Marine biologist Tierney Thys has fallen head over heels for a big, goofy fish: the Mola mola, or giant ocean sunfish. In studying the mola -- where they go, what they eat, what eats them -- she's also hunting for clues to the behavior of all life in the open ocean. With their enormous, odd bodies, peaceful habits and lust for jellyfish, these giants can be key to understanding life in the open ocean. Thys and her team are tagging and tracking molas worldwide to learn about how they live, and how climate change may be affecting all ocean life.

Thys is a National Geographic Explorer with a passion for marine education. She was also past director of research at the Sea Studios Foundation, a team of scientists and filmmakers that makes media to raise awareness of environmental issues -- including the PBS series Strange Days on Planet Earth and targeted videos that influence policymakers and businesspeople. Sea Studios was also instrumental in helping eBay stop the trading of invasive species.