The young boy whose arm was ripped off in a shark attack began to breathe completely on his own late Thursday after being weaned off of a ventilator, although doctors say his condition remains critical.

Earlier Thursday, doctors said 8-year-old Jessie Arbogast moved his surgically reattached arm and opened his eyes.

The boy was in a coma-like state and threatened with brain damage after losing most of his blood during the attack Friday. He lay in critical but stable condition at Sacred Heart Children's Hospital in Florida.

"I moved his right arm, the one that was replanted," said Dr. Juliet De Campos, an orthopedic surgeon who helped reattach the arm. "It was next to his body and I moved it away from his body to let his armpit breathe a little bit, and he immediately moved it back down."

"Technically he's unconscious because he's not conversing like you and I are conversing, but he is showing very promising signs of starting to arouse somewhat," De Campos said.

Doctors had not used the term coma until Tuesday, when tests showed brain activity akin to deep sleep or a light coma.

De Campos said another doctor who examined Jessie earlier Wednesday reported that Jessie responded when the physician rubbed the boy's chest and called out his name.

"Jessie opened his eyes and Jessie looked at him, and he also moved his right foot and his left arm," De Campos said.

Doctors released a statement Wednesday night saying the boy had also wiggled his toes when asked to do so. The statement did not provide any further detail.

A 7-foot bull shark attacked the Ocean Springs, Miss., boy while he was wading in knee-deep water on a Florida Panhandle beach Friday.

Jessie's uncle wrestled the shark to shore after the attack and a ranger shot the shark four times with a 9 mm pistol. After the ranger pried the shark's jaw open with a police baton, a volunteer firefighter used a clamp to pull the boy's severed arm out of its gullet.

The boy had no pulse and no blood pressure when he was airlifted to Baptist Hospital about 30 minutes after the attack.

The boy also suffered a severe leg wound. The loss of nearly all his blood harmed virtually every organ in his body.

The Associated Press contributed to this report.