It takes a warm-blooded naturalist to run a den of cold-blooded creatures. Gus and Shane Ben David’s World of Reptiles is now in its third year. These are the animals that will never be friendly, but they do get along. They range in size from a 21-foot, 230-pound reticulated python down to a bullfrog from Cape Cod.

Like a chameleon, there are many colors to Gus Ben David. For 28 years he has been the director of the Felix Neck Wildlife Sanctuary on the shore of Sengekontacket Pond, a place he helped create. He wears a khaki shirt with a blue lapel button that carries the words Massachusetts Audubon director.

But at night and on weekends, he becomes the manager of a home for descendants of dinosaurs. With all the snakes, alligator, turtles and lizards under his care, he runs the leading reptile exhibition center in the state. There is not another place like it and he does it from home, down a dirt road from the Vineyard Haven-Edgartown Road, not far from the Audubon sanctuary.

The World of Reptiles is the continuation of a dream that Mr. Ben David had as a child. In the basement of his home, on the wall there hangs a poster dated 1967. It reads: “Visit Gus ’n’ Gus Wildlife Farm, birds, mammals and reptiles on display 25 cents.” He was 24 years old when the poster was made. His uncle was a partner.

In 1969, Mr. Ben David was diverted from his interest with the creation of the 350-acre Felix Neck Wildlife Sanctuary by a group of friends that included the late George Moffett and Anne Hale. “We took open land and created a wildlife sanctuary from scratch.”

Three years ago he took his new home and converted the basement. The creatures are stored behind glass in pinewood display cases. For the benefit of the animals, the temperature of the room is kept warm in all seasons. Schoolchildren of all ages and their parents routinely come to the center to touch these exotic creatures. “This has been a dream on hold for a lot of years. I’ve always had this plan to work with animals. I wanted to start my own zoo.”

Mr. Ben David has the four largest species of snakes. He has two green anacondas from South America, the largest measuring 13 feet in length. “She is just a baby,” he said. He has a 14-foot African rock python and three Burmese pythons from India. And there is an odd looking white snake.

“I have the largest albino specimen in captivity anywhere in the world and she measures 16 feet,” he said.

Add to that a 10-foot boa constrictor.

Four years ago the New York Zoological Society, formerly the Bronx Zoo, gave Mr. Ben David one of the rarer snakes to have been kept in captivity, a seven foot long Texas Indigo. The black snake has a slight tinge of blue, which is how it gets its name.

His newest arrival is an 18 inch long American alligator that is about a year old. The animal has free run of the exhibition area and saunters across the green-painted concrete floor as if it owns the place.

Similar to this small creature, there is a much larger five foot Caiman, a relative to the alligator. The seven year old creature has “spectacle” eyes. Its stare can cut glass.

Of most of these creatures, Mr. Ben David said: “You can never trust them.”

There is a large Savannah monitor lizard with “a face only a mother could love.” It looks like a miniature version of the prehistoric Tyrannosaurus rex. It has a long, searching tongue.

There is only one reptilian creature with a human name. Big Al is a snapping turtle Mr. Ben David has kept for 12 years. It takes two hands to lift the 50 pounder, one of four native species of reptiles. “It is named after a living Islander,” Mr. Ben David said, Albert (Big Al) Fischer of Gay Head.

All the reptiles, except for the native animals, were bred in captivity. Mr. Ben David has secured special permits to use these animals for educational purposes. It complements his work at the Audubon sanctuary. Over the years he has brought rare and interesting animals into the school. Hundreds of youngsters have seen the golden eagle Chameli, which he keeps in a pen in the backyard of his house. “I’ve had her for 18 years,” he said.

The most recent acquisition is an African bullfrog that now is about the size of a softball. When it first arrived in Edgartown the creature was a tadpole not bigger than a 50 cent piece.

Mr. Ben David has his thoughts on the future. He’d like to see his living museum get bigger and busier. For now, his avocation remains a part-time job. And when the time is right for him to step down as director at the sanctuary, he will devote more of his time to the creatures in the basement of his home.

Starting on the Fourth of July weekend, the World of Reptiles shifts into a summer schedule of being open on weekends from 10 a.m. to 3 p.m. For now it is only open on Sundays.

Across Massachusetts there are many places you can see reptiles. There is the Worcester Science Center, Roger Williams Park in Providence and Massachusetts Audubon Trailside Museum. But none of them have as great a variety of snakes as Mr. Ben David’s World of Reptiles.