From a beach near his home in North Haven, Dan Rizzie is wading in Shelter Island Sound and feeling mostly unafraid—even with little sharks swimming around his feet.He has heard the stories of irresponsible or simply unlucky swimmers and seen the infamous 1975 blockbuster “Jaws.”

The baby boomer once bought into the hype—but no longer.

“You just assume that if there’s a shark in the water, it’s going to kill you, when, in fact, they don’t want to mess with you at all,” Mr. Rizzie explained. “But you’ve got to remember that you’re in their territory.”

Beautifully designed, extremely efficient and spread out all over the world, sharks are the ultimate predators. There are hundreds of species, ranging from the 9-inch-long pale catshark to the whale shark, the largest predatory fish in the world, measuring in at 55 feet, with a mouth the size of a Volkswagen that could swallow a sofa, though they prefer to filter feed.

As a whole, sharks are perhaps the most misunderstood creatures on this planet, according to marine biologist and artist Richard Ellis, whose illustrations will be on view starting Friday—alongside work by Mr. Rizzie, April Gornik, Donald Sultan and more—at the Sag Harbor Whaling and Historical Museum.

“The whale shark looks like a shark, but it’s harmless,” Mr. Ellis said during a telephone interview from his home in Manhattan. “What is responsible for their bad reputation is the occasional shark attack by certain sharks on people. So if there is a creature that gets to be 30 feet long that has gigantic teeth and feeds on things like seals and whales, it becomes fairly obvious—though not necessarily true—that they do terrible things to human beings if they find themselves in the water with one of these babies.”

Mr. Ellis, a lifelong New Yorker, grew up a stone’s throw away from the Atlantic Ocean—its waves, its smells, its sounds and its marine life—on the Rockaway Peninsula in Belle Harbor, Queens. He was fearless and endlessly captivated by “all things that came from the water,” he said, “because I became fairly close to being one of them.”

With a degree in American civilization from the University of Pennsylvania, he marched into the Museum of Natural History in 1969 and asked for a job as an exhibition designer, with no credentials other than curiosity, determination and a habit of obsessively doodling wild animals and sea life, something that started when he was a child.

“I would be sitting in class, learning about the Revolutionary War—except I was drawing swordfish,” he said. “I didn’t think this was going to mark the beginning of my career, but it did.”

Remarkably, he was hired and tasked with designing the museum’s Hall of Ocean Life—in particular, its centerpiece for which Mr. Ellis would become known: a 94-foot-long life-sized blue whale suspended from the ceiling to this day.

“Overnight, I learned about the biology of fishes. And there I was, behaving like an expert,” he said. “I sounded like I knew everything in the world about the biology of fishes. I didn’t really. I faked it.”

He hesitated, and corrected himself. “I didn’t so much fake it. I remained one step ahead of them.” He watched countless films, frequented museums and aquariums, and engulfed himself in nature—logging thousands of hours underwater, watching his subjects up close through his scuba mask.

And, all the while, he painted what he saw.

The testimony to that tenacity, drive and productivity hangs on one of Mr. Ellis’s walls—the jackets of his 22 published books, which he illustrated, the first being “The Book of Sharks” in 1975. Ironically, it sought to dispel misinformation about sharks the same year “Jaws” lit up the silver screen.

Before the film’s aftermath came to pass, Mr. Ellis received an unexpected call the year before.

“Hello, I’m Peter Benchley, and I understand you’re painting pictures of sharks.”

“Yes, I am,” the artist replied.

“Would you mind if I came to look at some of them?”

The painting Mr. Benchley bought would ultimately become the cover of “The Book of Sharks,” explained Mr. Ellis, who at the time, had no idea the man standing in his living room was the author of “Jaws,” the novel.

“I hadn’t sold a shark picture ever, and I didn’t know I was going to,” Mr. Ellis said. “Because it was Peter, it launched me on a career as a shark painter. It had never occurred to me there was such a thing as a shark painter—or that I would become one.”

The sale sparked a longtime friendship. They fished together in Montauk, where they were easily recognized as shark authorities. They would come back with the wildest of tall tales. “We saw these giant white sharks!” they’d say. “They were 75 feet long. One of them ate the boat whole!”

They enjoyed the fun they had, but the ramifications of Mr. Benchley’s novel were not lost on them.

“We became very, very close friends. Benchley, he regretted what he had done, though he didn’t know it was coming,” Mr. Ellis said of the late author. “There developed an entire industry based on the fear of sharks. Sharks had acquired a reputation of being maneaters—which rarely happened, but often enough to add to that reputation.”

The attacks paired logically with the kill tournaments held around the world—“where guys get drunk and catch as many sharks as possible, and just butcher them,” Mr. Rizzie said.

“It’s atrocious. Reprehensible, horrible,” he continued. “I’m not such a seasoned swimmer that I’m not always apprehensive or aware. If I was bobbing around in the surf and a big, black fin came breezing past me, believe me, I’d probably walk on water. I don’t profess to be completely comfortable or understand them. But I’ll tell you one thing: I have a great deal of respect for them.”

About three years ago, Mr. Rizzie caught a 400-pound nurse shark down in the Bahamas. He pulled it onto the boat and held it while his friend removed the hook from the creature’s mouth.

And for just a moment after they released it back into the water, the shark paused, almost as if to say, “Thanks,” before it swam off.

“Shark! The Misunderstood Fish,” featuring work by Richard Ellis, April Gornik, Dan Rizzie, Donald Sultan and more, will be on view from Friday, July 3, through Wednesday, July 29, at the Sag Harbor Whaling and Historical Museum. The exhibit will open with a reception on Friday, July 10, at 6 p.m., followed by a 40th anniversary screening of “Jaws.” The weekend’s festivities will continue on Saturday, July 11, with a screening of “Pirates of the Caribbean” and a family picnic, and on Sunday, July 12, with a lecture by Mr. Ellis from 10 a.m. to noon. For a complete list of events, call (631) 725-0700, or visit sagharborwhalingmuseum.org.