TYPE OF EYES BY : NUR AIN AMANI BINTI ABDUL MUBIN

THE EYES  The organ of vision  Detect light and convert it into electro-chemical impulses in neuron  Eyes are divided into compound eyes and non- compound eyes  4 types of eyes : flat-sheet eyes, cup-shaped eyes, vesicular eyes and convex eyes

FLAT-SHEET EYES  Provide some sense of light direction and intensity  Most often seen in larval forms or as accessory eyes in adults  Can also be found in group of invertebrates (e.g, larvae)

FLAT-SHEET EYES  Valuable to animal either sessile or moving passively  Singular light sense cells on body can differentiate between light and dark  In larvae, may be benefit from a shadow reflex to protect itself against predator  Can also detects outline of nearby objects  Track movement of prey

CUP-SHAPED EYES  Detect intensity and direction of light  Retinal sheet is folded to form a narrow aperture  Developed as the pit deepened into a cup, then a chamber  Form image but in poor resolution

CUP-SHAPED EYES  Can be found in Nautilus  Achieve true imaging by reducing the size of aperture  Allow Nautilus for fine directional sensing  Also helps Nautilus to achieve neutral buoyancy  Use to track prey and predator

VESICULAR EYES  Lens in the aperture improves clarity and intensity  Lens refracts light and focuses it onto a single point of retina  Form image in high resolution  Present in most vertebrates (e.g human)

VESICULAR EYES  In predatory gastropods, they now could better recognize and follow prey  Helps to form better image compare to cup-shaped eyes which give poor resolution

CONVEX EYES  Photoreceptors radiate outward  Retina is convex  Present in annelids, mollusks and arthropods  Gather more light than a flat or concave one

CONVEX EYES  The photoreceptor cells collect light stimuli and send signal to the brain through afferent neuron  Help animal to survive with a better image

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