Evolution

Why are Sharks so Evolved



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"Why are Sharks so Evolved"
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It would be logical to argue that sharks have actually evolved to the point where they posses 7  distinct senses. Which makes one think about how perfect of an organism sharks must be. Sharks posses very unique sensory structures that would only be effective by use in their home medium of water.  The reason for their development is in fact primarily based in their aquatic environment. In hunting, sharks are predatory and often have multiple tough challenges to overcome. While they may possess sharp teeth or a gaping jaw to inhale their prey, the actual task of locating, tracking and catching their prey could prove difficult. Fortunately for them, they have developed distinct and original sensory systems to seek out their prey, some of which we as humans do not and will not ever posess.

Smell

There is a reason why sharks have been observed to be the perfect predator of the sea and in many cases; species of sharks have not needed to evolve any new traits for millions of years.  They have keen olfactory (smell) reception due to their super sensitive chemo receptors.  Their “nose” is located in the short duct between the nasal openings.  Many species can detect up to one part per million of blood within the water. To put it metaphorically, if a million pebbles were laid out and only one was sprayed with perfume, the shark could pinpoint it.

Water Pressure

Sharks contain what is known as the lateral line which is common to most evolved fish.  The line contains specialized cells with are used to detect slight changes in pressure and movement within the water using specialized hairs encased in the line or tube along their body. The tube is filled with water, but is naturally protected from a water current due to movement.  The hair cells inside the lateral line or tube are so sensitive, that they can detect the movement of prey just through the displacement of the water. 

Electric Reception

As if this motion detection using simply pressure was not sufficient, sharks also possess specialized electric location cells.  Sharks are specialized to be sensitive to the electrical signal given off by the muscles of their prey.  The hammerhead shark is especially sensitive and this sensory system actually accounts for its unique head shape.  The head is riddled with electric sensing cells called ampullae of Lorenzini. They have mucus that is actually electrically conductive and as it covers the electric receptor cells. The very minor electrical impulses of a prey fish in motion is enough to trip these receptors allow the shark to track its prey.

There are two types of reception used.  Passive electro location is used when constant active reception is used to locate prey by detecting environmental electrical fields.  Active electro location is used when the predator actually generates its own electric field and uses sensory input form this field to locate prey.  The fields can come in the form of pulses, much a like a Doppler radar, or in the form a constant flow of electrical energy or “hum”.

Evolved Anatomy

Goblin sharks in particular not only use these electro receptors but they also possess a very distinct and advantageous jaw.  The jaw has the ability to move both upper and lower halves like a bear trap rather than just the lower as in most sharks.  This provides an incredibly fast and powerful bite upon its prey.  The goblin shark also has the ability to extend its jaw full out ward from its head. A hinge allows the jaws to protrude in an eerie fashion outward.   When prey is detected by the various receptors. The jaw protrudes and bites im a surprise attack styling.

'The additional senses and evolutionary predatory anatomy make sharks the top of the totem pole in the aquatic food chain.  We are lucky as humans that there is no such land predator.

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