Are octo's sensitive to sound?

Discussion in 'Physiology and Biology' started by Omega, Nov 24, 2011.

  1. Omega

    Omega GPO Registered

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    Hi guys, I know I've been MIA for a while but I'm considering setting up a new octo tank and was wondering how sensitive octos are to sound? The only room I have available for one would be in the same room as my "theater." I wasn't sure if octos would be sensitive to surround sound in a room..I watch a lot of loud actions films.
     
  2. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Somewhere, and I will see if I can google to find it, we had a good discussion on this that included the frequency ranges that octopuses "hear" (older thinking suggested the did not have an "ear" but more recent studies found an equivalent and tested for frequencies that can be detected). As I recall the member was concerned about keeping an octopus where he played an instrument but I don't remember the details.

    Here is one of the discussions that leads to the announcement of proving they CAN hear but not the discussion I am trying to find.

    I think this is the thread I was recalling but there is less discussion than I remembered.
     
  3. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

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    I play video games loud and i blast movies on my surround sound that is in the same room as all my octos, I live in a one room house, and it has never seemed to bother them.
     
  4. Level_Head

    Level_Head Vampyroteuthis Registered

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    As I recall, the octopus species that were tested have a relatively modest hearing ability, centered around 600Hz. The range is narrow (and somewhat lower than the 1500Hz range for one tested squid species). They don't have ears, per se, but hear through vibrations picked up by sensitive hairs in the statolith, the same organ that gives the octopus an extraordinary sense of gravity and acceleration.

    I would not be surprised to find that the hearing ability varies significantly between species of octopus.

    This hearing ability was important to me, as I was working on a novel about a future evolved octopus society, and I wanted to make certain that a limited hearing ability was a reasonable thing. Similarly, I was happy to learn that not all octopuses are colorblind.
     
  5. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Speaking of frequencies, does anyone know of tone generating app where you can set the frequency. I would like PlayBook vefsion but would be happy with an android flavor
     
  6. beccalopod

    beccalopod Cuttlefish Registered

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    They most definitely can detect sound, but not the same way we do. Since sound is just vibrations, they feel it that way, the same way we can feel a very loud bass. I would just recommend not using a sub-woofer, and not putting it up so loud that things start to rattle.
     
  7. Level_Head

    Level_Head Vampyroteuthis Registered

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    Thoughts on Octopus Hearing

    They definitely feel the sound, but it is more complex than the way that humans pick up loud bass vibrations. That latter is done through touch/pressure sensing, as the vibrations become low-frequency enough to be perceived as sensate motions of tissues.

    Octopuses (at least some) can feel vibration as you're describing, but that's not the only method. They also have a hearing organ — or at least an organ that seems to provide hearing along with other functions. As with mammals, hearing is connected to balance. In our case, the three-semicircular loops (one each in the X, Y and Z planes) provide sensing of motion, and we adapted that same fluid to pick up vibrations with fine hairs tuned to different frequencies. As I understand it, the octopus (like cephalopods in general) has a small chamber somewhat similar, with bits of mineral resting on fine hairs that are very sensitive to motion of the central piece.

    When the octopus moves, the pressure on those hairs change, giving it a very good sense of acceleration. Orientation, too, is well maintained; the octopus uses this organ to keep its eyes aligned horizontally, so that it can properly judge the polarized light. (This is similar to your polarized sunglasses; when you tilt your head, the light looks "wrong.")

    Apparently, at least for some species and some frequency ranges, the octopus can use its statocysts to sense sound vibrations through these same hairs. Those frequencies have been measured around the 600Hz range for some octopuses.

    This understanding is relatively recent. Older papers, such as this one from 1960, suggest that octopuses might be deaf:
    http://jeb.biologists.org/content/37/4/845.full.pdf

    This assumption held true for decades, and at least as late as 1987 they still weren't sure. A paper that year was entitled "Why Cephalopods Are Probably Not Deaf":
    http://www.jstor.org/pss/2462006

    The above abstract notes that "hearing" versus "vibration sensing" is not a meaningful difference in water. We define "hearing" in mammals operationally; that sense conducted by the eighth cranial nerve. We don't yet know enough to do this for cephalopods.

    But we continue to learn more, and even by the time of the above article they had good clues. In 1988, they had taken the expedient of dissecting out live octopus statocysts, hooking them up to meters, and seeing if they reacted to vibrations, and could discern something about the amplitude and frequency. They did and could:
    http://jeb.biologists.org/content/134/1/451.full.pdf

    The paper describes the sensitivity of the hairs as being similar to other invertebrates (like crayfish) but nowhere near as sensitive as vertebrates such as fish. Nevertheless, they recognized that they weren't able to measure the primary nerve output, and by this time it was known that octopuses could still react to vibrations even with the statocysts removed.

    Later testing showed the greatest sensitivity for one reef-dwelling species around 600Hz, which makes sense in its environment. Another did not respond to this frequency, but responded strongly (by holding its breath for almost a minute!) at frequencies in the low bass range (50-150Hz):
    http://www.jstage.jst.go.jp/article/jmasj/34/4/34_266/_article

    Some squid species hunted with sonar don't seem to respond to those sonar frequencies, which seems a little surprising.

    Incidentally, many octopuses have reported responses at frequencies as low as 50Hz, which is the sort you'd expect to be induced by loud bass speakers. And the experiments are often done with speakers operating in the air near the tank, not directly in the tank itself. In other words, the original poster's speakers might be a problem for the animal, but it seems to me that at reasonable volumes this might not be an issue.

    Since the statocyst is moderately deep within the creature's head, surrounded by the animal's flesh, it is unsurprisingly not as sensitive as that of creatures whose hearing organs are closer to or at the surface. Also, it means that larger animals (even larger ones of the same species) might suffer from gradual hearing loss just from the ever-growing amount of tissue (mostly cartilage and muscle) between the statocysts and the surface.

    I use this assumption in my novel, but I've seen no research testing it, nor have I seen the speculation anywhere else.

    The nautilus, which has been evolutionarily separate from other cephalopods for a long time, has a slightly different statocyst design, which this paper describes (and tests some abilities of):
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692077/
     
  8. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Hearing characteristics of cephalopods: modeling and environmental impact study
    Yunfeng Zhang, Feng Shi, Jiakun Song, Xugang Zhang Shiliang Yu 2014 (subscription)

     
  9. davelin315

    davelin315 Wonderpus Registered

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    At the now defunct National Aquarium, Washington, DC, the GPO would react to a whale kiosk we had from the Aquarium of the Pacific so we had to remove it from the gallery. The calls of whales would freak it out...
     
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