tag:blogger.com,1999:blog-5821098719340852065.post7292731245683091867..comments2024-03-25T09:31:36.926+01:00Comments on Furahan Biology and Allied Matters: Big Bad Flashy Fish (BBFF): the final answer to echolocation Sigmund Nastrazzurrohttp://www.blogger.com/profile/16449461215427527447noreply@blogger.comBlogger25125tag:blogger.com,1999:blog-5821098719340852065.post-13297591469983659232013-07-18T00:54:18.799+02:002013-07-18T00:54:18.799+02:00Andrew: thank you. You have posted several insight...Andrew: thank you. You have posted several insightful comments lately, but on old posts, so I wasn't too sure what to do with them (I am none too certain that people still read these old posts). It does seem as if you know what you are talking about though; send me an email if you would like to converse in more detail. Sigmund Nastrazzurrohttps://www.blogger.com/profile/16449461215427527447noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-63969209252151214282013-07-13T06:02:03.528+02:002013-07-13T06:02:03.528+02:00Echolocation has a very specific potential advanta...Echolocation has a very specific potential advantage that hasn't been mentioned here. Waveform control.<br /><br />Flashlighting is going to produce one or a few very specific wavelengths. If more than one wavelength is produced, you could vary the different wavelengths, but there's no obvious way (that I've thought of) to achieve stealth in this manner, other than the trick where the prey can't see the wavelength you're using.<br /><br />On the other hand, sound production in animals can be controlled with a great deal of precision, as parrots amply demonstrate. This is because you don't need specific molecules and protein complexes for each wavelength. There are two stealth echolocation tricks that I've come up with by taking advantage of this difference, and I believe one leads easily into the other.<br /><br />The first is simple mimicry. The echolocation pulse sounds like some ordinary noise in the environment. This relies on having an environment with a decent amount of noise, but that shouldn't be too hard. The big drawback with this is that it's probably going to be very suspicious if used continuously, so it would likely not be useful for navigation.<br /><br />The next trick is based on noise radar technology. This uses random noise on a very wideband frequency spectrum to hide this signal among background noise. This has large signal processing requirements, but could potentially be used continuously without being noticed until the echolocator is pretty close to its target, and would allow fairly safe navigational use. This would be difficult for other animals to detect for the same reason that white noise machines work.<br /><br />http://spie.org/x90215.xml <br />http://en.wikipedia.org/wiki/White_noise_machineAndrew Broekerhttps://www.blogger.com/profile/03455959935160897929noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-25592787636807862472012-10-31T02:28:29.712+01:002012-10-31T02:28:29.712+01:00It seems to me that the discussion is beginning to...It seems to me that the discussion is beginning to resemble sounds echoing between walls a bit. Anyway, on the subject of human echolocation, here is something I found and linked to in my first post on the subject. It seems that people can learn to use echolocation to an amazing degree. <br /><br />http://www.echolocaters.com/?page_id=111 Sigmund Nastrazzurrohttps://www.blogger.com/profile/16449461215427527447noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-49484733659455187042012-10-30T19:15:17.708+01:002012-10-30T19:15:17.708+01:00"Rodlox, perhaps I'm a freak of nature, b..."Rodlox, perhaps I'm a freak of nature, but I'm capable of detecting self-created echos in a suitable space, and gleaning some information about that space from the echo- whether it is a compact or volumnous space, covered in hard or soft surfaces, cluttered or empty. Of course it isn't echolocation, but is a means to gain information on one's environment."<br /><br />A lot of people can actually do that, given enough practice. It's just that the human body isn't as specialized for detecting the fine details in the reverberating sound (and hence, increase the quality of the echo) to the degree seen in bats and dolphins.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-15691893681373323212012-10-30T19:13:14.990+01:002012-10-30T19:13:14.990+01:00I think that this link may provide some food for t...I think that <a href="http://en.wikipedia.org/wiki/Human_echolocation" rel="nofollow">this link</a> may provide some food for thought...Evan Blackhttps://www.blogger.com/profile/10493966209787828900noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-29793916027762423512012-10-30T05:47:17.621+01:002012-10-30T05:47:17.621+01:00all things being equal, any hearing person can tel...all things being equal, any hearing person can tell if a basketball is being bounced in a small room, a large gymnasium, or an aircraft hangar.<br /><br />...but I wasn't referring to that. I was referring to the point of echolocation: finding things your size or smaller in a room. (can your self-created echoes tell you if you're about to walk into a chair?)<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-83465039126270007172012-10-29T17:20:48.902+01:002012-10-29T17:20:48.902+01:00Rodlox, perhaps I'm a freak of nature, but I&#...Rodlox, perhaps I'm a freak of nature, but I'm capable of detecting self-created echos in a suitable space, and gleaning some information about that space from the echo- whether it is a compact or volumnous space, covered in hard or soft surfaces, cluttered or empty. Of course it isn't echolocation, but is a means to gain information on one's environment.<br /><br />In regard to SOFAR channels, the SOFAR channel does seem to have a very large effect on sound propagation in the ocean. The closest analogy in terms of light that I can think of is something like a fibre-optic cable; I doubt such a phenomenon could present itself on a large scale in a natural environment on land.<br /><br />On the other hand, there is a phenomenon that could bolster flashlighting; eyeshine. The tapeta lucida employed by many animals for exactly the purpose of low-light vision act as naturally occuring retroreflectors, conveniently reflecting light back at a source. This gives a potential flashlighter the advantage of (a) being able to directly pinpoint the location of a prey item via eyeshine, and (b) potentially detect prey items at a greater range (or lesser illumination) than would be possible simply by illuminating the environment. Detection of eyeshine, specifically, is theorised to be the use of the Stoplight Loosejaw's flashlighting behaviour.<br /><br />One could argue that detection of eyeshine is a far more advantageous purpose for eyeshine than simple illumination (for example, other factors aside, this use is just as advantageous for a creature adapted to dark environments). Of course, there are still disadvantages, such as those that come with an active sense, etc.<br /><br />I did consider differences between sound and light propagation, but was unsure of the exact effects- I decided not to add another hazy point to an already hazy comment. I agree with Jan that light is not immune to such interference, but I would imagine that light will degrade much less in an Earthlike atmosphere than in water even in good visibility.<br /><br />~T.NeoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-90111524393800970862012-10-29T01:17:27.141+01:002012-10-29T01:17:27.141+01:00"If I may go a bit off-topic here, in a manne..."If I may go a bit off-topic here, in a manner that relates to some of the rambly stuff I have posted here previously; I know you have described the other planets in Furaha's system, and some astronomical traits of Furaha itself (axial tilt and soforth), but I cannot remember whether you have stated whether Furaha has any moons and what their attributes are. I can certainly understand if this information is intended only for publication in book form; I am asking about this issue because the presence of a moon (and thus of moonlight) is quite relevant to nocturnal animals."<br /><br />I agree. Neil Comins published a spec evo-related book, "What if Earth had Two Moons" in which he discusses the astronomic and biological effects of alternate arrangements of our solar system. According to this book, a second moon would have a huge impact on how bright a planet gets at night (assuming the moons are the same size). And studies on caenolestid and didelphoid marsupials have shown that a particularly bright moon can be lethal for such small, cryptic animals as these.<br /><br />--MetalraptorAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-37439679316648489612012-10-29T01:12:05.247+01:002012-10-29T01:12:05.247+01:00Ugh. I meant to comment on this earlier, but life ...Ugh. I meant to comment on this earlier, but life intervened and I'm only getting around to it now. I think mithril might be right when it comes to the lateral line being a better alternative to echolocation, given it can provide a lot more sensory information without giving away an animal's position.<br /><br />Actually, the fact that many marine fish have photoluminescent organs makes brings up the exact same problems as echolocators. In both cases you're emitting a beam of sensory information (light,sound) into the darkness essentially giving away your position to every predator out there. There has even been some suggestion that the large eyes of big, predatory squid are an adaptation to track down photoluminescent fish.<br /><br />Interestingly, Cracked Magazine, of all people, chipped in a little bit of useful information on the whole issue. They noted that the kind of sonar you see in most movies, where a pulse of sound is let out into the surrounding water to identify nearby objects, is not the type of sonar you normally see submarines you. Instead they use passive sonar, which is essentially sitting there and listening really, really hard. They do this for some of the exact same reasons you used for echolocators above.<br /><br />"It's also not a marine mammal thing, since seals don't echolocate."<br /><br />There has been some suggestion in the past of echolocation in pinnipeds, but in every case the evidence has not stood up to scrutiny. It has been suggested that the reason echolocation never evolved in pinnipeds is because they spend at least some time on land, and its difficult to attune the auditory system to the degree of sensivity needed for echolocation AND maintain function in both environments.<br /><br />"Instead, they use a trick: there is an antenna protein in their eyes that is sensitive to red light, and this transferred the energy to the pigments sensitive to blue and green light that the fish does have"<br /><br />Something like this could actually make echolocation feasible in an alien environment. Bats today are able to echolocate at different frequencies, such as how some fruit bats are able to echolocate at frequencies audible to the human ear. All you would need to do is echolocate at a frequency that most predators cannot hear, and you can maneuver without attracting attention. Of course, some predator would eventually specialize in picking up your signals, and an evolutionary arms race would begin.<br /><br />--MetalraptorAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-66232476187703165732012-10-27T15:10:58.448+02:002012-10-27T15:10:58.448+02:00SN: Maybe this will help http://www.me.psu.edu/lam...SN: Maybe this will help http://www.me.psu.edu/lamancusa/me458/10_osp.pdf <br />But I think that visibility is even more vulnerable to "additional disadvantages", especially in waterJannoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-36613808713726505402012-10-27T11:56:16.870+02:002012-10-27T11:56:16.870+02:00I agree with T.Neo's observation about the gap...I agree with T.Neo's observation about the gaps in speculative biology: often there is indeed too little information to state whether an idea is workable or not. From that point on we have to rely on an intuitive understanding of physics and biology.Of course, that can give rise to differences in opinion; personally, I enjoy the exchange of ideas.<br /> As for the decrease in intensity of a signal to uselessly low levels, that must be the case. The thing is whether the distance involved overlaps the range useful to animals. Sound and light decrease over distance in a similar manner, but sound may have an additional disadvantage: Being mechanical in nature you would think that there would be friction involved, diminishing the intensity in addition to the square-law effect. How much this affects the diminution of intensity I do not know (a quick search did not reveal much). Sigmund Nastrazzurrohttps://www.blogger.com/profile/16449461215427527447noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-65546115127883356482012-10-27T00:34:41.796+02:002012-10-27T00:34:41.796+02:00if it were that easy to detect echoes, everyone co...if it were that easy to detect echoes, everyone could do it. (we humans can determine the direction a sound's coming from - "the tv on my left" - but only a handful of people are able to do any degree of echolocation)<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-52247327368769244512012-10-26T16:10:50.800+02:002012-10-26T16:10:50.800+02:00Anonymous: That distance could be extremely long i...Anonymous: That distance could be extremely long in some cases<br />http://en.wikipedia.org/wiki/SOFAR_channel<br />Maybe it is obvious, but light and sound propagate very differently in different enviroments and even type of vegetation could completely change the advantages of respective sense.Jannoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-79567111914292227542012-10-26T15:14:55.922+02:002012-10-26T15:14:55.922+02:00My knowledge of echolocation isn't all that go...My knowledge of echolocation isn't all that good, but simply making a noise- of the right sort and with the right sort of 'hardware' to detect echos, [i]will[/i] give you information about your environment, even if it isn't very good information. <br /><br />My knowledge of the US Navy isn't all that good either, but I'm not entirely sure how their operations invalidate what should be something based in fairly simple physical laws; signals diminish in intensity with distance, and at a certain distance it will become impractical or impossible to detect that signal. Obviously the specific signal, situation and sensor all change the dynamic of the scenario and thus its outcome, but that doesn't invalidate the basic principle.<br /><br />~T.NeoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-32077666597400155632012-10-26T00:48:34.296+02:002012-10-26T00:48:34.296+02:00>echolocation confers a specific sort of rangef...>echolocation confers a specific sort of rangefinding ability <br />...when advanced enough, sure. but just making noise, is more likely to attract predators, than to tell you anything.<br /><br /><br />>but there must surely be a distance from an emitter at which point the signal from it diminishes to a level either intrinsically undetectable or undetectable against background <br />...I'm sure the US Navy wishes that were true, particularly where whales are concerned.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-40968426293441399752012-10-25T19:45:21.167+02:002012-10-25T19:45:21.167+02:00Sigmund; I definitely understand where you are com...Sigmund; I definitely understand where you are coming from, and indeed the difficulty of calculating the various costs and benefits was on my mind when writing my comment. The more I think of speculative biology topics, the more I feel that everything is either fairly well based on the laws of physics, geology, planetology, chemistry, etc... or its likelihood or evolutionary cost/benefit is difficult to pin down and is thus disputed...<br /><br />Of course it is not impossible, or difficult, to perform range-finding with vision (after all, we do it constantly). My original point was that echolocation confers a specific sort of rangefinding ability and thus a specific sort of advantage. Of course, echolocation comes with a certain set of disadvantages over vision (and thus presumably, flashlighting). That they do work differently, of course, is relevant to how they evolve- but I would imagine that even a meagre understanding of exactly how those differences might affect the evolution of flashlighting would likely take a lot of thought and research.<br /><br />Your point that other animals have better hearing than we do is a very good one; however, it should also be pointed out that there are also animals with better eyesight. <br /><br />I was thinking more in terms of it simply becoming more physically difficult to detect sound at a certain distance than light; perhaps I am simply talking nonsense, but there must surely be a distance from an emitter at which point the signal from it diminishes to a level either intrinsically undetectable or undetectable against background <br />'noise'. At night, it's obviously relatively dark, but there's nothing preventing usual environmental sound <br />production- thus the level of visual 'noise' should be lower than the level of auditory noise, and it should be easier to detect a light source at a distance (as an example of this sort of principle, it's far more difficult to make out a torchlight at a distance in daylight, when it's generally brighter).<br /><br />I would be willing to bet that the evolutionary and physical limits of eyes are the reason why the stoplight loosejaw uses flashlighting in the first place; it's a deepsea creature that would presumably already have rather well-developed eyes, and developing them further would incur heavier disadvantages than flashlighting.<br /><br />Of course, a whole plethora of animals seem to get along fine with vision in low-light environments, such as at night. My gut feeling is that the costs of flashlighting become problematic before the costs of enhanced vision do, but I agree that from an actual quantitative point of view, the costs and benefits are difficult to ascertain.<br /><br />Apologies for yet another long post,<br />T.NeoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-88054826620945669952012-10-24T05:40:52.988+02:002012-10-24T05:40:52.988+02:00Bioluminescence is fascinating topic for speculati...Bioluminescence is fascinating topic for speculative biologists. Have you known that there are "firefly tourism" in southeast Asia? http://www.youtube.com/watch?v=4dg8HEn1CVc<br /><br />I can think of no reason why bioluminescence on land must be limited only to small creatures. With bigger animals, there could be also more complex behaviour. Predators hunting in packs can use bioluminescence to disorient their prey instead of revealing their position. Social animals can use it to a complex communication (there are some similar predators on Nereus I think). <br /><br />The energy expenditure of bioluminiscence could be in fact used for display of health and strength. Think about the abundance of energy spending and "unnatural" complexity in mating rituals of birds. So I think that bigger animals would not just use bigger "lamps", but also more elaborate shows.Jannoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-88282371174132748202012-10-22T21:33:31.877+02:002012-10-22T21:33:31.877+02:00T. Neo: thank you for these well-thought out comme...T. Neo: thank you for these well-thought out comments. This topic certainly seems to bring out the essayist in all respondents!<br /><br />Mind you, I haven't said that all oceans should be filled with 'flashlighting animals'. I too have my problems with the concept as an overall winner. The very fact that it exists is wonderful in itself, though, and it deserves consideration. The real problem may be that it is very hard to weigh al the pros and cons. Just for the sake of getting to the heart of the matter, let me see if I can counter some of your arguments.<br />- flashlighting does not tell you range by itself. True, but as it makes use of vision, the resolution of the information bounced back is much higher. Animals using it will have eyes already capable of combining images to infer range anyway. <br />- both flashlighting and echolocation share the disadvantage of being very noticeable from a distance. I share the feeling that this works better for light, but the reason for that might be that we as humans simply have very good eyesight but relatively poor hearing. Is there an objective scale to compare the two. <br />- You raise he point that you can use dimmer light if you enhance the sensitivity of sight. True again, but there are physical and biological limits to increasing eye sensitivity. Eye sensitivity to a large extent comes down to eye size, and beyond a certain point that development stops. You cannot keep on increasing sensitivity, so there is a point at which adding a bit of light will provide an additional benefit.<br /> I am not making all this up to be difficult; your points are good, but I think that many of the costs and benefits are hard to calculate. Without that, it becomes speculative biology... ;-) Sigmund Nastrazzurrohttps://www.blogger.com/profile/16449461215427527447noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-55995685297693894262012-10-21T20:32:48.305+02:002012-10-21T20:32:48.305+02:00There may be various reasons why 'flashlightin...There may be various reasons why 'flashlighting' is less advantageous than echolocation; <br /> <br />- Echolocation involves producing vibration, which seems to be something that animals do rather easily. Bioluminescence requires the transformation of chemical energy into light (the efficiency of this process is not simply relevant to this discussion, but relevant to discussion of bioluminescence as a whole). <br /> <br />It may be that echolocation is more efficient than 'flashlighting' in terms of sensor return for energy expended. <br /> <br />- Echlocation tells the<br />echolocator the range to an object simply as part of the mechanism itself. Flashlighting does not, due to the much higher speed of light. <br /> <br />- Light can carry extremely far; a dark environment may be just as noisy as a light one, but a point of light at night will be very easy to detect; likely not disrupted easily by environental sources or wind, etc. This compounds the problem of making oneself conspicuous by using an active sense. While being Big and Bad, as you have discussed, does help, I do not feel that it removes the problem entirely, especially in regard to detection by prey items. <br /> <br />A torch beam can only illuminate things usefully out to a certain distance, but can be detectable from a much greater distance. If your prey detect you long before you have even entered their vicinity, you are at a huge disadvantage. <br /> <br />- Vision is an extremely prolific sense, and thus such detection of your torch beams should be rather easy. While the prey items of echolocators may not by any means be deaf, vision is generally more prolific than hearing and more useful even at a simpler stage of development. You can, of course, use a wavelength of light that none of your prey items can see (efficiency of producing it permitting), but there are limitations to this as well. It should be considered that none of the prey items of the stoplight loosejaw can see the wavelengths it emits at, because the environment in which they live is extremely deficient in those wavelengths. <br /> <br />These issues can also be solved somewhat by having a dimmer beam, and more acute eyes to detect the reflections... but this brings the discussion down the pesky path of why you would use a flashlight at all if you can just enhance the acuity of your eyes to enable passive sight in dark environments- which would eliminate any issues with 'flashlighting'. <br /> <br />Even if the energy budget of throwing such a beam is acceptable to the animal, and the use of energy is efficient enough, it is still a use of energy, and I would bet that a flashlight will use more energy than an eye adapted for night vision would. <br /><br />If the reason for the absence of echolocation in fish is the presence of decent passive senses, than the higher energy requirements and increased evolutionary complexity of 'flashlighting' may be what precludes its abundance. <br /> <br />The loosejaw fish is an organism in a quite light deficient environment- the deep sea, that has stumbled through a number of lucky evolutionary events that allow it to use 'invisible' bioluminescence to spot prey.<br /><br />If I may go a bit off-topic here, in a manner that relates to some of the rambly stuff I have posted here previously; I know you have described the other planets in Furaha's system, and some astronomical traits of Furaha itself (axial tilt and soforth), but I cannot remember whether you have stated whether Furaha has any moons and what their attributes are. I can certainly understand if this information is intended only for publication in book form; I am asking about this issue because the presence of a moon (and thus of moonlight) is quite relevant to nocturnal animals.<br /><br />Regards,<br />T.NeoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-526416304292591312012-10-21T11:37:35.732+02:002012-10-21T11:37:35.732+02:00Mithril: that seems certainly possible, and might ...Mithril: that seems certainly possible, and might explain differences between marine mammals. I wonder what the largest range is at which the lateral line system can work. You would expect system to provide more benefit as the range increases, so it would be nice to compare ranges under water of various senses.<br /><br />Arachnus: Producing sound is probably not very costly, so I would expect it can be generated in many ways. If I were a predator I would prefer a system that I could also turn off. <br /> As for producing sound at frequencies inaudible to others, that would work. But the range of hearing is already very wised in many animals, so it might not be easy to find a high frequency range that your prey cannot (yet) hear. If it can hear it just a bit, it will evolve quickly to improve that sense. <br /><br />Evan (1): Bioluminescence is definitely worth much more consideration. I thought about writing on it, but at present I am still amazed at the many paradoxes it seems to offer (such as that glows appear to attract and flashes appear to repel; can't predators adapt?)<br /> I picked out only one use of bioluminescence, the searchlight, because it forms a nice parallel to echolocation. Read the review I liked to and be surprised. But the 'offensive searchlight mode' seems to be fairly rare. It exists though, and in speculative biology that is a pretty argument, I should think... But I have my doubts about its applicability, as the last lines of my post show. <br /><br />Rodlox: that is a good point as far as vertebrates are concerned. I do not know how many other groups of fish have bioluminescence; there appear to be many. As for invertebrates, bioluminescence seems almost part of their basic kit in the sea.<br /><br />Evan (2). Luminescent land squid (or, the film 'Monsters'). May I say that I still like the concept, even though it's been done to death. Sigmund Nastrazzurrohttps://www.blogger.com/profile/16449461215427527447noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-58731531901049422142012-10-21T03:54:45.795+02:002012-10-21T03:54:45.795+02:00Or-- dare I say it-- land squid? ;)Or-- dare I say it-- land squid? ;)Evan Blackhttps://www.blogger.com/profile/10493966209787828900noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-23624472429964170022012-10-21T02:41:57.290+02:002012-10-21T02:41:57.290+02:00I have a feeling that a big part of why biolumines...I have a feeling that a big part of why bioluminesence is rare on land (on Earth), is because the clade who went from water to land didn't have it.<br />{neither the lungfishes nor coelocanths have anything that would function as a storage place for bioluminesent chemicals or bacteria - though coelocanths' eyes seem made for *detecting* such light)<br /><br />maybe if something like loosejaws or viperfish were to start making (mudskipperish) invasions of the land - at night, to dodge some predators and dehydration - we might end up with Flashlight Snakes and Glow-Spot Eels.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-35120462627245306322012-10-21T01:40:39.932+02:002012-10-21T01:40:39.932+02:00I agree with mithril that the most likely reason t...I agree with mithril that the most likely reason that fish haven't developed echolocation is because they have other lines of sensory input in place that solve the same problems. The lateral line sense and their occasional modification into electroceptors do just fine in helping fish detect their surroundings. And there is plenty of evidence pointing to cetacean echolocation, especially in toothed whales, so there must be <i>some</i> pressure for it.<br /><br />Bioluminescence is a subject that could (and probably should) get treatment all its own, especially given the complexity of the photophore. As far as its treatment in this post, one of the first things I wonder about is the brightness of the light, and therefore the range of benefit from these bioluminescent 'flashlights'.<br /><br />When I look at pictures of bioluminescent fish the bright spots are certainly apparent, but they don't seem to radiate much light. As far as I understand it, that light is only useful in helping a fish catch its prey with more precision at the last moment, rather than spotting prey at a distance. So I call power and range into question. Could a creature actually make bright beams of light shine outward on prey with enough intensity to spot prey at a distance? Is this physically possible?<br /><br />My second thought is motivation. Why not use other senses that will help you find prey without broadcasting your presence? What if it doesn't care about being seen? If it has poisons or other predatory deterrents, then it has little to fear and the only question is the physical possibility of its 'flashlights'.<br /><br />Arachnus, the idea of producing sound at frequencies outside of detection can be problematic. Even if it's outside the ear's sensitivity it creates a wave of pressure (that's what sound is) that could eventually be detected by others.Evan Blackhttps://www.blogger.com/profile/10493966209787828900noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-56319489708962320832012-10-20T00:21:17.297+02:002012-10-20T00:21:17.297+02:00Reading through the paragraphs on bioluminescence,...Reading through the paragraphs on bioluminescence, an idea struck me: could it be possible these echolocators have developed some kind of system that constantly produces sound? It could be tied to their respiratory system, like vocal cords that vibrate as the animal breathes in and out. <br /><br />As I read about the dragonfish, I had another thought. These animals could produce sound at different frequencies that may be inaudible to predators or prey.Arachnushttp://s1.zetaboards.com/Conceptual_Evolution/profile/1699129/noreply@blogger.comtag:blogger.com,1999:blog-5821098719340852065.post-27712275037992629012012-10-19T22:25:47.331+02:002012-10-19T22:25:47.331+02:00personally, i think the reason fish didn't evo...personally, i think the reason fish didn't evolve echolocation was because they evolved the vibration end electrical field sensitive <a href="http://en.wikipedia.org/wiki/Lateral_line" rel="nofollow">Lateral Line</a> early on. Lateral lines are hyper sensitive to the changes in the environment that other animals make just by moving, so they have little evolutionary pressure to evolve an active sense like echolocation.<br /><br />for fully aquatic mammals like Cetaceans, which don't have such a sense, evolution would have put pressure on sight, smell, and hearing. from paleontological evidence, early whales didn't have an active component to echolocation, and seem to have had a stronger reliance of sight and smell. presumably however their sense of hearing was acute though. somewhere along the line they developed the ability to enhance their own vocalizations and began to rely on those more. while the fossil record is fairly complete for understanding the gross physical evolution between land dwelling animal to fully aquatic animal, i'm afraid it is still very spotty regarding the evolution of their senses.<br /><br />most other aquatic mammals seem to be (from what has been found so far), far more recent than cetaceans. most other aquatic mammals also are under different pressures. Pinnipeds (seals) aare hunters, but most don't go deeper than the twilight regions.. and we have examples of a form of 'proto-echolocation' for the ones that do. <br />Sea cows and dugongs are herbivores, and don't need echolocation to find food.<br />and Otters don't hunt deep enough to need anything other than vision. mithrilhttps://www.blogger.com/profile/03088999203605302318noreply@blogger.com