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"Stones" found in excrement

Discussion in 'Tarantula Questions & Discussions' started by mothore, Feb 21, 2010.

  1. mothore

    mothore Arachnopeon

    Here's some photos of what I see



    "She" is about 2 inches. Just moulted on the 2nd (18 days ago) and hasn't eaten since. She moves around a lot, so I wouldn't presume she's hurt(?).

    I've had no luck getting details about what this is. Will somebody tell me?
  2. It's guanine. It's what tarantula's excrete and it's perfectly normal. No need to worry :)

  3. mothore

    mothore Arachnopeon

    Thank you, so much
  4. xhexdx

    xhexdx ArachnoGod Old Timer

    Great pictures of it, by the way. I can definitely see how they look like stones. :)
  5. Interesting that it's guanine. I thought guanine was mostly concentrated in the cuticle of insects, which tarantulas do not ingest. I know it's also subcutaneous in some spiders and contributes to color change (such as in crab spiders). Could you point me to a reference that shows that it is guanine and explains this concentration? (Not doubting you - but would like to see the reference for other reasons.)
  6. Bill,

    No problem :)

    In The Tarantula Keeper's Guide (2009) pg. 52-53

    "Although spiders do excrete small amounts of other nitrogenous wastes (eg. adanine, hypoxanthine, and uric acid) their principal waste product is guanine."

    From the sounds of it, they convert nitrogenous wastes into guanine, which is less toxic than ammonia. Which, I'm sure you already know.

  7. Venom

    Venom Arachnoprince Old Timer

    Is there any etymological relationship between "guanine" and "guano" ? Lol. :)
  8. Actually, according to wikipedia, guanine was first isolated in the guano of seabirds. Guano itself is derived from the Quichua language, as a word for seabirds droppings.
    So guanine is named for guano.

  9. I'm aware of that. Actually, it's one of the four building blocks of DNA. It's found in all living things. It was just the crystal form of it that was isolated (in 1859?) from the guano of seabirds. It has also been isolated from bat guano, although insectivorous bats are better producers of it than fructivore bats. Guanine has been credited with giving the shimmer to fish scales (which is where the guanine in seabird guano comes from) and is also present in concentration in insects and arachnids. I was wondering how it gets concentrated in tarantula droppings, and why it would appear in such quantities.

    Edit: I have since found a reference to the guanine in spider excrement in a book by Rainer Foelix. He goes through the process in detail, and states that the excrement contains primarily guanine, adenine, hypoxanthine and uric acid. He further says that all of these substances are nearly insoluble in water and tend to crystalize. From that I'd assume that the "stones" shown in the OP's picture are a combination of these substances blended together in somewhat crystaline form.
    Last edited: Feb 21, 2010
  10. this is a very interesting photo! thanks for sharing that. i can say i have seen that too but never so perfect. great pic!:clap:
  11. pwilson5

    pwilson5 Arachnoknight

    that is one high quality poo pic! lol
  12. Nerri1029

    Nerri1029 Chief Cook n Bottlewasher Old Timer

    Yes Bill I remembered reading it .. wasn;t sure if it was Foelix or not.

    The fact that they crystallize makes it easy for spiders to store wastes.
    If we tried to store our wastes the levels could reach toxic limits quickly as most of our wastes are soluble (as found in urine) and stay dissolved. ( talking Blood / metabolic wastes )

    So this allows the spider to be very efficient especially in extracting the water from the waste as well.