When Dwayne LaGrou asked Weird Animal Question of the Week what animals have the largest eyes for their body size, we were sure the answer would be guilty-looking dogs.

The actual candidates proved to be some real eye-openers.

Because animals are built so differently, figuring out which has the biggest eyes can be tricky, Sönke Johnsen, a biologist at Duke University, says via email. (Read more about eyes, nature's most exquisite creation, in National Geographic magazine.)

But some tiny marine animals, such as some hyperiid amphipods, clearly come out ahead.

These include Cystisoma, a genus of transparent crustaceans whose giant compound eyes face upward on a head that takes up about a third of its seven-inch (about 18-centimeter) long