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Evolution's Witness - How eyes evolved (Hardcover)
Loot Price: R3,139
Discovery Miles 31 390
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Evolution's Witness - How eyes evolved (Hardcover)
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With predation and carnivory as catalysts, the first known eye
appeared in a trilobite during the Cambrian explosion approximately
543 million years ago. This period was a crucible of evolution and
teemed with anatomic creativity although the journey to formed
vision actually began billions of years before that.
The Cambrian period, however, spawned nearly all morphologic forms
of the eye, followed by descent over hundreds of millions of years
providing an unimaginable variety of eyes with at least ten
different designs. Some eyes display spectacular creativity with
mirror, scanning or telephoto optics. Some of these ocular designs
are merely curiosities, while others offer the finest visual
potential packed into a small space, limited only by the laws of
diffraction or physiological optics.
For example, some spiders developed tiny, well-formed eyes with
scanning optics and three visual pigments; scallops have 40-100
eyes circling their mantle, each of which has mirror optics and
contains two separate retinae per eye; deep ocean fish have eyes
shaped like tubes containing yellow lenses to break camouflage; and
some birds have vision five times better than ours; but this is
only part of the story. Each animal alive today has an eye that
fits is niche perfectly demonstrating the intimacy of the
evolutionary process as no other organ could. The evolution of the
eye is one of the best examples of Darwinian principles.
Although few eyes fossilize in any significant manner, many details
of this evolution are known and understood. From initial
photoreception 3.75 billion years ago to early spatial recognition
in the first cupped eyespot in Euglena to fully formed camera style
eyes the size of beach balls in ichthyosaurs, animals have
processed light to compete and survive in their respective
niches.
It is evolution's greatest gift and its greatest triumph. This is
the story of the evolution of the eye.
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