Free Powerpoint Presentations

Compare Visual System of Fish to Human
Page
2

DOWNLOAD

WATCH ALL SLIDES

In fishes eyes the rods are physically retractable. When light levels are high the rods are retracted into the back of the retina and covered with a black melanin layer. When light levels fall and the cone sensitivity degrades the rods move upwards to lie alongside the cones to provide gray scale vision.

Slide 6

The Reflective Eye

The Reflective Eye

Some fishes have a Tapetum lucidum, a reflective eye, similar to nocturnal animals. They have a reflective system on the retina to reflect light which has already passed the rods, back for a second chance at detection. The sight is very slightly blurred but it is very sensitive.

The fact that these species have a reflective eye creates problems when fish are removed from photon limited water conditions and/or flashed with cameras. They can be heavily light shocked and become disoriented which does not help their survival on release in crocodile infested waterways.

Slide 7

The Eye

The Eye

Photoreceptor properties

Dynamic retina

Slide 8

05-03

05-03

W. W. Norton

Human Photoreceptors

Slide 9

Kusmic et al. (1992)

Kusmic et al. (1992)

Retinal rods contain a visual pigment with max at 512 nm.

Adult trout the retinal cone system consists of single and double cones with pigments having peaks at

453 nm (single cones and one member of double cones),

530 nm (single cones and one member of double cones)

598 nm (one member of double cones)

Slide 10

4 cpd

4 cpd

Slide 11

The Eye

Slide 12

High Frequencies

High Frequencies

Slide 13

Medium Frequencies

Medium Frequencies

Slide 14

Low Frequencies

Low Frequencies

Slide 15

Species

Species

Slide 16

Wheeler, 1981

Wheeler, 1981

Teleosts

Animal's ability to perceive stimulus a function of temperature and season.

Specialized features

Reflective tapetum (part of pigmented layer of the eye, which has an iridescent luster and helps to make the eye visible in the dark)

Area and temperature dependent distribution of visual pigments

Area-specific distribution of photoreceptor types

D

Go to page:
 1  2  3  4 

Contents

Last added presentations

2010-2019 powerpoint presentations