Human Senses vs. Shark Senses, Fish Senses, andDolphin Senses Vision, Hearing, and Smell By Carrie Whitmore
HUMAN SENSES:VISION:Has a transparent lens thatfocuses light on the retina.The retina has over a hundredlight receptors that give us thepower to see. Our sharp colorvision comes from a small areacalled the blind spot because it The brain combines input of bothinterprets raw images our eyes see. eyes into one three-dimensionalControlled by one-third of the image.brain. Whenever the brain is Two defects in human vision areoverwhelmed with blindness and color blindness.emotion/thinking, vision can be In strong light, the iris contracts,impaired. which reduces the size of theThe human brain receives just aperture which admits light intoabout an unlimited amount of the eye. A protective obscureimages in a lifetime. It makes substance reduces the exposure ofdecisions on where to place its sensitive light cells.attention. We can’t always trustour eyes.
HEARING:The outer ear is shaped like a cup to The inner part of the human ear hasdirect sound towards the tympanic a vestibular system that is formed bymembrane. This transmits vibrations three semicircular canals, which areto the inner ear and goes through just about at right angles to eachmany small bones in the middle ear other and are responsible for thecalled malleus, incus, and stapes. sense of balance and spatialThe inner ear (cochlea) is a spiral- orientation.shaped chamber that is internally Finally, the inner ear also hascovered by fiber nerves that react chambers that are filled with ato vibrations and transmit impulses viscous fluid and small particlesto the brain from the auditory nerve. that contain calcium carbonate.Our brain combines the input of both Movement of the particles overears to figure out the direction and small hair cells in inner ear senddistance of sound. signals to the brain that areThe human ear can perceive interpreted as motion andfrequencies from 16 (very deep bass) acceleration.and 28,000 (a very high pitch) cyclesper second
SMELL:The nose is the organ that isresponsible for smell.The cavity is lined with mucousmembranes, which have receptorsthat are connected to theolfactory nerve.Smells consist of vapors ofvarious substances.The smell receptors interact withthe molecules of the smell vaporsand transmit the sensations to thebrain.The nose also has a structure Smell receptors of the nose arecalled the vomeronasal organ. The very sensitive to several types offunction of this organ has not been sensations, such as camphor, musk,determined yet, but it is thought to flower, mint, ether, acrid, orbe sensitive to pheromones which putrid.influence the reproductive cycle. The sense of smell can be temporarily lost when a human has a cold/is ill.
SHARK SENSES:VISION:In the majority of sharkspecies, their eyes are welldeveloped, large, and havecomplex structures.Some species are able to senselight and dark through a very thinsection of skin on the top of Focusing in sharks’ eyes is accomplished withtheir heads which leads straight the aid of the rectus muscles that pull theto the pineal gland of their brain. lenses closer to or further away from theMany sharks who live in shallow retina just as a camera lens focuses.waters can regulate the amount These muscles, along with the obliqueof light that enters their eyes by muscles control the direction the eye goes in.dilating or contracting their Due to the poorly lit environment wherepupils in the same manner humans some species live, they lack the ability to stopdo. light from entering their eyes.Focusing in sharks’ eyes is Most species posses excellent vision in lowaccomplished with the aid of the light conditions. The structure in their eyesrectus muscles that pull the that is responsible for this is called thelenses closer to or further away tapetum lucidum. Sharks share this abilityfrom the retina just as a camera with some nocturnal mammals/reptiles thatlens focuses require extreme sensitive vision to survive.
HEARING:It is unclear on whether sharkscan hear the same as humans ornot.The ears of a shark iscompletely internal. They’ areembedded within the front of theskull.Sharks’ ears are responsible forbalance and equilibrium. Theirinner ear has many ducts and sacswhich are known as endolymphaticducts.Around the membranouslabyrinth is more series of fluid Within this area is called thefilled canals (cartilaginous lagena that has been sound enlabyrinth) that are supplied discovered to receive waves inthrough the perilymphatic ducts. some fishes.This protects and supports the Their swaying back and forthmore fragile membranous registers on nearby sensory cellslabyrinth within. that send signals to the brainThe sacculus is a large inner resulting in sensations ofchamber into which the ducts imbalance that the shark thenlead. fixes and corrects.
SMELL:The idea that sharks are able tosmell a drop of blood from a mileaway in the ocean is highlyexaggerated.Sharks have a pair of nares(nostril like holes), which arelocated just under the edge ofthe snout.Each individual nare is divided bya nasal flap into two openings. Once sharks pick up a scentThrough these, water is trail, they swims up the throughchanneled into the incurrent the trail while moving their headsaperture and passed over the side to side. As their snout islamellae exits. bobbed from side to side throughDissolved molecules transported the scent trail, the shark is ablealong in the water bind to to figure out the direction fromreceptor cells that then sends a which the odor is coming from.signal to the brain (chemosensory Odor detection is not only usedfunction). in hunting, but sharks alsoSharks’ nares are completely produce pheromones to signalseparate from their mouth and their reproductive state tothroat and do not aid in potential mates. Smell may alsorespiration at all. be used in navigation.
FISH SENSES:VISION:Goldfish have superior visioncompared to humans.Humans can see red, green, and blueand can tell light from dark.Fish, however, can see those threecolors plus ultraviolet light that gives Fish who live in freshwater have no eye-lids thatthem polarized vision. It gives them the regulate the amount of light that enters their eyes.ability to resolve predators/prey through Many species of fish can see in color. This is whysurface of the water without trouble. fishing hooks are made in every single colorThis is why goldfish can recognize their imaginable. That way fish don’t get used to one colorowners and know their time of feeding. and stay away from the hook.Fish eyes are different from human Fishes eyes are located with one on each side of itseyes. Their lenses are perfectly round head. This allows fish to see on either side of the fishwhich allows them to see underwater. at the same time. However, the location of their eyes creates a blind spot that is located directly in front of the head.
HEARING:Fish have ears, but they are internaland don’t have openings.Sound travels three times fasterthrough water than the air. Thi s i s w peopl e ar e not supposed hyFish have a hearing range that is equal t o br eak pond i ce w t h a ham er dur i ng i mto AM radio. This is not bad, since w nt er . ihumans can hardly hear underwater. 160 deci bel s w l l dest r oy hum i anTheir difficult hearing system makes ear s, but i n t he dense w er m l ess at uchthem vulnerable to profound internal i s needed t o dest r oy t he audi t or y andand nerve damage when loud noises ner vous syst em of f i sh. soccur. Ponder s have r epor t ed i n t he past t hat l oud l ow frequencies t hat ar e r epeat ed, l i ke snow pl ow st r ess t hei r s f i sh out .
SMELL:Fish are given the ability to smellthrough their nostrils called nares. Theyare located on the snout of the fish.Odors that are in the water allow thefish to locate prey and predators.However, most fish do not rely on theirsense of smell to feed because what afish can smell at a specific time greatlydepends on the strength and directionof the water current.
DOLPHIN SENSESVISION:Dolphins have extremelygood vision.They have binocular vision,like a human does, but only toa certain degree.They can’t see colors reallywell. They have the vision of aseverely color-blind person.However, they don’t needmuch color vision, when theyspend 95% of their livesunderwater. Some of the dolphins behaviors that are associated with their vision show high uses of both sides of their brain, which is associated with intelligence.
HEARING:Blindfolded dolphins havebeen known to find smallobjects in their tanks usingecholocation.With their echolocation,dolphins can hear soundsfrom tiny objects that are asfar off as 120 yards away.Dolphins have two hearingorgans. The melon is a big off-center lump on theirforeheads that allows themto focus their echolocation Dolphins also have regularsounds. ears . Dolphins hearing is one of the best in the mammalian world.
SMELL:The smell sense of adolphin is not thatcomplex.Dolphins may not havea sense of smell at all.They don’t haveolfactory lobes in theirbrains and olfactorynerves are missing in alltoothed whales.This indicates thatdolphins may not have asense of smell at all. Itis still not known.
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