Sharks

The top predator of the sea is a controversial yet intriguing title which is almost certainly deserved by none other than the shark, the most dangerous, vicious, mysterious, and cunning of prey animals. Sharks are known for having hundreds upon hundreds of teeth, swimming in the coldest and deepest waters, their killer blood sense and lust, and their astonishing diversity. 350 different types of sharks are currently identified which has them as one of the planet’s most abundant animal genres (Kimley & Ainley). In this essay, these most intriguing, beautiful, and elegant of hunters are explored from the safety of internet’s ocean of knowledge with the purposes adding to the existing appreciation, respect, and survival of the shark; the king of the ocean.

Introduction to Sharks

What is a shark? Sharks are many things however there are certain guidelines that can be used to discern them from fish and whales, creatures that may look like sharks but are not. Beginning with their skeleton, it is most interesting that sharks, the most violent and predatory of the ocean’s creatures have only cartilage, a rubbery sort of cell tissue, for skeletons. Other fish however may be composed of cartilage and bones (Enchanted Learning). Sharks are also unique in the ocean in that they may only go forward. Backward motion, something many fish are capable of, is thus unavailable to their physiology (Enchanted Learning). The Shark is also supported in their swimming buoyancy by a large oily liver whereas fish have a gas-filled swim bladder. Sharks are also known for their gill slits which are visible while fish typically have gills that are covered. The reproductive system of the shark is also different than fishes for they fertilize their eggs inside the female’s body while fish let their eggs be fertilized in water (Enchanted Learning).

The anatomy of a shark is designed for speed and hunting prey. At their front, they have the snout with a nostril inside that has extra sensitive receptors that allow them to sniff prey from many leagues away. A shark may smell a fish extract of one part out of 10 billion parts. Furthermore, researchers also find that sharks may sense and respond to one drop of blood within every million parts water (Edmond). Thus, the shark’s ability is akin to having the capacity to sniff out a teaspoon of something while swimming a large pool. Their astonishing talent is thanks to their nasal cavities which have two openings, each designated for inflow and outflow of water. The water once inside the nose passes through nasal sacs and through skin folds called olfactory lamelle, sensory organs with high numbers of sensory cells that are directly transmitted to the shark’s brain, an organ with up to two-thirds of its weight dedicated just to the housing of olfactory lobes (Edmond). Besides helping them to find prey, shark noses also are used for the detection of pheromones of potential mates as well thus making them well adapted to reproduction as well.

Within these stipulations, more than 350 different species of shark are known to scientists at this time however new types are being discovered daily. Most sharks swim in salt water environments in the open ocean and ; however,  there still are verities that may be found in fresh water conditions such as rivers and lakes (Live Science). Within the shark genome are many variations that give this family a huge presence in the ocean. Ironically, the largest of the shark family, the Basking and Whale Shark with bodies measuring up to 46 feet long, are some of the most harmless in the ocean with diets that are exclusively composed of tiny sea creatures such as plankton (Enchanted Learning).

The skin of the shark is also quite impressive. Their bodies have what are known as dermal denticles, minicule placoid scales that are actually very similar to teeth, something the sharks have no shortage of. Such a design allows them to literally cut through water resistance, a task that is further amplified by their being coated in enamel called vitro-dentrine adding another layer of smooth precession (Sharksider). It is this property of sharks that has made them a target among hunters as the skin may be flayed to make shagreen, a sandpaper and/or various leather goods. When swimming, it is common to see vortices and whirlpools quite often as the way the split the water is highly efficient and there spiracle. The dermal dentricles are also helpful as protection in the water as they grow in patterns based upon the need of the shark (Sharksider).

The body of the shark is composed of six main fins. The pectoral fin, the side fins near the gills, used to steer and lift in swimming (). The second set the dorsal fins, the sight most recognizable on the shark as the distinctive arch in the center of their backs and are used for stability. Pelvic fins are the sharks rear stabilizers and also may be used for holding by males in reproduction processes (). Anal fins rest behind these and are back up for the pelvic ones while caudal fins are the large rear ones with upper and lower components that propel the fish through the water with the majority of their thrust. The fins rest on a fusiform body, a shape that is rounded and tapered on either side thereby giving them minimal drag and maximum efficiency through the water ().  Shark coloration is typically that of the ocean. The colors are a combination of several shades of grey, blue, white, and navy-black.

Shark Types

The Whale Shark, Rhincodon Typus, while not a whale, as it is a member of the shark family, due to its size and form has the appearance of whale. Just like all sharks, whale sharks belong to the kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Chondrichtyes, meaning cartilaginous fish, subclass Elasmobranchii, composed of sharks and rays, order Orectoboformes (flat bodied sharks), family Rhincodontidae, with the genus/species giving the scientific name listed above (Enchanted Learning). The Whale Shark a flat head with a mouth of more than 4 feet wide are able process 1500 gallons of water each hour through them. The Shark is known to eat plankton, krill, fish, and squid with their mouths which are filled with 3,000 teeth that actually have very little use  and may weigh up 15 tons (Enchanted Learning). They breathe through their gill slits which are five pairs long while their mouths (Enchanted Learning). The whale shark, like many but not all sharks, are solitary creatures with groups of them only being seen very rarely. This shark may live to be as many as 150 years old, likely due to their nutrient rich diet of krill (Enchanted Learning).

The fastest shark in the waters is the Mako, a fish that reaches speeds of up to 60 miles an hour (Sharks-World). Makos typically, however, swim at 35 miles an hour, a speed usually maintained while migrating or hunting. Astoundingly, the Mako is known to leap as high as 30 feet in the air, something that has given them the propensity to even land in people’s boats from time to time. The Mako has a size range of 6 to 9 feet long yet some are known to reach 12 feet long. Unlike the Whale Shark, the Mako is known to act aggressively towards people and therefore should be avoided (Sharks-World). The Mako is hardly very picky about what it eats. Their main diet is swordfish, tuna, and herring however all options are available.

The most renowned shark is the Great White, the largest predator in the shark family since the prehistoric age. The Great White was the original of the Spielberg classic Jaws, a tale about a roaming blood thirsting shark that repeatedly wreaked havoc on a small town’s tourist destination shore (Kimley & Ainley 4). The Great White is one of the oldest of sharks with ancestors that date to the Eocene Epoch, a time of 56 million or so years ago (Long). The original ancestor of the Great White is the Carcharocles Megalodon, the super shark that was known to reach 45 feet and have teeth as big as a hand; for reference see the picture below. The Great White species of shark is a species found throughout temperate coastal waters where abundances of fish and marine animals gather such as the coast of Chile, the United States, Japan, Australia, and New Zealand (Long). The Great White is known to feed on fishes and other sharks with a diet that includes sea turtles, seals, sea lions, porpoises, dolphins and other whales. The prey is typically hunted with an ambush attack, something they will deliver on targets strong and/or sizable through a massive and almost certainly fatal bite. The attack is known to launch targets out of the water with their force and impact which can cause the prey to die instantly or soon thereafter as they are stalked by the Great White (Long). The White Shark is also known for acting as as well as they very indiscriminate in their feeding habits. People are thus commonly the targets of Great Whites however only about 7 percent of attacks are fatal (Long). The shark is mostly solitary yet may be found in pairs from time to time, a unique occurrence for the marine food chain’s top predator (Long). The only threat to them human beings and killer whales. Besides the Great White Shark, there are several dozen other fascinating sharks, the scope of which is outside the limits of this blog. Nonetheless, the distinctive character between the species listed so far suggests the diversity and intrigue found in the family group.

Shark Conservation

Thanks to their value as food and industry product in the creation of sandpaper and also hunting for big game and fear, the Sharks are under threat around the world. The World Conservation Union IUCN Red List gives 82 different sharks and rays, a fish species included in the shark family, as being presently endangered (Winter). Many of these are dying due to ocean contamination, the use of high-seas fish nets and/or the targeted practice of catching sharks just so that their fins can be harnessed for soup and folkloric remedies. Researchers believe that overfishing is a key challenge faced by today’s oceans with near 75 % of the fisheries reaching their limits. Some species may not even recover from these practices if they are not stopped soon (Winter).

Conclusion

Sharks are endangered and dangerous. They rest at the top of the ocean food chain yet they still are chained by human’s reckless oceanic activities. Nevertheless, sharks seem as killer and dangerous as ever. The world still needs sharks to instill the importance of respecting wild life, honoring nature’s designs, and seeing the beauty that is the movement and grace produced by this elegant and diverse killing machine.

Works Cited

Edmonds, Molly. Shark Senses: Smell. Animal.howstuffworks, 2016. Web. July 8, 2016. http://animals.howstuffworks.com/fish/sharks/shark-senses1.htm.

Enchanted Learning. All about Shark! Enchanted Learning, 2016. Web. July 8, 2016. http://www.enchantedlearning.com/subjects/sharks/allabout/

Kimley, Peter, & Ainley, David. Great White Sharks: The Biology of Carcharias. San Diego: Academic Press, 1998. Print.

Live Science. Sharks. Live Science, 2016. Web. July, 8, 2016. http://www.livescience.com/topics/sharks.

Long, Douglas. White Shark. Britannica, 2016. Web. July 6, 2016. https://www.britannica.com/animal/white-shark.

Sharks-world. Mako World. Shark-World.com, 2014. Web. July 8, 2016. http://www.sharks-world.com/mako_shark/.

Sharksider. Shark Anatomy: From the Outside In. Sharksider, 2016. July 8, 2016. http://www.sharksider.com/shark-anatomy/.

Williams, Amanda. World’s fastest shark. Daily Mail, 2013. Web. July 9, 2016. http://www.dailymail.co.uk/news/article-2370405/Worlds-fastest-shark-cousin-Great-White-caught-British-coast-time-42-years.html.

Winter, Steve. Endangered Sharks: Predator or Prey. Discovery, n.d. Web. July 9, 2016. http://www.discovery.com/tv-shows/shark-week/bios/endangered-sharks/