Blue whales can grow to 90 feet -- that's longer than a tennis court. Getting that big requires a lot of fuel, says Jeremy Goldbogen, a postdoctoral researcher at the Cascadia Research Collective. That's why Goldbogen studies the whales' dining habits. They feed on krill, slurping in millions of the mini crustaceans along with hundreds of thousands of pounds of water in a single gulp. With the help of data tags and a National Geographic Crittercam, Goldbogen and colleagues found that blue whales do underwater acrobatics while they eat -- specifically a move they coined "the blue whale barrel roll."