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Sharks are one of the most unique and interesting fish that dwell in every oceanic body on earth. They have evolved in such a peculiar way over 415 million years ago, which have made them stand out highly among any other type of predator fish out there. They are one of the few fish that if you see them, then you definitely know what they are without question. But aside from their physical appearance and massive size, what makes them so unique and at the top of their food chain?  I will be going over some facts about all species of sharks that are glossed over in many biology courses.

 

Electro-Sensing

Have you ever wondered why, when watching a documentary or Shark Week on television, that a shark has pinpoint accuracy in catching its prey? It is due to the fact that most cartilaginous fish have what appears to be a sixth sense; electro sensory. This is a type of sensory output that is inept to a shark’s survival, and can only be found in very few species of other fish in the ocean. What this does is that it allows the shark to see the heartbeat and electromagnetic pulses of organisms in the water. This electro sense mixed with a shark’s polarized vision (seeing a spectrum of colors such as silver, black and gray… think of the colorization of a sonogram), they can hunt down any prey they desire, especially if that prey is stressed or scared. Shoals of fish are not stupid, they can tell when a shark is coming and will swim away from those hunting areas when threatened. However, the ones that try to hide or get separated from their shoals are asking for a death sentence. The shark can lock onto this pulsation, and the sense becomes even stronger the faster the organism’s heart beats. So if you are a lone fish out in the middle of the ocean and a shark happens to come by, well good luck on survival, because it’s slim to none if you seem tasty enough.

 

Hunting

A shark’s hunting methods aren’t dependent on electromagnetic pulsations alone. As many of you probably know, sharks are attracted to the smell of blood… and urine. A pin drop of blood or urine can be detected by a mile away, and a shark will have a biological impulse to travel to the source that it is coming from. A shark will move its head side to side not only for sight, but also to allow the smell of blood or any other type of odor into each nostril. This helps them pick up the exact location of the source instead of swimming aimlessly around.

Once a shark finds a larger target of prey, such as a seal or squid, it will attack its target first and let it bleed out. Then, once it has been weakened and immobile from blood loss, the shark will come back and finish its prey off. Another unique trait that large sharks portray is that they will poke their heads out of the water to investigate their surroundings. Scientists are still baffled at the true reason for this, but it is most likely a curiosity trait since sharks are highly intelligent.

 

Woodridge, IL, USA --- Great White Shark Opening Mouth --- Image by © Denis Scott/Corbis

Survival

The larger species of sharks, such as bull sharks, threshers, or great whites, will swim over 1,000 miles a month; some reported to swim even more than this! To put that into perspective, that is nearly half of the distance from California to Hawaii. Not only that, but they can recycle their own body heat instead of relying on exothermic regulation to keep themselves warm. They are also counter-colored for camouflage. This means that the top of the shark will usually blend in with the ocean’s light wave reflection, and the underside of the shark will give off the sense of sunlight reflection to those who dwell underneath it.

Aside from these adept characteristics, a shark has a unique lateral line organ in their body that allows them to detect sound as well. This organ will take in sound waves and give off a ripple-like vibration which lets them “hear” the sound through their entire body. They are sensitive to noise in this way, and this will allow the shark to put its fight or flight response into effect. If needed, a shark can go 1 – 2 weeks without food. This is not unheard of, especially with over-fishing that humans have begun doing within the past couple decades, which is wiping out their food sources.

 

Do They Have Any Predators?

Yes. Aside from humans, which are predators towards everything it seems, sharks have 2 true predators. The first are other species of sharks. Sharks are not cannibalistic, but they will eat members of other genus’s if they are lacking food sources in their given hunting territories. The other predator to sharks was not known about up until less than a decade ago. This predator is the Orca.

 

Shark vs. Orca!

There was an observation done on a whale watching expedition off the coast of California where a couple of Orcas entered a group of Great White Sharks during their feeding frenzy. Now, Orcas are one of the smartest, if not THE smartest mammals on the planet (excluding humans again, and even then I wonder…). The pair of Orcas slowly swam on their backs toward the Great Whites, and rammed into one, causing it to flip on it’s back. When a shark is flipped on its back, they go into a trance-liked state called tonic immobility. They are unable to move, and being held in this position will eventually cause them to suffocate. The Orcas essentially drowned the shark, and continued devouring parts of the Great White before it died. The other sharks immediately gave up their feast and did not return to that area for quite some time, despite losing an entire month’s supply of fish. It seems like even an apex predator regards its life higher than that of food, especially when an even smarter creature invades its territory.

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*This picture is not of the stated Great White, but that of a Tiger Shark that an Orca is flipping over in a another scenario.

 

Quick Discrepancy When Swimming in the Ocean

Some of the above behaviors and characteristics should have stood out to you if you are a swimmer. If you happen to see a shark while in the ocean, try your best to control your fear or stress levels, especially if in a wet suit. A shark can mistake you for a seal or larger prey, and will not hesitate to bite you to find out. And obviously blood and urine will attract them, too, so please try to avoid urinating in the ocean while swimming, and try to avoid any sharp objects that may wound you. Although you have better chances of getting hit by lightning than being attacked by a shark (statistically true), it is always advised to be as safe as possible when you are in their home. I will be swimming with various sharks this September, so look forward to my upcoming article this year about my adventures with them!

 

 

Sources:

http://animaliaz-life.com/data_images/shark/shark1.jpg

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