Mr. Ray is the teacher of Nemo's class. He's the jolliest science master working in marine education. He is an eagle ray who believes in the practical, taking his little fishy pupils for a ride on his back to teach them about the other creatures of the seabed and singing a whole bunch of memory-aiding ditties along the way. He helps teach his class by singing the "Let's Name the Species" song. He is very protective of his students, telling them to hide under him when danger approaches. He takes the class on a field trip to the drop-off, much to Marlin's discomfort for his son's sake. In the end, he is seen with a newcomer student named Squirt who joins the whole class on another field trip.
Mr. Ray first appears telling his class about the Stingray migration, a journey back to home. When the Stingray show up, Dory, who was staring at the seaweed thinking about her past, accidentally gets swooped up by the Stingray swarm, knocking her out. He is last seen wishing Dory good luck on finding her parents. At the end, it is revealed Mr. Ray left his class under Hank, Destiny, and Bailey while he joined the migration.
- A toy alluding to Mr. Ray appears in Toy Story 3 twice.
- Mr. Ray appeared at the beginning of the introductory video at The Science Behind Pixar along with Roz from Monsters, Inc. to greet the visitors and provide them with safety precautions.
- Mr Ray: "Welcome aboard, explorers! Mr. Ray here, your science teacher for the day. Let's get this show started! I want all optical orbits up front, and remember, we keep our supraesophageal ganglion to ourselves. That means you, Jimmy!"
Roz: "And hello, it's me, Roz. You monsters make sure that your tentacles and horns are not blocking anyone's view. And no food or drinks in the exhibit. Let's get started."
- —Mr. Ray and Roz at the beginning of The Science Behind Pixar introductory video.