Sea Birds and Seawater

Correct Answer: C. Salt glands secrete the excess salt.

This is a great DAT comprehension question. Let’s run through the answer choices and see what we can eliminate. Choice [A] is wrong because there is no structure in the intestine that can physically eliminate salt. Choice [B] is wrong because most chordates have similar osmolarities. Choice [D] is incorrect because nephrons become longer to resorb MORE ions and water, not less. A classic example are rodents in the desert that have very long loops of Henle to resorb as much water and ions as possible. Lastly, specialized bacteria will still eliminate the salts after they’ve used them, so it does not solve the problem of excessive salt. Choice [C] is correct, sea birds have supraorbital glands, or salt glands, above their eyes, which secrete excess salt from their blood. It functions similar to a kidney, but is much more efficient at excreting salt.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.