Vision of Fish

By Andrew McDonaldwww.yahoo.com

Outline

• Introduction• Challenges of water• Absorption of light• Refraction of light• Anatomy of eye• Light regulation

Jim Lavarakas

IntroductionOptics : the collection of light and formation of an

image by the lens

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Accommodation : focusing of images on the retina

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Eyes of Fish• Much like

human eyes• But no eye lids• Many sizes and

colors

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www.ebiomedia.com

Anatomy of Eye• Sclera• Cornea• Lens• Iris• Retina• Optic nerve

Powerful Eyes• Spherical lens

• High refractive power

• High quality

• Receptors: cones and rods

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www.appstate.edu

Problems With Seeing Problems With Seeing Under WaterUnder Water

• Suspended particles

• Light absorption

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•Light refraction

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Suspended Particles

• Sediments• Microorganisms• Plant growth• Fast-moving

waterwww.hurleywi.com/ what_to_do/default.asp

Light Absorption

• The dimming of light as it passes through water

• Red wavelengths absorbed rapidly

• Blue wavelengths absorbed slowly

• Deep ocean is blue

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www.rainbows.com

Light Refraction• Cone of Vision

• Water bends 48.6 degrees

• Freshwater pools

• Snell’s window

Snell’s window

Light Regulation

• To limit light• Iris contraction• Smaller eyes• Migration of visual

cells• Cornea filter

pigments• Swim away from

light

Light Regulation• For more light:

• Mirrors in back of eye

• Larger eyes• Swim toward light

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Walleye

Conclusion

• Some similarities w/ humans

• Different environments

• More obstacles• More diverse• Altered behaviors