The first few moments MJ was in the water, he hesitated before sticking his head out. But it didn’t take long for him to explore the new environment and accept his home.

For the past two years, MJ has been the Museum of Discovery and Science’s sea turtle ambassador, helping to educate 1 million visitors about conservation.

But on Wednesday, the loggerhead was loaded into a truck in Fort Lauderdale and driven north to the Indian River Lagoon near the Sebastian Inlet, where he was released back into nature.

“It’s like letting your children go off to college,” said Marlene Janetos, the museum’s vice president of marketing.

MJ — named after Mike Jackson, AutoNation chairman and CEO, who was awarded the museum’s 2010 community leadership award — was rescued from Juno Beach in 2010. At the time, he weighed 42 grams and had a shell length of 4.8 centimeters.

Every year some hatchlings get stranded because of problems like lightning storms.

The Florida Fish and Wildlife Conservation Commission requires that loggerhead sea turtles be 45 centimeters before they can be set free.

Museum aquarist Brett Cardinal and Matthew Dumler, the museum’s life sciences manager, have taken care of MJ for the past two years, monitoring his diet and maintaining a clean environment.

Although MJ had a healthy diet of live crabs, shrimp and squid, some days he wouldn’t eat at all; other days he ate non-stop.

Weighing in Wednesday at 42 pounds and measuring 51 centimeters, MJ has a bit of a buffer in case he doesn’t eat the first few days, Cardinal said.

“Sea turtle populations worldwide, most of them are endangered. Florida is considered threatened,’’ Cardinal said. “It’s always good to release them back. Hopefully it’ll bring the population back up one day.”

As he was pulled out of his tank, MJ flapped furiously with bursts of energy.

The spikes along MJ’s brown shell can be an indication of how aggressive he is.

“He tries to bite you and stuff if you get close to him,’’ Dumler said. “He’s definitely not synthesized to humans. He’s aggressive, but he’ll be all right.’’

Dumler wasn’t sure MJ would be able to return to his natural environment when he contracted a virus earlier this year, but he quickly recovered.

“After today, it’s sad to see him go, but we’re happy to see him go and be out in the nature,’’ Dumler said. “It’s important to show everybody these animals exist.’’

Although the museum lost its ambassador, it wasn’t without one for long.

Wednesday afternoon, another dark brown loggerhead arrived. The baby turtle was rescued from Juno Beach.

The museum hasn’t named it yet, because it is too young to know if it is a male or female.