RE: salt water needs

From: pulipal@netscape.net
Date: Tue Apr 15 2003 - 11:47:07 EDT

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    Question:

    I was curious why marine mammals (pinnipeds and cetaceans) need salt water.
    I know that in the wild they feed on fish that live there, but why do they
    need to be in salt water in aquariums?

    kkilgus@mysticaquarium.org
    *************
    Answer:

    Hi, Kelly. I actually passed your question on to a former Mystic Aquarium employee (Rob Nawojchik) who now works at the same place I do. He says that cetaceans need to be kept in salt water in aquariums because of their skin. When kept in fresh water, the skin of cetaceans will slough off. This is probably an osmotic reaction of the salt-water-adapted skin. Interestingly, beluga whales (most notably the Hudson Bay population) migrate into fresh water rivers each year to molt their skin.
     
    As an aside, all mammals need to drink fresh water. Cetaceans (like other mammals) can not drink the salt water within which they swim. So ... they get their fresh water as a break-down product from consuming fish.

    Hope this helps,
    Dagmar Fertl

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