophead shark 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.
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.
This shark species was only described in 2013 and is found off the coast of South Carolina. It looks almost identical to the scalloped hammerhead but has 10 fewer vertebrae and is genetically distinct.
This article was written by divers and writers at LiveAboard.com
‘Sanctuaries Not Tanks’ campaign calls for an end to the exploitation of captive dolphins, whales and porpoises
Born Free is highlighting the plight of dolphins, whales and porpoises (collectively known as cetaceans) kept in captivity this Dolphin Awareness Month by calling on governments and the travel industry to end cetacean exploitation for entertainment purposes and to advocate the creation of dolphin sanctuaries.
Born Free first exposed the plight of captive dolphins more than 30 years ago. Since then, Born Free has contributed to the closure of the last dolphinaria in the UK, rescued and rehabilitated two bottlenose dolphins and ensured their release back into the wild, and co-founded the World Cetacean Alliance and the Dolphinaria-Free Europe coalition.
Samantha Goddard, Programmes Officer at Born Free Foundation, said: “This month, Born Free will challenge the claims made by the captive dolphin industry, highlight the plight of these intelligent and social marine mammals and expose the truths about dolphin captivity. Our Sanctuaries Not Tanks campaign aims to influence and encourage an end to the exploitation of cetaceans for entertainment purposes, whilst ensuring animals currently in captivity are housed in improved conditions.”
Using a striking image designed by George Logan (above) and promoting an animated #Stop Dolphinaria film, Sanctuaries Not Tanks aims to:
• Promote the truth behind captive cetacean facilities through the #StopDolphinaria film
• Provide the scientific evidence that confirms cetaceans suffer in tanks
• Question the compliance of the captive cetacean facilities with legislative requirements
• Urge governments to phase-out the keeping of cetaceans in captivity
• Encourage tour operators to no longer promote captive dolphin facilities where cetaceans will be used for theatrical, contact or other entertainment purposes
• Advocate the solutions by supporting the creation of seaside sanctuaries and species conservation in the wild.
On 20th February 2017, tour operator Virgin Holidays announced a new position on cetacean captivity. It said that existing captive animal attractions that keep cetaceans for entertainment purposes would need to change their practices to reflect changing consumer tastes, whilst new facilities would not be contracted. Born Free welcomed the announcement, particularly because Virgin Holidays now advocates the creation of coastal sanctuaries for whales and dolphins and the conservation of species in the wild.
Daniel Turner, Associate Director for Tourism at Born Free said: “Our Sanctuaries Not Tanks campaign aims to influence and encourage other tour operators which promote the captive cetacean facilities to the public to follow Virgin Holiday’s lead. The scientific evidence is conclusive: whales and dolphins suffer both mentally and physically from restrictive space and barren environments; commonplace in captivity. Travel businesses can no longer ignore these facts and they must cease to promote the facilities where cetaceans will be used for theatrical, contact or other entertainment purposes.”
Born Free Foundation President, Will Travers OBE, added: “The days of keeping such incredible creatures in captivity are numbered. This Dolphin Awareness Month I urge and encourage members of the public to support our endeavours in securing a future where wild cetaceans can thrive in their natural habitat for generations to come.”
Members of the public can support Sanctuaries Not Tanks by:
• Making a pledge to not visit dolphinaria or swim with captive dolphins
• Joining Born Free’s Team POD
• Making a donation to the Sanctuaries Not Tanks campaign
• Adopting Muddy the dolphin
• Adopting Springer the orca.
Sanctuaries Not Tanks campaign: http://www.bornfree.org.uk/campaigns/zoo-check/captive-whales-dolphins/tanksnothanks/
Dolphin Awareness Month runs from 1st-31st March 2017.