MELBOURNE, FL (FloridaToday) -- The gray dorsal fin briefly popped above the ocean surface near Melissa Sanhueza in chest-deep water near The Tides Collocated Club.
Then the fin disappeared -- and the shark sank its jaws into the left heel of her 9-year-old son, Christian, who was boogieboarding just a few feet away.
And the boy vanished beneath the waves.
"It happened fast. As soon as he went under, he shot right back up, screaming, 'Mommy! A shark bit my foot!'" Melissa recalled.
"I grabbed him and ran," she said.
The Orlando rising third-grader suffered a severed Achilles' tendon and ligament damage in the Saturday afternoon shark attack off Patrick Air Force Base. He has undergone two surgeries at Holmes Regional Medical Center in Melbourne.
Tuesday morning – on Christian's ninth birthday -- Health First media handlers invited television photographers and reporters to his eighth-floor room in the pediatric wing. Balloons tied to his bed read "Get Well Soon" and "Happy Birthday."
His left leg was propped on a pillow, bandaged with white gauze from mid-calf to toe.
Christian shared space on his hospital bed with an Iron Man stuffed doll, a Spiderman action figure and an Avengers sticker book. He mingled with relatives and greeted Oreo, a red-vested black Labrador therapy dog.
"If I would see a shark, I would throw it in the trash," Christian vowed, coloring a dinosaur book with a marker.
Days before his ninth birthday, Christian Sanhueza was bit by a shark while swimming off the coast of Florida.
Despite his injuries, Melissa said her son has remained in good spirits. In second grade, he did a school project on megalodons, the extinct prehistoric mega-sharks.
"He doesn't want anything to do with sharks now," she said.
Christian could be discharged Friday, and he faces future surgeries at Arnold Palmer Hospital for Children, Melissa said.
"He's an amazing kid. Considering what just happened to him, he was very calm and brave. And I'm proud of him," she said.
She estimated the shark measured 3 feet long. Christian and Melissa were visiting the PAFB beach during a family day trip to celebrate his birthday with his father, Reinaldo, and sister Faith, 8.
"The ocean, we're going into their territory. So we just have to be more aware of our surroundings," Melissa said. "Because we're out there to have fun, and we forget that there's things in the water."
PHOTOS: Shark Pictures