When Carl S. Perkins dives in to feed the fish and sharks at the National Aquarium in Baltimore's Inner Harbor, he employs a little marine psychology.
"It's sort of like directing a symphony with all the musicians playing on the podium with you," said Mr. Perkins, an assistant principal at Oakland Mills Middle School and a 13-year volunteer diver at the aquarium. "You know which ones are going to nip at you and which ones are really shy and you have to hunt them down to feed."
Once a month, Mr. Perkins dons his blue wet suit and gear to hand-feed the marine life.
The 43-year-old educator knows what to do when hunger strikes the aquarium's 160-pound hawksbill turtle.
He and other divers have nicknamed the turtle "Pita," an acronym, he says, for "pain in the ankle."
"I say that for a lack of a better word," Mr. Perkins said. "He's very much of a pest. He nudges you and gets all over you. He's just very obnoxious. He continues to come at you and crash into your head, these types of things, till you feed it. Then it will go away."
Mr. Perkins said that even the aquarium's biggest tank, its 335,000-gallon Atlantic Coral Reef exhibit, can seem crowded at times.
Divers have to take care not to bump into their charges.
"If anyone is going to get claustrophobic, that's where it will happen. It's really tight in there," he said. "I'm 6-3. It really creates a problem."
But his time as a volunteer diver at the aquarium -- feeding tropical fish, sharks and rays, cleaning the tanks and giving public presentations -- has given him confidence when he's surrounded by marine life.
"If you never did that before . . . it's an eerie feeling at first. But once you become used to it, then you know what to expect," he said.
Divers feed the aquarium's residents smelt, clams, shrimp and squid plus pigments and vitamins put into gel form to help them keep their color in captivity. And occasionally, they'll also get medicine, Mr. Perkins said.
When the aquarium stocked them, barracuda were Mr. Perkins' favorites. "They are in such control of their environment. . . . They are masterful swimmers," he said. "You're in their territory and they know it. It's evident."
In the water, Mr. Perkins said, he's unafraid of the marine life. He's afraid of something else: "My biggest fear's doing something silly in the tank by accident" in front of the visitors.
His daughter and his students have been among the aquarium's visitors.
"Many of them didn't know I was involved in the program," he said. "They didn't know till they saw me on the other side of the glass."
Mr. Perkins' love for marine life can be traced to Lloyd Bridges' late 1950s television show "Sea Hunt," which fascinated him as a child.
"I never missed that show," he recalled. "Until I was an adult, I thought it was something for other people. Not me."
When he got older he asked himself why he couldn't do something similar. "I didn't have a good enough answer why not," he said. In 1977, he became certified in diving.
About that time, a cousin began work at the new aquarium. When the aquarium's diving program began in 1981, he told Mr. Perkins, who was accepted a year later.
Mr. Perkins makes little of being just one of two black divers among the 97 volunteer divers at the aquarium, which attracts 1.5 million visitors annually. Curtis Ellis, a media specialist at Morgan State University, is the other.
"I do a lot of things where I'm in the minority," he said. "So it's nothing new."
Hundreds of black divers across the nation go unnoticed, he said. "I feel I'm a role model, not just for African-American kids, but for all kids," Mr. Perkins said.
Mr. Perkins is a good, reliable diver, said Alan Henningsen, the aquarium's volunteer diver coordinator.
To compete for a spot in the volunteer diver program, applicants must pass a written test covering diver physics, biology and safety. The top scorers are invited back for an in-water test.
"The reason I got into it in the first place is because I have a strong desire to dive in the ocean and act as a volunteer," Mr. Perkins said. "Here's an opportunity to satisfy both sides of the coin."