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How many senses? which animals can see in colour?

  1. Jan 21, 2004 #1

    Nereid

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    Humans have colour vision - we have rods (which are quite sensitive to light) and cones (which come in three types, and whose different responses to light of different wavelengths our brains interpret as 'blue', 'green', and 'red').

    Do any other mammals have colour vision? If there are any, do they use the same mechanism (cones)?

    Do any other animals have colour vision? If so, what mechanisms do they use?

    Human eyes (and brains) can 'see' light with wavelengths from ~395 nm to ~700 nm. IIRC, some animals can 'see' UV (shorter than 395 nm) and some others IR (longer than 700 nm). What are the extremes? How do the receptors differ from our rods and cones?

    Humans also have a sense of touch, smell, taste, and hearing. IIRC, some snakes have a sense of 'heat' - it's not 'sight' because there's no imaging done with the IR their pits detect. Other animals - the platypus, some eels? - have a sense of 'electrical field strength' in water. A magnetic field direction has also been reported (IIRC) in some birds (and bacteria?).

    The senses of smell and taste are 'just' presence/absence (and strength) of certain chemicals, and this is common in living things.
     
  2. jcsd
  3. Jan 23, 2004 #2

    Dogs, contrary to popular belief, can recognize colors.

    Fish are believed to be able to recognize colors.

    Color vision may be the norm in the animal kingdom.
     
  4. Jan 24, 2004 #3

    Nereid

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    references?

    Would you post some references please?
     
  5. Jan 24, 2004 #4

    LURCH

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    Re: references?

    Here's one that I found. It says that dogs can see some colors, but are red-green colorblind.

    Also, the ability to perceive color is believed to be very prevelant among birds.

    Nocturnal animals have a reflector in the back of their retina called a tapetum, which reflects light that missed the receptors on the way in, giving it a chance to be detected on the way back out, tremendously amplifying night vision.

    Here is another link with a lot of interesting data.

    Electrical field detection is known as "electroreception" and is, AFAIK, only present in sharks and rays. This sense is performed by "Lorenzini receptors" (which I probably misspelled). I have actually seen film of hammerhead sharks (my favorite shark) sweepimg the ocean floor with their snout just above the sand. Using the Lorenzinies in their snouts like a metal detector, these animals found prey burried under the sand. They would just stop suddenly and take a big chomp out of the seafloor, and a skate or flounder would appear from the cloud of muck!

    I also have seen that squid and octupy, although they can change color better than any other creature, cannot see it.
     
  6. Jan 24, 2004 #5

    Nereid

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  7. Jan 25, 2004 #6

    LURCH

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    Very cool! They seem to have active, rather than passive radar.

    BTW, did you know they're also poisonous?
     
  8. Feb 8, 2004 #7
    I was just wondering how exactly do they determine the color vision of other animals. Obviously they must have some form of test(s), but without verbal communication how can they know for sure. Even the most highly trained animal still could unable to comprehend something like this.

    Although, I wonder, would it be possible to actually see colour strictly by wavelength. Assuming you were technically colour blind, but could discern differences in wavelength and could determine colour based on shades. And if so, would you still be considered colour blind if you could do this?
     
  9. Feb 9, 2004 #8

    Phobos

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    Off the top of my head from watching science documentaries & reading books (perhaps later I can dig up some links)...

    cats have partial color vision (difficulty seeing red? I forget)

    so do bees

    some flower-loving insects (like bees) can see further past violet than we can

    I'd have to assume that the great apes can see color to some extent given their relation to us.

    I agree...particularly considering the colors they display (so I would tend to think birds fall into that category too). Same goes for squid & octopus since they can change colors like a chameleon(sometimes used for communication I think).
     
  10. Feb 9, 2004 #9

    LURCH

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    Tests in animals are done by reward for recognising diferent colors. These tests are not fool-proof, but pretty convincing IMHO. In order to get a false result, the animal would have to ahve some ulterior motive. It would have to refrain from agtting its reward for the purpose of deceiving the lab-tech into thinking it couldn't see color. And this would have to be a conspiracy agreed upon by all the thousands of individuals within a species that get tested. Not impossible, but highly improbable.

    No, the ability to recognise wavelength is all that color vission is, so recognising wavelengths is seeing color.

    But the animal testing above did lead to some misleading results in the early years due to the animals' ability to discern between amplitudes or brightness. Once researchers detected this flaw in the testing method, much re-testing had to be done. Colored test objects had to be carefully selected to have equal brightness, at which point many animals lost their ability to see color.

    I once saw a test of an octopus, placed in a fishtank with colored gravel on the bottom. one half of the tank had red and blue gravel layed out in a pattern of large blocks. The octopus changed its color pattern to a set of blocky geometric shapes. A partition in the middle of the tank was raised, and the octopus was free to mave to the other half, where the bottom was colored in similar large blocks of yellow and green. But these particular shades of yelow and green were selected bacause they were of equal brightness. The octopus became a single uniform sheet of grey.
     
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