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Conventional Eye Evolution
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Evolution of the Eye https://www.youtube.com/watch?v=7jEhzAn1hDc
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Evolution of the Eye
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Evolution of the Eye
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Evolution of the Eye
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Convergent Evolution In vertebrates, 1 represents the retina and 2 is the nerve fibers, including the optic nerve (3), whereas in the octopus eye, 1 and 2 represent the nerve fibers and retina respectively. 4 represents the blind spot, which is notably absent from the octopus eye. Vertebrate and Cephalopod eyes
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Learning from Echinoderms!
A Road Less Travelled By
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Echinoderm Diversity
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Starfish Crinoid Brittle Star Sea Urchin Sea Cucumber
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The brittle star Complete illustration of an ophiuroid, Ophiocoma scolopendrina (Ophiuroidea, Echinodermata). It consists of a central disc and five arms. All the arms are completely identical, forming a radially symmetric shape.
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The brittle star Complete illustration of an ophiuroid, Ophiocoma scolopendrina (Ophiuroidea, Echinodermata). It consists of a central disc and five arms. All the arms are completely identical, forming a radially symmetric shape.
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Brittle Star Complete illustration of an ophiuroid, Ophiocoma scolopendrina (Ophiuroidea, Echinodermata). It consists of a central disc and five arms. All the arms are completely identical, forming a radially symmetric shape. Wataru Watanabe et al. J. R. Soc. Interface 2012;9:
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Brittle Star http://cronodon.com/BioTech/Ophiuroids.html
Complete illustration of an ophiuroid, Ophiocoma scolopendrina (Ophiuroidea, Echinodermata). It consists of a central disc and five arms. All the arms are completely identical, forming a radially symmetric shape. Wataru Watanabe et al. J. R. Soc. Interface 2012;9:
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Radial Nervous System: Look, Ma, No Brain!
Schematic of nervous system of an ophiuroid. ‘Radial nerves’ innervate the arm movements, and they are connected to each other through a ‘circumoral nerve ring’ in the central disc. Wataru Watanabe et al. J. R. Soc. Interface 2012;9:
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Brittle Star Locomotion
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Brittle Star Locomotion
Wataru Watanabe1, Takeshi Kano1, Shota Suzuki1 and Akio Ishiguro
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Brittle Star Behavior Seek refuge in shadows, caves
Detect them from several centimeters away, but how?
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Night and Day Lightsensitive brittlestar species Ophiocoma wendtii changes color markedly from day (left) to night (right). Ophiuroid eye video! feat. Dr. Gordon Hendler
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Armor and Eye in One Lightsensitive brittlestar species Ophiocoma wendtii changes color markedly from day (left) to night (right).
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Brittle Stars Are All Eyes
Electron micrographs of calcite skeleton reveals thousands of lenses Each 40 – 50 micrometers across Each focusing on spot 10 micrometers deep => nervous system "Once again we find that nature foreshadowed our technical developments," says Roy Sambles of the University of Exeter in the United Kingdom
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Brittle star eyes (Left) SEM of the cross section of an individual lens in O. wendtii. (Below)Scanning electron micrograph (SEM) of a brittlestar lens design
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Brittle star eyes Lens: composed of tiny calcite crystals. Calculated lens: what a manufactured lens would look like, performing the same function. Nerve bundles probably pick up light signal.
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Brittle Star Eyes: Biological Shades
Schematics of filtering and diaphragm action of chromatophores Upper: night: shades of grey Lower: day: reddish brown pigment-filled chromatophore cell; R – receptor; P – pore; L – lens
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Biomimic of Brittlestar eyes
Transmission tunability through a lens array using controlled transport of light- absorbing liquid in the channels between lenses. Images formed near the lenes focal point c)without and d) with light absorbing liquid
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The cover of the journal Science features an up-close look at an artificial compound eye. The honeycomb structure is an array of mini-lenses, each of which is hooked up to a device for transmitting the incoming light signal to a central processor.
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Eye Evolution “slides” click
Animals have come up with a wide variety of solutions to capturing light But: Mantis shrimp's super colour vision debunked
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What can this fish tell us?
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the first vertebrate known to have developed mirrors to focus light into its eyes.
it technically has two eyes, each of which is split into two connected parts
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Spookfish give us an eyeful
(A–C) Flash photographs of a recently captured spookfish in both dorsal (A and B) and ventral (C) view. Note the yellow-orange eyeshine in the main tubular eyes in the dorsal view and the eyeshine from the diverticulum when viewed ventrally. The black structures lateral of the main eyes in the dorsal view are the upper surfaces of the diverticula. (D) Ventral view of both eyes removed from the head, showing the silvery argentea on the base of the main eye. The ventral edge of a “mirror” within the diverticulum (arrow) is clearly visible through a transparent ventral “cornea.” A Novel Vertebrate Eye Using Both Refractive and Reflective Optics Hans-Joachim Wagner , Ron H. Douglas , Tamara M. Frank , Nicholas W. Roberts , Julian C. Partridge Current Biology, Volume 19, Issue 2, 2009,
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Spookfish Eyes: Here’s Looking at you!
above Mirror eye - light from below Retina Mirror Tubular eye – light from above Lens The eyes of the six-eyed spookfish direct additional light to the principal eyes for improved deep-sea vision via a third pair of accessory 'eyes’, not shown. "The six-eyed spookfish (Bathylychnops exilis) has an optical system that is unique in the animal kingdom. Unknown to scientists until as recently as 1958, and dwelling at depths of feet ( m), this slender pike-like fish has paired, downward-pointing, spherical organs housed within the lower half of its large eyes. These were once believed to be light-producing organs - bioluminescence is a common phenomenon among deep-sea fishes. Closer examination, however, exposed their much more extraordinary, true identity. In reality, these organs, now referred to as secondary globes, are accessory eyes. Each of these globes possesses its own lens and retina and probably serves to increase the spookfish's sensitivity to light (photosensitivity) within its dimly lit undersea realm. "But this is not the only anomaly of its optical system. Scientists subsequently unfurled a further surprise associated with the fish's accessory eyes. Behind them is a third set of 'eyes,' even tinier than the secondary globes, but less sophisticated. These 'eyes' lack retinae. Instead, they serve merely to direct incoming light into the spookfish's principal pair of eyes, thereby enhancing these latter organs' powers of vision." (Shuker 2001:13) below
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So, where’s the Biomimicry?
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