If you’re heading to theaters this weekend to see the much anticipated “Finding Dory,” take note of how Mr. Ray glides effortlessly through the water, and grouchy Hank the octopus curls and lifts his tentacles.

It’s no accident these motions look realistic—the animation company Pixar sought expert advice from University of Washington fish biomechanist Adam Summers for its second movie about life under the sea.

Summers, a UW professor of biology and aquatic and fishery sciences who is based at Friday Harbor Laboratories, advised Pixar on ichthyology for the company’s 2003 hit “Finding Nemo.” He did it again for the long-awaited sequel, answering questions about how certain animals swim and move around in the water.

Summers talks about both advising experiences—including the tension between entertainment and science, being corrected by kids, and the drama of the piscine world—in a Q&A appearing June 15 in Nature. The journal’s editors also discuss Summers’ work in an editorial arguing that if ocean life is to be preserved, more people must get to know the wonders of the marine world.