Fish+Eye

=Dissection: Jordon's Fish Eye= This **[|Cow's Eye Dissection Guide]** is a useful starting point for dissecting an eye. Fish face some special problems when it comes to seeing under water - light rays bend or refract when passing through water; as water gets deeper, more light is absorbed; light is scattered by hitting particles of sand and silt in the water which creates a veil-like blinding effect for the fish. Fish eyes have adapted to see things in very low light levels. ||
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 * ==== **Follow Jordan's study of light as she dissects** ====

**a fish eye in search of a lens....**
||  || Making an incision in the **cornea**- the transparent covering over thefront of the eye. The cornea is pretty tough. It bends light, like the lens This cut allows the **aqueous humour** to drain out. || The **aqueous humour** is clear and watery at the front of the eye and jelly-like at the back of the eye. It's clear so that light can pass through it. It also helps to keep the shape of the cornea. You can see some fat and muscle around the eye. || Cutting through the **sclera** - the tough outer covering of the eyeball. || The sclera with the **iris**, the **vitreous humour**, the fat and the muscle removed. The **retina** is the dark colour at the back of the eye. || Removing the lens. The lens feels soft on the outside and hard in the middle. The fish eye lens is perfectly round like a pearl bead, not convex in shape like ours. || The job of the lens is to bend light to magnify the image of what the fish is looking at onto the retina at the back of the eye. The lens rests against the cornea for close-up vision and is pulled towards the back of the eye by special muscles for seeing things far away. || Jordan wanted to see if shining a light through the lens showed light rays bending in an way. Here, rays of sunlight focused through the lens making a pinpoint of light inside the lens. The edge of the lens looks fuzzy because of the soft structure of the outer layer. || Jordon experimented with the slide projector light to try to bend light rays through the lens. The light beam was too wide. A narrow beam from a laser pointer may have worked better. || Under the microscope..... || The clear structure of the lens inside is just visible below the soft outer layer. The special structure of the lens means that the fish eye can see things in very sharp focus. ||
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