Killer whale, digestion miscellaneous

From: pulipal@netscape.net
Date: Wed Sep 18 2002 - 10:29:36 EDT

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    This question is about Orca digestion. I have read that the Orca can
    swallow a seal whole that it can have one or more whole seals in its
    fore-stomach, and that the whale does not chew the seal. I have read that
    Killer Whales have several stomachs, and that the fore-stomach does not
    secrete digestive enzymes.I have also read that the opening from the
    fore-stomach to the next stomach is very small (a few cm.).
    My question is, how does the seal get from the fore-stomach to the stomachs where the digestion takes place? How do the bones get through, if they have not been exposed to stomach acid? My guess is that the opening into the second stomach is actually more expandable in life than was previously
    thought, but I'd like to know what the real story is.

    I have seen a suggestion that the seal is mostly or completely
    auto-digested by its own enzymes and bacteria while in the whale's
    fore-stomach, and that this is how it gets through the tiny opening. Does
    this happen to any significant extent, or is it a myth?
    *********************************************************
    Wow, this one was a stumper, especially since I'm not a hard-core killer whale scientist or anatomy person. I asked two people very familiar with killer whale feeding behavior. One person is not reachable until after this coming weekend (I'm not sure when you need your answer by, but I can provide the additional information when I get).

    The other expert says:
    1) I doubt if a KW could swallow an adult seal whole. Generally, killer whales do not swallow marine mammal prey whole, but tear off small pieces. They do not chew their food, as all their teeth are pointed (no molars).
    2) Yes, they have several stomachs, like cattle. The forestomach is for softening food, and I believe that it does not secrete digestive juices.
    3) The idea that seals are auto-digested in a killer whale stomach sounds like a myth to me. But, I am not sureā€¦

    As I said, I will provide you any additional information as I receive it.
    Interesting question.

    Dagmar

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