On May 17 I wrote about two fin whales approaching my sailboat, noting that I could smell their nose-wrinkling breath after a blow. I wrote, "The odor isn't what you'd call refreshing. It's the essence of dead fish."

That day, a Big Island boat captain and marine naturalist e-mailed me that "whale breath ... does sometimes smell, but it's not because you're smelling dead or decomposing fish from their dinner. ... Whales with bad breath actually have a form of diphtheria."

The captain thoughtfully included the source of this information, a website called WhaleNet, sponsored by Boston's Wheelock College, specializing in early childhood education.

In 1994 a Boston-area dentist, Tom Ford, posted on WhaleNet his theory that the lousy breath in humpback whales does not come from the food they eat, but rather from bacteria in their respiratory tract. He based this premise on the fact that a whale's respiratory system has no connection to its digestive system, as it does in humans. Therefore, Ford reasoned, the foul odor on a whale's breath can't come from its food.

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