Charleston Southern University science professors Jim Barrier and Steve Best love life, teaching, the natural world and fishing.

The men are deeply respected by generations of students and have taught, by their own count, more than 20,000 students in their combined 77 years at the university. They know how to make complex material understandable, and they'll work with students until they master it, former students said.

And Barrier and Best, who are best friends and will retire at the end of the semester, are really funny.

Joseph Russell, a former student of Barrier and Best's -- the men are rarely referred to individually -- is now a medical student at the University of South Carolina. Russell took courses from and worked as a lab assistant for both professors when he was an undergraduate student at Charleston Southern. They helped him prepare to apply to medical school, he said.

Best, who teaches zoology and mammalogy, has a cart of animal specimens that he occasionally holds up during demonstrations, including a stuffed dove with a head that wasn't properly attached. Sometimes, to shake up a class, Best lets the dove's head fall off during a lecture, Russell said. Students always gasp at first, before they realize it's a joke. Then they break out in laughter.

And Barrier, who teaches botany and ecology, and Best are avid fishermen, Russell said. They have foot-operated trolling motors on their boats and fish with a rod in each hand.

One day Barrier, who often brings his boat to the North Charleston school hoping to be able to break away and fish at the end of the day, invited Russell and his roommate to go fishing with him. He challenged them to see who could catch the most fish; Barrier would compete against the two students combined. Barrier maneuvered the boat around the lake with his feet and reeled in many fish with his two rods, Russell said. He and his roommate combined brought in only three.

Russell enrolled in Barrier and Best's classes on the recommendation of his father, Roger Russell, a 1983 Charleston Southern graduate and a local physician.

"Being taught by professors Barrier and Best was the ultimate learning experience," Roger Russell said. There were no empty lectures. They challenged students, he said. His daughter Valerie is currently an undergraduate student at the university and also has taken courses from the two professors.

"They were enthusiastic about the subjects they taught and were genuinely likable individuals," Roger Russell said.

Barrier and Best first met when they were both graduate teaching assistants at Clemson University. Barrier came to Charleston Southern in 1970, Best in 1973.

Best said when he first arrived on campus, there were about 30 biology majors. Today, there are about 200. He and Barrier encourage younger students who show an interest in biology to pursue it as a major.

Both men said they love nature and the outdoors, and they never tire of trying to convey that to students. Many academic institutions focus on research, they said. They both simply love to teach.

"We're energized by the students," Best said, "and we try to deliver in the classroom."

Sam Gandy, who graduated from Charleston Southern in 1976 and went on to earn a medical degree and a doctorate in molecular cell biology, is now an expert on Alzheimer's disease and works as a researcher at Mount Sinai School of Medicine in New York. When he was at Charleston Southern, he took courses of Barrier and Best's.

Gandy knows how challenging it can be to explain complex science to people who are not trained scientists, and he appreciated Barrier and Best's skills in that area. Both men, he said, "were gifted in explaining complex concepts in comprehensible language."

Barrier and Best, who had an "open-door policy," which to them meant anyone could stop by anytime and talk about anything, said they are now ready to retire. Barrier thought about retiring before the school's new science building opened in 2005, but Best talked him out of it.

Both men are married to educators and have grown children. They both have done some traveling, such as a trip with their wives to Thailand in 2007 to study wildlife ecology and the Asian elephant. A trip to Tanzania is in the planning stages.

And they will continue to go fishing as often as they can.

Barrier already has taken down the two stuffed largemouth bass from his office walls. One of them weighed in at 10 pounds, 13 ounces and was the largest he has ever caught.

Roger Russell said "their shoes are quite large and they're going to be hard to fill."

His son Joseph said, "if they would just hang around another 20 years, I would send my kids to them."