Chapter 2. Biological Eye  Designs

Chapter 3. Eye
 Design Illustrations
A. Plant light sensing
1. Grass, simple vines, 
and stems
2. Flowers
B. Lower animal eyes
1. Flatworms
2. Clams and Scallops 
3. Nautilus
4. Shrimp
5. Crab
6. Octopus and 
   giant squid
7. Spiders
8. Scorpions
8. Brittle Star 
C. Insect eyes 
1. Bees
2. Dragonflies
3. Butterflies
4. Flies
5. Ants
6. Moths
7. Beetles
8. Wasp
D. Fish eyes 
1. Shark
2. Flounder
3. Four-eyed fish 
E. Amphibian eyes
1. Frog
2. Salamander
F. Reptile eyes
1. Boa constrictor 
2. Rattle snake
3. Lizard
4. Turtle
5. Crocodile and 
    alligators
G. Bird eyes
1. Eagles
2. Hummingbirds
3. Owls
4. Ostrich
5. Cormorants
H. Mammal eyes
1. Whales
2. Elephants
3. Lions, tigers, and 
   other cats
4. Monkeys
5. Rats and mice
6. Bats
7. Tarsier
I. Human eyes
1. Iris
2. Lens
3. Retina

Chapter 4. Eye 
 Reproduction

Chapter 5. Optical 
 Systems Design 

Chapter 6. The Eye Designer

Related Links

Appendix A - Slide Show & Conference Speech by Curt Deckert

Appendix B - Conference Speech by Curt Deckert

Appendix C - Comments From Our Readers

Appendix D - Panicked Evolutionists: The Stephen Meyer Controversy
 

 
 
 
 
 
 
 
 

EYE DESIGN BOOK
Chapter 3
Section H
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3. EYE DESIGN ILLUSTRATIONS
H. Mammal eyes
      Mammals have camera-type eyes with a refractive lens to give well-corrected medium-to-high-resolution vision. Most mammals, including humans (see following section), have good focusing capability. This makes their eyes more versatile than more primitive eyes that are limited to fixed focus. High levels of preliminary parallel image processing are used with these eyes before signals go to the brain. Since most mammal brains are proportionally larger than those of most other creatures, they have the resources to process more information for recognition and protection. Eye optics transform light waves into visual images on the retina that provides much of the information received by the human brain. Since the eye is of extreme importance in the mammal functioning, since a large portion of the brain is used for visual processing. The relative size of eyes varies with families, size, and needs of the various mammals. The number of eyes, basic design, and construction of eyes is also quite consistent within most mammal species.
        Mammal eyes are almost spherical in shape and are located in orbital sockets in the skull. Eyelids covering the eyeballs appear to modify the shape. In general, sight occurs as light waves enter the eye through the cornea (the transparent layer at the front of the eye), pass through the pupil (the opening in the center of the iris, the colored portion of the eye), and then through a clear lens located  behind the iris. This lens focuses a light image onto the retina, which functions like the film in a film-camera or a CCD sensor in an electronic camera. Photoreceptor neurons in retinas, called rods and cones, then convert light energy into chemical and electrical impulses, which are carried to the brain via the optic nerves. At the visual cortex in the brain, electrical impulses are visualized as images. (Fig 3.44a adapted from 1999 Eye Poster from Anatomical Chart Co. Skokie, IL) (Fig 3.44b from p. 135, Iridology, Vol. 2, 1982, published by Bernard Jensen Enterprises, Escondido, CA 92027)

Figure 3.44a Diagram of  Human Eye.

Fig 3.44b Diagram of Human Eye as Typical Mammal Eye

      The requirement for processing of eye information in the mammal brain is expected to be greater than that required for most animal sensor systems. With simpler creatures, there may be only limited programmed responses to specific bits of visual information. As creatures become more complex, their reaction to visual information can require choosing from many different possible responses that may also be integrated with a learning process. 
     Hunting mammals have eyes forward, while hunted mammals have eyes on the side of their heads. The hunted animals need a wider field of view to see the hunters.
Some mammal eyes contain the equivalent of a curved mirror at the retina surface at the back of the eye where the eye reflects light back through sensors to its source. Mammals that have this type of eye include cats, whales, dolphins, horses, rabbits, antelopes, and hippos, etc. The color reflected is the primary color of the visual pigments in the photoreceptors. For example, white light reflects golden from cats' eyes, red from rabbits and hippos, and white from antelope. 
     Since mammals' eyes appear to be designed for unique roles, their eyes' controls and interfaces are uniquely programmed to process information for each vision system requirement. The following are some examples of mammal vision systems that illustrate the variation of mammal eyes.

1. Whales
      Whale eyes are about the size of a grapefruit. Because these multi-ton mammals can swim deep, their eyes need to be protected from high  pressure just as eyes of sharks and other similar fish are protected by hydraulic compensation. Whales are able to see well, both above and below the water using hydraulics to provide different focus positions in the eye. They can also see long distances in a variety of situations. They seem to navigate using solar or star patterns, when they are not able to see land. They have significant intelligence, as evidenced by how well they can be taught specific behaviors. (Figure 3.45 adapted from p. 94, Vision in the Animal World, Rubin Smythe, Macmillan Press, 1975) (Figure 3.46a from P. 294, Readers Digest, Exploring the Secrets of Nature, 1994), (Fig 3.46b from the National Resources Defense Council 40 W. 20th Street, New York, NY 10011, The Photo is by Frank Balthis. It is a newborn gray whale "spy hopping" in the San Ignacio Lagoon- the last untouched whale nursery in North America. Even small whales have some of the largest eyes of any living creature.)

Figure 3.45 Section of  Whale Eyes.

Figure 3.46a Picture of  Whale Eyes

Figure 3.46b Whale Eye

2. Elephants       The elephant needs to see long distances. Their range is large and they need to navigate over complex terrain. At the same time they need to see close up to care for their offspring. Since their eyes need protection during sandstorms or while being attacked by other animals, they have opaque and transparent coverings. These opaque eyelids are something like armor on a heavy tank, to protect their vision system. (By Bruce Chambers)

Figure 3.47 Elephant Eye

3. Lions, tigers, and other cats
      Like all cats, lions have retro-reflection characteristics that allow the eye to reflect light back to its source. Lions and tigers have large eyes, with long-distance vision, which they need for hunting. Like birds, such as hawks and eagles, they have good distance and night vision. Because of their excellent sight and tracking capabilities, they are among the best hunters in the world. Cat eye cross section is shown on fig 3.48. (Adapted from p77 Vision in the Animal World, R H Smythe, Macmillan Press, 1975)

Figure 3.48 Cat Eye Diagram  Figure 3.49b Baby Tigers

Figure 3.49a. Lion Eyes (By Bruce Chambers)

4.Monkeys       More than other mammals, such as  rabbits and pigs, monkeys' eyes have similarities with human eyes. In fact, all these eyes have tissue that is enough like human eyes for certain medical surgical research simulations. Monkeys do precise work and need to visualize complex patterns in limited light, so their eyes are somewhat similar to human eyes. A few species of monkeys also have excellent vision at night. Their night vision is probably needed for defense from their predators such as vipers, who also have night vision where they are able to sense heat or IR radiation at a distance. The following figures show some variation in monkeys eyes, but the big difference is in the eye size relative to the body size. (Pg. 83, Living Mammals of the World, Ivan T. Sanderson, Handover House, New York)

Figure 3.50 Larger Eyes relative  to the Monkey's body size

Figure 3.51 Smaller Eyes relative  to the Monkey's body size.

5. Rats and mice 
      Rat eyes contain a high index of refraction as its lens material. Their small camera-type eye requires unique lens materials equivalent to high index of refraction glasses. This allows a larger numerical aperture or smaller f/number lens to collect more light from a small eye. The light collecting capability of the rat's eye is quite efficient. This allows their small eyes to see in the dark better than many other mammals. Some mice eyes have been modified genetically to see better in the IR and UV regions.  For example, they can see at approximately 360nm (UV) light have a hard time seeing while humans below 400nm wavelength light. This comes from establishing UV cones in the eye with the proper pigments. In general this kind of UV light is harmful to human eyes, but since mice do not live long, their eye tissue is less important. The rat's eye is a good example of a small eye from which one can model small man-made optical systems.  (Pg. 57 The Illustrated Encyclopedia of the Animal Kingdom, 1970, Danbury Press) 

Figure 3.52 Mouse Eyes.

Figure 3.53 Bat Eyes.

6. Bats       In addition to eyesight, bats use acoustic echo sensing, which is similar to what we know as radar. Though they rely on visual clues for sight both day and night, when they operate in darkness they place higher priority on their echo location capability. Their unique image processing system is fast and efficient, which enables them to fly complex paths through small passageways at low light levels.  (P. 192 lower, Readers Digest, Exploring the Secrets of Nature, 1994)

7. Tarsier        The volume and weight of eyes, as a percent of total weight or volume for all mammals is somewhat consistent in comparison to more significant variations in the eye size of insects. An exception is the tarsier, a small mammal of Southeast Asia. It has the largest eyes in proportion to its body weight of any mammal. Even when comparing eyes as a percent of total body volume, its eyes are significantly different. Many times larger proportionally than human eyes, the relatively large eyes of the tarsier enable them to see better at night.

Figure 3.54 Tarsier Eyes-with large  iris opening (Pg. 46, Living Mammals  of the World, Ivan T. Sanderson, Handover House, New York)

Figure 3.55 Tarsier Eyes-with small iris opening (Pg. 46, Living Mammals  of the World, Ivan T. Sanderson,  Handover House, New York)