rod-cells

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Oilbird

The oilbird (Steatornis caripensis), locally known as the guácharo, is a bird species found in the northern areas of South America including the island of Trinidad. It is the only species in the genus Steatornis and the family Steatornithidae. Nesting in colonies in caves, oilbirds are nocturnal feeders on the fruits of the oil palm and tropical laurels. They are the only nocturnal flying fruit-eating birds in the world. They forage at night, with specially adapted eyesight. However they navigate by echolocation in the same way as bats, and are one of the few kinds of birds known to do so.

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In the retina, there are two different types of light-detecting cells: rods and cones. The rods are used for seeing in low-light conditions, and there’s only one kind of those. The cones are a different story. There are three kinds of cone cells that roughly correspond to the colors red, green and blue.

From the TED-Ed Lesson How we see color - Colm Kelleher

Animation by TED-Ed

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I had this all written out in another post and was an idiot and deleted the post, so HERE WE GO AGAIN.

Basically, while looking up hedgie things, I’ve found a couple of conflicting sources saying that hedgehogs have dichromatic vision (two different types of cells to pick up colour/ cones), whereas others say they only have rods (the cells that pick up black/white). However, the sources that say they only have rods also say that some of their rods have cones in the nuclei..? I have no idea how that works, but basically, it would let them see some VERY limited colour, but only in good lighting.

Furthermore, being nocturnal, hedgehogs rely more on their smell than sight, and hedgehogs suffering from eye trauma or blindness live fairly normally.

Now, fool that I am, I gathered, maybe this is why Sonic and Shadow could look so similar. No. Their colour schemes are very different and Sonic is really fucking blue. Like, take any image of this fucker ever he is VERY BLUE.
Even if you take out most of the colour, the fact that he is really fucking blue means that he still looks very clearly different. 

However, colour differences aside, if the lighting is bad enough to make him look like a dark, hedgy-shaped blob, and you only know one 3ft hedgehog who runs at the speed of fast, who else is it gonna be?? So, that easily clears things up for Eggman and G.U.N, but Amy saw this emo-looking motherfucker in broad daylight. So ???

BACK TO SMELL. The idea that hedgehogs with poor eyesight live normally doesn’t really say that only they smell first and look second- it implies that no matter how good a hedgehog’s eyesight is, they’ll do this. 

So, here’s another fun-fact I’ve found, and will not illustrate with Sonic characters as that would be weird:
Hedgehogs do this thing called “anointing”. Basically, if they find a New Thing, they will make themselves smell like the new thing by biting it, then licking themselves. 
Meaning, when Amy hugged Shadow on Prison island, she was smelling for something like “prison island mixed with male hedgehog”. When she hugs Silver, not only are they once again in the same location, it’s… pretty fuckin dark. Then when she hugs werehog!Sonic, it’s dark, and he would obviously smell like Sonic. 

So, maybe Amy needs glasses, maybe she doesn’t! She probably just needs to start looking before she smells, but that would be a difficult habit for a hedgehog. 
Really, Sonic’s the one who’s overenthusiastic about finding new smells. And as much as I love throwing glasses on my faves, I feel like the “Amy needs glasses” h/c is too often used as a way to make fun of her, which obviously doesn’t sit well with me.

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(For @sixpenceee) (click on picture for captions)

Retinitis Pigmentosa (RP) is a genetic disorder caused by DNA mutation that effects the retina’s ability to process light. The disorder begins with a loss of night vision, then peripheral vision, then to the “pinhole vision” showed in the bottom right hand picture. Eventually, according to the American Academy of Ophthalmology, blindess results.

RP causes cells called rods and cones within the retina to die, resulting in the loss of color perception and central vision. As shown in the following diagrams, the Fundus is severely deteriorated: 

Normal Retina 

RP Retina 

Currently, there is no cure for this disorder. 

In Black & White

The human eye is one of nature’s most complex and sophisticated creations. The really amazing part of what your eye does is the transformation of light into electrical impulses. This is done by the photoreceptor cells in your retina.

There are two kinds of these cells. The rods and the cones. Your cones are responsible for all the colorful and vivid images you see. They are concentrated at the center of the retina, so when you look straight ahead, you see what the cones are showing you. The rods only see black & white. But they are more sensitive to light, and much better at detecting movement.

This gives rise to some interesting phenomena. You’re outside on a beautiful night. And then, out of the corner of your eye, you see a bright star. But when you turn that way, the star is gone. This is because what you saw from the corner of your eye was shown to you by the rods. When you turned, the star moved to the field of the cones, who, of course are not sensitive enough to show you that star. So in a way, now you are not seeing that which is already there. The eye truly sees a lot more than you realize.

So think about the last time you saw something out of the corner of your eye. A blurred image or a moving object. You turned towards it and it was gone. Next time, don’t turn. Your rods are trying to show you something.

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See the World through the Eyes of a Cat.

Artist Nickolay Lamm with the help of vets and ophthalmologists, presents his idea of the way a cat might view different scenes.

Major differences between our eyes and a cats are mainly their broader field of vision (approximately 200 degrees as opposed to out 180 degrees), as well as their lack of crispness and clarity in their sight, particularly at longer distances. 

The major trade off though is that their predatory eye sight can see far better and sharper in dim light. This is due to the various photo receptors in a cats eyes that we don’t have, particularly in having far more rod cells that are responsible for night vision.

Lastly, cats see colours differently to us, feline photo receptors are more sensitive to wavelengths in the blue-violet and green-yellow ranges. Hence why the cat images are slightly less vibrant.

Rhodopsin is a biological pigment in photoreceptor cells of the retina. It is the primary pigment found in rod photoreceptors.

There are about ~10⁷ rhodopsin molecules in each rod. And ~120×10⁶ rods in a typical eye. (And 5–6e6 cones.) When a few hundred “unphotobleached” rhodopsins interact with light, they become “photobleached”, open up, and that changes the shape of the rod cell. If the rod cell gets big enough, it is more likely to send a glutamate signal “down the line”.

Photoreceptors hyperpolarise to light. Therefore, gluatamate is released when there is a decrease in illumination.

Also your body replaces rods over time.

About 45 minutes after photobleaching, all the rhodopsin proteins will have returned to their closed shape.

COLOR VISION IS 300 MILLION YEARS OLD

Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively.

A fish eye from a primitive time when Earth was but one single continent has yielded evidence of color vision dating back at least 300 million years.  Analyzing the fossilized remains of a fish called Acanthodes bridgei that lived long before the dinosaurs, scientists discovered light-sensing “rod” and “cone” eye cells — the oldest ever found. being  the first discovery of vertebrate retinal fossils. The remains had been preserved under a thin coating of phosphate, analysis of the tissue provides the first record of mineralised rods and cones in a fossil. YAY!!!

New function for rods in daylight

Vision – so crucial to human health and well-being – depends on job-sharing by just a few cell types, the rod cells and cone cells, in our retina. Botond Roska and his group have identified a novel function for rod photoreceptor cells in the retina in daylight. Driven by cones and mediated by horizontal cells, rods help to increase contrast information at times when they are not directly sensing light. The retina thus repurposes its cells in different light conditions to increase the amount of visual information about the environment.

(Caption: Horizontal cells in the retina)

Task sharing in the retina seemed clear: Two different kinds of photoreceptor cells take on two different visual tasks. Rods allow us to see at night, cones operate during the day and enable color vision. However, the question as to why there are about 20 times more rods than cones in a human retina, when daytime vision is much more relevant for us, has usually led to a shrug of shoulders. It seemed a waste of resources.

Botond Roska and his group at the Friedrich Miescher Institute for Biomedical Research, could now show in a study published recently in Nature Neuroscience that the rods in mouse take on an important function during daytime vision as well.

The scientists showed that in bright light, the rods mediate a so called surround inhibition. Surround inhibition is an important feature in the retina because it allows not only to transmit information about whether a photoreceptor is exposed to light, but also about contrast. While the cone cells hyperpolarize in bright light and thus send a visual signal to the inner retina, the rods depolarize, inversely matching the activity pattern of the cone cells. The response in the rods is driven by cone cells and mediated through horizontal cells. These horizontal cells connect rods and cones through their dendrites and long axons, and at the same time form a mesh of connections among each other. The hyperpolarization of one cone thus leads to the depolarization of many surrounding rods.

During bright light conditions, the cells of the inner retina receive therefore information through two pathways: First through the well-established cone pathway, and second through this newly identified rod pathway. “We think that the surround information relayed to the inner retina through the rod pathway has different functional properties than the information obtained through the cone pathway,” comments Roska. “In any case it is fascinating to see how the retina repurposes the rod cells during bright light conditions to increase contrast information, at times when they are not directly sensing light.”

After all, these large numbers of rods don’t seem to be present in the retina in vain.

anonymous asked:

You know how in movies the hero is sometimes super fast, has keen senses etc. Do you think it's phiscally possible for someone to have beyond ordinary senses after being experimented with?

Well that depends on what sort of experiment you’re doing and what sort of senses we’re talking about. At the current point…. no. there are limits to human sensory perception that we can’t get across because we’re lacking the basic receptors for them. Say UV-light or ultrasonic noise. However if we abandon ‘what can science do today’ (which frankly speaking is a staple for superhero anything)…. then we can talk. 

For example, night vision could be achieved by giving someone a tapetum lucidum for example (like cats got) which would result in the same reflect-y eyes, or you could add more light detecting rod cells to the retina, however since your eyeballs provide limited space, more rods would almost certainly mean less cones so your night vision would come at the cost of your color vision. Also note that special senses in superhero context are almost always something that comes without a downside.

For example someone with very acute hearing (which we could do, you could if you had enough science-magic at hand, tamper with the sensor capacities of the ear enough to let a human hear a broader frequency spectrum than they currently do) is almost never shown being bothered by loud noises, or more bothered than your average human, when the thing is, if you can hear someone’s heartbeat from across the room, the dude in the train beside you listening to death metal via his headphones is going to bother the fuck out of you. 

Spore Power: Wetting Bacteria Makes Electricity And Robot Muscles

by Petti Fong

If dry bacteria spores of the genus Bacillus were boxers, commentators would say they punch above their weight.

When they dehydrate, the rod-shaped spores– dormant cells that help the microorganism survive tough environmental conditions and are naturally found in soil and vegetation—shrivel or curl like a leaf. Add some moisture and they straighten out again. Studies have shown that they can absorb water and expand with remarkable force. Now scientists say this phenomenon can be harnessed to use the microbes as a potential source of renewable energy or as muscles to make superstrong robots.

In research recently reported in the journal Nature Nanotechnology, a team detailed how they smeared spores on a flat piece of rubber and created a bacteria-powered generator.

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The microbes living on and in your skin enjoy shelter, moisture and the chemical building blocks they need for growth. Their turf is valuable, and they will fight to defend it.

Like most microbes typically found on skin, these bacteria don’t harm us, and they may protect us from treacherous intruders. Here, rod-shaped bacteria called Bacillus subtilis (purple) are locked in battle with a fungus that causes athlete’s foot (green). Like many kinds of bacteria, Bacillus subtilis cells can collect in orderly chains to form biofilms—cooperative communities that may improve self-defense. These rod-shaped cells have formed a blockade and are spewing toxic chemicals—a bold attack on an advancing colony of fungus.

The bacteria shown in this exhibition model, Bacillus subtilis, produce chemicals that kill other bacteria, as well as fungus. One strain releases an antibacterial blend called bacitracin—an ingredient in many over-the-counter antibiotic ointments. Under the right conditions, the population of Bacillus subtilis cells can double in about two hours!

Learn more amazing tales of your microbiome in the exhibition, The Secret World Inside You, open through August 2016. 

Ok so I know lots of other people have provided scientific explanations for the dress - and I’m gonna provide another simplified one. I’m a neuroscience student, and I research visual perception at my job, so you can trust me on this!

Basically: everyone genetically has slightly different ratios of colour receptors in their eyes, which results in everyone actually seeing colours slightly differently. Furthermore, everyone has slightly different amounts of the main protein that senses light intensity - called rhodopsin - in their rod receptor cells in their eyes (this is also due to genetics). So everyone had different sensitivity to light.

In pictures with dim lighting and directly inverse colours, such as the dress one, those differences between people are really noticeable. Light sensitivity is a part of this -  if you are less sensitive to light, you are less likely to notice the colours and see white and gold. If you are more sensitive, you see blue and black. It may also be a difference in blue channel cone expression.

Also, in this photo, there are likely optical illusion effects (such as after-image) can make it even harder to categorize the colours.

TL;DR everyone sees colours differently due to genetics, both sides are technically right, everyone chillax it’s all good!

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this took way too long! anyway this is my 4th and final gemsona!!! im super satisfied with her design and backstory wise. shes a bit shorter than lapis

she doesnt have a “typical” weapon, like lapis with her water manipulation. this does come at a cost as she needs to wield a physical weapon, like pearl early on, should the need arise. her light powers are super cool though and can be used in other ways

if need be, she can direct any light away from someones rod/cone cells in their eyes, rendering them blind until she stops. she can also use it as tactical cloaking to pass by enemies unnoticed or create illusions of objects or people.

benitoite is a very rare gem only found in benito california. beni occurred there naturally and was discovered by some early homeworld kindergarteners and injected with (sentient gem magic) basically to see what she would turn out like. unfortunately for them, she stayed undetected by homeworld gems after emerging whom she was distrustful (afraid) of. eventually she was taken in as a crystal gem and fought in the war.

her main homeboi is jelly