A++ Cephalopod Investigator
So I spent some time doing drawings of cephalopods today
End results will be adoptables for Aramii, but I can post the sketches here if you guys want to see, once I scan them. Or y'all can just go find me on deviantart? I'm ~Crocuta-Crocuta
SO ANYWAYS my point was I also found some things out that I decided to pass on right so are y'all listening?
So I noticed first of all these things about tentacles: octopuses, squid, and cuttlefish all have very different tentacles. Squid have very skinny and almost flat tentacles. Octopuses have the sort of round ones with flat sucker-areas, but cuttlefish seem to have the reverse, with flat on the 'top' and wedge-shaped below. Also the way their tentacles behave are different. Squid and cuttlefish tend to move all their tentacles together - symmetrically. Octopuses, unless they are using their tentacles to swim, move them all separately, even when 'walking' on the bottom. This makes sense as I have heard before that octopuses actually have a lot of their neurons in their tentacles - so each tentacle essentially has a sort of brain controlling it. In fact, if you cut it off (they grow back) the disembodied tentacle will continue to move around on its own, and if it encounters food, will try to move it up to where it thinks the octopus's mouth is. Squid and cuttlefish may have to control all their tentacles from a central nervous system, which would make it difficult to control that many limbs separately all at once.
Also: cephalopod eyes are very different from mammalian eyes. In fact, they probably evolved separately, and any resemblance is due to convergent evolution (for those of you who did not learn much about evolution in school or have forgotten, 'convergent' evolution is when two different organisms evolve a similar trait, usually to deal with a similar problem; for example, panda's possession of a thumb-like muscle in their hands is an example of convergent evolution, as the ancient ancestors they share with today's primates did not have thumbs; both species evolved them separately; in the case of eyes, we all evolved eyes because sensing light is a vast advantage in almost any environment). Go look at some cephalopods, their eyes are fascinating and all wavey! It's easiest to see in cuttlefish.
Since I'm talking about this anyways, I will take a brief moment to address some 'evidence against evolution': the concept that the eyeball must have been created all at once, since individual parts of it would not function without the rest, so it could not have been created in small steps over time a la evolution.
Now, this is untrue, first of all. It is true that without the whole structure of the eye, we would not see as well as we do; but all we really need is either the cones or the rods, and for them to have some sort of exposure to light. This doesn't actually require a lense or eyeball of any sort - after all, light travels through your skin easily enough, even if it's not transparent; ever covered a flashlight with your hand? Or just look at your hand and observe that you can see veins in it. Think if the cones and rods were about where the veins are. They would get quite a bit of light. And over time, it would be advantageous for them to get more light, so those with more translucent skin in those areas catch more food and get to produce more babies, and so on.
And there are certainly what one might call 'mini-steps' towards the 'fully developed' eye all around us. Go get an earthworm. Place it on a thin layer of soil (not enough for it to burrow!) that is evenly heated, in a lighted area (not too strong - don't shine a desklight right on the poor thing or something - just do it in a room with the light on; also, be sure the room is reasonably warm, and that the light is not a source of heat, at least not at the distance you have the worm from it). Then, hold something over the container with the worm in - something that will block the light - say a piece of cardboard - such that it throws a shadow on half of the worm or so, and the other half of the worm is still in the light. See what happens.
Try this a few times if you want. Record results! Remember to let the worm rest a bit in between trials so the soil remains an even temperature and the worm does not get exhausted. Put it back where you found it when you're done.
Now, if you don't want to actually do this (I have done it, myself, and TBH it is pretty boring unless you are a big fan of worms, which I happen to be) I will tell you what happens: almost always, the worm will immediately move in the direction of the shadow and get its entire self under it.
Feel free to examine your worm (gently please). Do you see eyes on it? No, you do not. (If you do, please put that down, it is not an earth worm, IDK what you are holding). This is because worms do not, in fact, have eyes. But they can sense the light. This is not because they are psychic (although I am not discounting the possibility that earth worms can also be psychic, it is irrelevant here though). It is because despite lacking eyes as we know them, they do have nerves that can sense light. And that is what the beginning of the physical trait we know as an 'eye' is. That is where it started in every animal that today has an eye. A distant ancestor could, like the worm, sense light, with nerves that are probably very similar to what we humans (as well as many, many mammals) have all over our bodies that sense other things, like heat, cold, pain, and pressure.
So why are eyes today all so similar? Well, some, like mammal eyes, are an example of divergent evolution; a common ancestor developed the eye, and then several species evolved from that ancestor, all evolving their own variations on that design. Some are really weird and different, like goat eyes. Others are examples of convergent evolution, like the cuttlefish I was talking about earlier. As to why they all look fairly similar - well, some don't. Go take a look at a compound eye, like an insect has. But many of them do look similar, and eyes are always - to my knowledge - located as close as is convenient to the central nervous system (i.e. the brain). Why is this? Well, obviously it must be the design that works best. Things like the squished-egg shape of the eye and curved lenses allow better and more clear sight, giving an obvious advantage. Contracting muscles around the pupil and eyelids allow for protection of the eye. Location close to the central nervous system allows visual information to be relayed quickly to the neurons that make decisions; so it's the most natural place for the light-sensing nerves to 'gather'. So these things come up often.
I will also interject here something you may or may not know. This is to get you thinking about evolution the right way, if you haven't had much exposure to it. In popular culture, the common concept is that humans are 'highly evolved'. To be honest, that means nothing. Everything on earth today went through as many millenia of evolution as we did. Some, like sharks, have stayed the same for a long time. It is true we have gone through a lot of changes, and our brain does things that we are not sure other animals' brains can do, although we are starting to see that maybe many of them can. But really the only fair thing to say is that we have evolved the most complex social system.
"But we can see in color," you say. "We can use tools. We can do math. Other animals cannot do these things!"
No, some cannot. But some can do more. Many, many things that live in the water - like cephalopods for example, but even 'little' things like shrimp - can see light polarization. It's difficult for many people to even imagine what 'light polarization' is, since we cannot detect it (except some people - using a specific trick - and then you can only see it going in one direction). Many marine animals see it as clearly as the standard human sees color; it's weaved into their markings, camouflage, and communication systems.
We have no need to see light polarization. So we never evolved it, or if we once had it, we lost it.
Similarly, most animals have no need of math, as they do not live in a social system that requires they use it. However, many predators can triangulate (using two known landmarks to estimate the distance to something that is visually between them and space-wise beyond them), to an exactness that humans, in general, cannot.
Alright, abrupt ending, but I must go to sleep now. I would have gone earlier but there was some goddamn coyote howling outside, which is scary enough when you haven't just been watching Noroi: The Curse. I'm still going to have to put on some TV while I fall asleep. I blame wild canines for all my problems.
Also anobjectinspace. This is his fault as well somehow. The coyote was probably him. STOP HOWLING OUTSIDE MY WINDOW TOPHER.
End results will be adoptables for Aramii, but I can post the sketches here if you guys want to see, once I scan them. Or y'all can just go find me on deviantart? I'm ~Crocuta-Crocuta
SO ANYWAYS my point was I also found some things out that I decided to pass on right so are y'all listening?
So I noticed first of all these things about tentacles: octopuses, squid, and cuttlefish all have very different tentacles. Squid have very skinny and almost flat tentacles. Octopuses have the sort of round ones with flat sucker-areas, but cuttlefish seem to have the reverse, with flat on the 'top' and wedge-shaped below. Also the way their tentacles behave are different. Squid and cuttlefish tend to move all their tentacles together - symmetrically. Octopuses, unless they are using their tentacles to swim, move them all separately, even when 'walking' on the bottom. This makes sense as I have heard before that octopuses actually have a lot of their neurons in their tentacles - so each tentacle essentially has a sort of brain controlling it. In fact, if you cut it off (they grow back) the disembodied tentacle will continue to move around on its own, and if it encounters food, will try to move it up to where it thinks the octopus's mouth is. Squid and cuttlefish may have to control all their tentacles from a central nervous system, which would make it difficult to control that many limbs separately all at once.
Also: cephalopod eyes are very different from mammalian eyes. In fact, they probably evolved separately, and any resemblance is due to convergent evolution (for those of you who did not learn much about evolution in school or have forgotten, 'convergent' evolution is when two different organisms evolve a similar trait, usually to deal with a similar problem; for example, panda's possession of a thumb-like muscle in their hands is an example of convergent evolution, as the ancient ancestors they share with today's primates did not have thumbs; both species evolved them separately; in the case of eyes, we all evolved eyes because sensing light is a vast advantage in almost any environment). Go look at some cephalopods, their eyes are fascinating and all wavey! It's easiest to see in cuttlefish.
Since I'm talking about this anyways, I will take a brief moment to address some 'evidence against evolution': the concept that the eyeball must have been created all at once, since individual parts of it would not function without the rest, so it could not have been created in small steps over time a la evolution.
Now, this is untrue, first of all. It is true that without the whole structure of the eye, we would not see as well as we do; but all we really need is either the cones or the rods, and for them to have some sort of exposure to light. This doesn't actually require a lense or eyeball of any sort - after all, light travels through your skin easily enough, even if it's not transparent; ever covered a flashlight with your hand? Or just look at your hand and observe that you can see veins in it. Think if the cones and rods were about where the veins are. They would get quite a bit of light. And over time, it would be advantageous for them to get more light, so those with more translucent skin in those areas catch more food and get to produce more babies, and so on.
And there are certainly what one might call 'mini-steps' towards the 'fully developed' eye all around us. Go get an earthworm. Place it on a thin layer of soil (not enough for it to burrow!) that is evenly heated, in a lighted area (not too strong - don't shine a desklight right on the poor thing or something - just do it in a room with the light on; also, be sure the room is reasonably warm, and that the light is not a source of heat, at least not at the distance you have the worm from it). Then, hold something over the container with the worm in - something that will block the light - say a piece of cardboard - such that it throws a shadow on half of the worm or so, and the other half of the worm is still in the light. See what happens.
Try this a few times if you want. Record results! Remember to let the worm rest a bit in between trials so the soil remains an even temperature and the worm does not get exhausted. Put it back where you found it when you're done.
Now, if you don't want to actually do this (I have done it, myself, and TBH it is pretty boring unless you are a big fan of worms, which I happen to be) I will tell you what happens: almost always, the worm will immediately move in the direction of the shadow and get its entire self under it.
Feel free to examine your worm (gently please). Do you see eyes on it? No, you do not. (If you do, please put that down, it is not an earth worm, IDK what you are holding). This is because worms do not, in fact, have eyes. But they can sense the light. This is not because they are psychic (although I am not discounting the possibility that earth worms can also be psychic, it is irrelevant here though). It is because despite lacking eyes as we know them, they do have nerves that can sense light. And that is what the beginning of the physical trait we know as an 'eye' is. That is where it started in every animal that today has an eye. A distant ancestor could, like the worm, sense light, with nerves that are probably very similar to what we humans (as well as many, many mammals) have all over our bodies that sense other things, like heat, cold, pain, and pressure.
So why are eyes today all so similar? Well, some, like mammal eyes, are an example of divergent evolution; a common ancestor developed the eye, and then several species evolved from that ancestor, all evolving their own variations on that design. Some are really weird and different, like goat eyes. Others are examples of convergent evolution, like the cuttlefish I was talking about earlier. As to why they all look fairly similar - well, some don't. Go take a look at a compound eye, like an insect has. But many of them do look similar, and eyes are always - to my knowledge - located as close as is convenient to the central nervous system (i.e. the brain). Why is this? Well, obviously it must be the design that works best. Things like the squished-egg shape of the eye and curved lenses allow better and more clear sight, giving an obvious advantage. Contracting muscles around the pupil and eyelids allow for protection of the eye. Location close to the central nervous system allows visual information to be relayed quickly to the neurons that make decisions; so it's the most natural place for the light-sensing nerves to 'gather'. So these things come up often.
I will also interject here something you may or may not know. This is to get you thinking about evolution the right way, if you haven't had much exposure to it. In popular culture, the common concept is that humans are 'highly evolved'. To be honest, that means nothing. Everything on earth today went through as many millenia of evolution as we did. Some, like sharks, have stayed the same for a long time. It is true we have gone through a lot of changes, and our brain does things that we are not sure other animals' brains can do, although we are starting to see that maybe many of them can. But really the only fair thing to say is that we have evolved the most complex social system.
"But we can see in color," you say. "We can use tools. We can do math. Other animals cannot do these things!"
No, some cannot. But some can do more. Many, many things that live in the water - like cephalopods for example, but even 'little' things like shrimp - can see light polarization. It's difficult for many people to even imagine what 'light polarization' is, since we cannot detect it (except some people - using a specific trick - and then you can only see it going in one direction). Many marine animals see it as clearly as the standard human sees color; it's weaved into their markings, camouflage, and communication systems.
We have no need to see light polarization. So we never evolved it, or if we once had it, we lost it.
Similarly, most animals have no need of math, as they do not live in a social system that requires they use it. However, many predators can triangulate (using two known landmarks to estimate the distance to something that is visually between them and space-wise beyond them), to an exactness that humans, in general, cannot.
Alright, abrupt ending, but I must go to sleep now. I would have gone earlier but there was some goddamn coyote howling outside, which is scary enough when you haven't just been watching Noroi: The Curse. I'm still going to have to put on some TV while I fall asleep. I blame wild canines for all my problems.
Also anobjectinspace. This is his fault as well somehow. The coyote was probably him. STOP HOWLING OUTSIDE MY WINDOW TOPHER.