A Shark’s Role & Adaptions
For years, fictional films have been made that paints sharks in a bad light. The truth is you are statistically more likely to be fatally injured by a sand hole than you are to be attacked by a shark in the US. Sharks aren’t the blood-thirsty killers horror films make them out to be; instead, they will choose to scavenge on a corpse if they had the choice.
They do not hunt for sport; they hunt for food to survive like any predator.
Before we learn more about this incredible animal, I worked with a shark behaviourist to answer some fascinating questions for you:
How can you tell a shark’s emotions by its behaviour and how can you tell if it’s a relaxed shark?
“You can typically tell a shark is relaxed by how fast it swims and if it shows erratic movements - a relaxed shark cruise fairly slow around, just jolting slightly when getting food. When a shark is unhappy, it starts swimming faster and exhibits fast movements such as bending its back and gaping.”
How can you tell the gender of a shark?
“Males are usually smaller and u can tell by looking on the underside of the shark for claspers (the external sexual organs of male sharks)!”
All questions were answered by shark behaviourist Cicely Nagel, her Instagram username is @cic_ocean.
Here are some questions that I answer myself that I believe are either extremely important for people to know or are simply fascinating. This blog’s mission is to help stop the misunderstanding of sharks, which is leading to their extinction due to the hatred humans have towards them.
Why do we need sharks for oxygen?
Using the method of using phytoplankton, the sharks help the ocean create 70% of the Earth’s oxygen, which only makes sense as the ocean covers 70% of the planet.
Phytoplankton is microscopic single-celled plants that aren’t visible to the naked eye and though they are small, they are extremely great in numbers. Trees, though they are larger, they are more important and more efficient in locking away carbon than they are for producing oxygen. Phytoplankton are strong winners when it comes to oxygen production, making it that much more precious to protect. When sharks produce waste, the phytoplankton feed on the waste and use it as fuel to create 70% of the planet’s oxygen.
How do sharks breathe?
There are 3 different techniques sharks have adapted to breathe. The most well-known technique is called “ramming:” when a shark has to continuously swim to pull water over its gills to breathe.
Another technique is known as “suctioning” which is the same way that goldfish use to breathe; they continuously use their large cheek muscles to open and close their mouths which suction the water in their mouth and through their gills.
The final technique is one that very few people know of: “buccal pumping.” These specialised sharks have evolved a secondary respiratory organ that allows bottom-dwelling sharks to breathe and avoid breathing sand. This is because these sharks are close to the sandy ocean floor. This specialised organ is known as the spiracles which act almost like nostrils on the top of their head.
But how do gills work in comparison to our lungs?
Our lungs have a layer of red blood cells that absorb oxygen and release carbon dioxide as we inhale, the gills of sharks work similarly. From the inside of the shark, the gills have a layer of red blood cells of their own that will also swap carbon dioxide for oxygen when water passes them.
Blood-thirsty or opportunists?
Although they hunt live prey, sharks that are given the “blood-thirsty” title such as the great white shark and tiger shark have been recorded scavenging on carcasses of whales. And despite a shark's shocking reputation, its role in our natural systems is of the utmost importance.
Sharks are also known as ‘vultures of the sea’ as they are the natural bin men of the ocean. They eat dead animals such as whales, preventing the outbreak of diseases that would interrupt the balance of populations and systems of the ocean and the rest of the planet as the health of the ocean also affects the health of the land. Their all-powerful immune systems also prevent the sharks from becoming sick.
In other words, when sharks go extinct, so will the rest of the ocean. Sharks were on Earth before dinosaurs due to their so-important role.
Why is the saltwater bull shark often seen in freshwater rivers?
Nope, bull sharks do not do this in search of food, they especially do not do this to ‘come for humans.’ They actually do this to birth their young in safer waters away from the deep ocean where the shark pups will be safe from the majority of predators. To survive in freshwater, bull sharks have adapted unique special glands which store the ocean's saltwater for their body when they swim in freshwater rivers. If they lose that precious sea salt, their cells could expand and rupture, leading to death. The glands near the tail retain the sea salt, and the shark’s kidneys recycle the sea salt when the shark is in freshwater. This process is known as ‘osmoregulation.’
How do sharks stay buoyant?
Unlike most fish such as the beloved goldfish, sharks do not use a swim bladder with a gas inside but instead, they use specialised oils within their liver as well as their fins to stay buoyant because if they stop swimming, they will sink. Therefore, despite the oils in their liver to help keep them buoyant, their buoyancy relies mostly on the shark itself and its movements.
What is a shark’s skeleton made of?
Not bone like us! A shark’s skeleton is made from cartilage which makes them part of the Chondrichthyes class instead of the Osteichthyes class of bony fish. The only part of a shark's skeleton that can be preserved is the jaw as it’s the only part that is made from bone.
Why does a hammerhead shark have the iconic head shape it does?
Why do sharks have that bizarre head shape that gives them their famous name the 'hammerhead' shark?
Well... Have you ever used a metal detector? You see, these usual sharks may not detect metal, but they do detect the electrical impulses made by other animals such as stingrays that hide by burying themselves under the sand. Although all sharks have this incredible 6th sense known as the ampullae of Lorenzini. They have this sense by using the black pores on their faces and due to the adapted head shape of the hammerhead shark, not only do they have 360° vision, but they also have an immense 3,000 of these black pores to be able to sense these electrical properties. They glide around the bottom of the ocean waiting to sense any sort of stingray until they take their ferocious strike.
Have a question about sharks? Let me know!
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