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Sharks: The Oceans Greatest Mystery – Part 1

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The word ‘Shark’ can instill a mixture of emotions in the human psyche, they are referenced in human cultures throughout the world, and stories of Sharks were commonplace on the decks of Ships for millennia. They have been represented in myth as both powerful guardians and vicious villains, in the 16th Century sailors and whalers of the time referred to sharks as “Sea Dogs” and are referenced in the Bible as being manifestations of the devil, even the word Shark is translated from the German word Schurke which means “scoundrel”. However, in French Polynesian and Hawaiian cultures they are revered as powerful gods and guardians who watch over fisherman and their families.

With such huge differences in how we view them, it is no wonder how inaccurately Sharks are portrayed in modern day media, therefore throughout this three-part blog series I am hoping to help you to better understand what a Shark truly is, and I will be covering subjects such as: What is a Shark? What we know and what we do not know about them, what is threatening them, and how we can be better ambassadors to Sharks worldwide.

What is a Shark?

In this first blog I want to give you a better idea as to what a Shark is and how they have become our oceans top predator. What a lot of people think of when they first imagine a shark is that they have sharp teeth and tend to always have ominous music following wherever they go, however there is much more to these animals than their teeth. Recent discoveries have shown that the Greenland Shark can live to be up to 500 years old, and the Bonnethead Shark is the first known Omnivorous Shark where up to 60% of its diet consists of Sea Grass. These are just two of many recent exciting discoveries, and scientists predict that we are about to enter the golden age of Shark discovery!

Sharks are a part of the fish family, although they are part of a distinct group that separated from Bony fish around 306 million years ago. Early relatives of Sharks have existed on our planet for as far back as 400 Million Years, they have been around longer than Humans, Dinosaurs and even trees. Throughout time sharks have taken many shapes, sizes and forms, but all have one thing in common, the makeup of their skeleton. The skeletons of Sharks and their relatives (Rays & Ratfish) all have a skeleton made of cartilage which is the same substance as your ears and nose, this allows them more flexibility in their movements and gives them an edge over their prey by allowing faster turns and giving them access to tight spaces and crevices.

Sharks, like other fish, also have Hyostylic jaws which means that the upper jaw isn’t connected to the skull, this allows more movement and flexibility in their strike when hunting. Sharks are also accompanied by two additional senses compared to humans, they have a lateral line which allows them to detect movements over 100 metres away and can detect frequencies as low as 25 Hertz, they also have their Electroreceptors which can pick up minute amounts of electricity given off by their prey’s muscles, such as the heart, and Sharks use this to help find prey buried in the sand, or to help pick off individual fish in the dark.

When it comes to sharks and what they eat, the best way to sum it up would be to imagine that for every animal in our Earth’s Oceans, there will be Shark that is designed and capable of eating it. This means that Sharks have become an incredibly diverse group, and as it stands there are over 500 species of Sharks, which range from the 14-Metre-long Whale Shark, all the way down to the Dwarf Lantern Shark, which is the smallest known shark species and it can fit into the palm of your hand. In between these we have large species such as White Sharks that breach from the water whilst trying to capture Seals, and smaller species such as the Dark Shy Shark that curls into a doughnut and covers its eyes with its tail when it is startled.

Another interesting point about Sharks is that they have come up with many different ways of tackling prey and have specially adapted teeth that match their diet, Sharks that have very needle like teeth such as the Sand Tiger Shark or Mako feed mainly on fish or other slippery prey, if the teeth are large and triangular like those of the White Shark or Tiger, then they prey on larger animals such as marine mammals, and if the teeth are flat like that of Nurse Sharks or Port Jacksons it generally means they feed on hard shelled and tough animals such as Shellfish and Snails. Teeth are not the only adaptation Sharks have evolved to use to their benefit, their differences in body shape or design can also indicate to us the hunting techniques they use, a good example of this would be the Hammerhead Sharks, which use their unique shaped heads to pin their prey against the seabed.

Sharks are often thought of as cold blooded, however this isn’t true for all species, some Sharks, such as White Sharks and Makos, are able to warm their bodies a few degrees warmer than the water, Scientists have predicted this is caused by the movement of the muscles generating heat. This heat has most notably been found around the eyes and brain; this may be an adaptation to help their eyes and brain react faster whilst tracking prey during high-speed chases.

Are Sharks Maneaters?

Sharks have been negatively portrayed in the media for as long as we’ve been swimming in our oceans and it is only recently that we’re starting to discover the positive impacts of Sharks and just how important they are to our Oceans and our Planet. Sharks have been represented as maneaters, but in fact sharks are only accountable for an exceedingly small number of incidents relating to a Shark bite, Sharks are in fact more likely to avoid human interaction and encounters with wild Sharks are a lot rarer than you would once think. To put things into perspective you’re more likely to be killed by a falling coconut or vending machine than you are to be bitten by a shark.

Even the age-old myth that Sharks are attracted to Human Blood has been proven to be false, after it was recorded that Human Blood and other bodily fluids have no effect on a shark’s behaviour or heart rhythm, this is due to our blood having a higher iron content than that of their regular prey. Even the way we look and move doesn’t resemble the prey of Shark. But the question people always ask is why do Sharks bite if they do not view us a food item? This is due to Sharks curious nature, Sharks have to be curious to discover what is and isn’t edible and, in our case, when Sharks bite it tends to be very quick lasting mere seconds before it lets go of us and swims away this is due to the animal realising that we aren’t a part of its regular diet and releases us.

If you want proof that Sharks aren’t what media would have you believe just look for any image with a Sharks and Diver, Snorkeler, or Swimmer if the media or movies have any ounce of truth then these people would’ve been killed a long time ago but these images solidify how wrong we’ve been looking at Sharks throughout the years.

So that’s it, an introduction to the Oceans Greatest Mystery, I hope that you have a greater understanding into what a Shark actually is and to how fascinating this amazing group of animals are but stay tuned for the next entry in this series where we dive deeper into the strange world of Sharks and discuss what we do and don’t know about them.


Follow Donovan on Instagram at www.instagram.com/donovans_reefs

Donovan is a Divemaster who currently works as a Shark Diver at Blue Planet Aquarium based in Ellesmere Port. Donovan’s passion lies with Elasmobranch’s (Sharks & Rays) and this passion has led him to work in South Africa with White Sharks for a short period. He also believes that education through exposure is the best way to re-educate people about Sharks. Follow Donovan at www.instagram.com/donovans_reefs

Marine Life & Conservation

The BiG Scuba Podcast… with Andy Forster of Dive Project Cornwall

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Gemma and Ian chat to Andy Forster.  Andy is the Project Director at Dive Project Cornwall.  He tells us about his own passion for diving as well as how Dive Project Cornwall is going to educate and inspire many youngsters over the coming year.

Have a listen here:

Find out more at www.diveprojectcornwall.co.uk


Find more podcast episodes and information at the new www.thebigscuba.com  website and on most social platforms @thebigscuba 

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Marine Life & Conservation

Coral Spawning Predictions for Curacao and the Southern Caribbean

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The Caribbean Research and Management of Biodiversity (CARMABI) has released its 2022 annual coral spawning prediction calendar for Curacao and the south Caribbean.  This calendar plays a central role in studying the reproductive biology of Caribbean corals and guiding coral restoration efforts for the southern Dutch Caribbean islands.

Based on these predictions, researchers are able to harvest coral gametes that are reared to larvae that can be used to cultivate future coral colonies.

Coral spawning is a miraculous event where entire coral colonies, prompted by the lunar cycle, sunset time and water temperature, release gametes (eggs and sperm) simultaneously. Gametes of one species fertilize another to become fertilized embryos that settle on the ocean floor after days to weeks.

CLICK HERE FOR MORE DETAILS!

As divers, being able to witness a spawning event is a unique opportunity to enjoy the breathtaking scene as the entire reef becomes engulfed in a blizzard of future corals.

Each year, the Caribbean Research and Management of Biodiversity (CARMABI) releases a calendar to predict when each species of coral is expected to spawn. During these events, researchers from CARMABI, in collaboration with Reef Renewal Bonaire and Reef Renewal Curaçao, also collect gametes to be used to grow new corals in a laboratory setting.

Photo credit = CARMABI

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