It doesn't involve a captain of any sort, but I am reminded of the following story by all the accounts of poisonous vs venomous:
A friend of mine was in the Army, and was somewhere in Asia in a remote location, when he was stung by a scorpion. His men quickly radioed in to the nearest hospital, and the doctor inquired whether it were a black or a red scorpion. So there he is, lying there, waiting while his men are literally beating the bushes, trying to find the scorpion.
Then, he hears a voice from the radio: Is Major Ross still alive?
Someone replies affirmatively, and the doctor says, 'Then I know what kind of scorpion it was.'
Gee, thanks, doc.
Although I suppose it wouldn't have been useful for him to say, 'Well, with one color, you'll be dead in 5 minutes, with the other, you're going to survive.'