Updated: Sep 16, 2019
Common name: Scalloped Hammerhead
Scientific name: Sphyrna lewini
Size: Average Size at sexual maturity 1.4-4.3m
Weight: Up to approx. 150kg
Lifespan: Up to 35years
IUCN Red List Status: Endangered
Diet: Favourite foods are Squid and stingrays; also sardines, barracuda, parrotfish, ray-finned fish and sometimes small blacktip reef sharks
Divine Feminine was inspired by my time spent diving with Scalloped Hammerheads in Cocos Island, Costa Rica. Of all shark species, Scalloped Hammerheads have some of the largest brains in comparison to their body weight. During the day they school together at Cocos island’s seamounts by the hundreds, not to hunt but to socialise. By night, they become solitary hunters. I remember one of my first hammerhead dives in Cocos Island was at ‘Manuelita Outside’ where there are three very distinct cleaning stations and so there is a thriving hotspot with a near-constant flow of sharks.
‘Manuelita Outside’ is one of the favourite locations at Cocos Island and is known for epic shark dives. Here I dived into the murky blue grey water where I hit a rocky volcanic wall covered in sea urchins, algae, barnacles and some hard corals. This dive had a crazy surge, the strongest I had experienced, and the swell pushed you up and down around 3-5 metres. In Cocos, you tend to find the wildest conditions bring the most life. At first the visibility was poor but as we slowly drifted around the craggy walls to shelter from the surge, the water started to clear and we settled down. I wedged my fins into some rocks to keep myself stable and the wait for hammerheads began. Scalloped Hammerheads are a very shy species, easily spooked compared to other sharks. If you want them to come close, keep your dive group in a tight formation, calm your breathing and don’t make any sudden movements. 5 or so minutes passed and out of the murky cobalt waters the mysterious and elegant hammerheads appeared, swimming in a distinct formation - a scene I had only experienced in documentaries and photos. I hovered speechless, eyes wide open in awe at the magical event happening in front of me, a school of 50 Hammerheads, all covered in mating scars, and all ready for a well deserved clean. Before I could blink, 3 cruised over my head, and suddenly I was surrounded. The contrast between the yellow and red cleaning fish, the grey of the sharks and the blue water behind was beautiful and something only your memory can truly capture.
A fascinating recurring theme you will witness in Cocos Island are the amazing symbiotic relationships. Every dive is centred around cleaning stations situated at 25-30 meters depth. From here you will hide behind the volcanic rocks, staying as quiet as possible to encourage shy sharks to head to towards the rock formations. Here they get cleaned by fish like Wrasses, Barberfish and King Angelfish which congregate on rocky outcrops. The Hammerheads then slow down and give a very distinct signal by flashing their belly to the Cleaner Fish. The Cleaner Fish then know to emerge and begin grooming the shark. Suddenly a monochrome world of blues and greys bursts to life with colour. These small fish show absolutely no fear of the sharks when the predators are in ‘cleaning mode’. This truly is a symbiotic relationship where sharks get rid of parasites while the cleaner fish get a delicious meal. It’s something so special to witness.
Cocos Island is best known for the massive schools of Scalloped Hammerhead sharks that congregate around the seamounts, all swimming in the same direction (usually against the current). Witnessing hundreds of these powerful bodies moving gracefully and effortlessly in the expanse of the ocean is a transcendent experience that you really have to see to believe. Normally animals form groups with the goal of finding protection in numbers. However, Scalloped Hammerheads have very few natural predators. Therefore, safety in numbers is not the school’s main purpose. Adding another twist to this mystery, male Hammerheads are rarely seen schooling. Experts estimate that up to 90% of schooling Hammerheads at Cocos Island are female. Scientists have also pinpointed these schools to be a part of a mating ritual, with the larger dominant and more desirable females forming the heart of the school, with a few males swimming alongside trying to woo the largest female.
The mating process for sharks is aggressive and brutal, with the male shark biting the female in the process and on some occasion accidently killing the female. Mating scars can be seen all over the scalloped hammerheads body in Cocos Island and are a good tell-tale sign that you are looking at a female. Because of this aggressive biting behaviour from the males, females over time have evolved thicker skin to help protect themselves during this traumatic event.