LOS ANGELES >> The conventional wisdom is that public sympathy is evoked by seeing one person in need of help, not the many.

Photographer Joel Sartore has staked a decade of his life, and counting, that the same holds true for animals and the imperiled wonder they represent.

As detailed in PBS’ “Rare: Creatures of the Photo Ark,” Sartore is on a quest to capture images of the roughly 12,000 species in captivity around the world, including rare and endangered ones, to persuade us they are worth protecting. The three-part series debuts Tuesday (check local listings) on PBS stations and online.

Sartore’s subjects, ranging from majestic elephants to comical insects, are placed against an elegantly spare black or white background. There is an unsettling challenge in the gaze of mammals, or so Sartore’s artistic lens makes it seem.

“The animals are the poetry. They’re beautiful works of art,” Sartore said in an interview. “They do all the talking. My job is to get out of the way.”

But if his images of beauty and vulnerability fail to sway people, he said, maybe self-interest will.

“We really want to get people in the tent of conservation, and make them realize you can’t lose half of all species and not have it come back and affect humanity in a very detrimental way,” Sartore said.

In his quest to build a virtual ark that captures the world’s biodiversity, the National Geographic fellow has visited nearly 40 countries to make digital images of more than 6,000 species that include, roughly, 900 mammals, 600 amphibians, 1,800 birds, 700 fish and 1,200 reptiles.

He works with zoos, wildlife habitats, aquariums and other facilities caring for animals, although he ventures into the wild when needed. He and Chun-Wei Yi, the PBS series’ director and producer, focused on rare species, including New Zealand’s kakapo, a flightless bird, and the Yangtze giant softshell turtle in China. The latter has dwindled to three ancient survivors, Sartore said, with one rescued from being sold for meat decades ago by a circus owner impressed with her size.

“We hope audiences find it an important story that we’re looking to tell in ways that are beautiful, heartfelt, and often funny,” said John Bredar, programming executive at series producer WGBH Boston. National Geographic is presenting exhibits at major zoos nationwide as a complement to the series, he said.

Sartore’s appreciation of the wild was nurtured by his parents during his Nebraska youth, in which he hunted and fished with his father and shared his mother’s love of nature. A book she owned on birds included a chapter on extinct species, including the passenger pigeon that once filled America’s skies.

“I was always amazed by that, and I didn’t think that I would live long enough to see another animal go extinct. Well, in the 11 years I’ve been doing the photo ark project, I’ve probably seen 10 go extinct,” Sartore said.

It was a personal crisis that gave rise to the building of the ark. Sartore was a long-time, globe-trotting contract photographer for National Geographic when his wife, Kathy, was diagnosed with breast cancer. Anchored at home to care for her and their three children he mulled a new course, one inspired in part by John James Audubon’s documentation of the birds and mammals of North America.

Aware that his animal photos resonated with National Geographic readers, Sartore decided to amass a “giant catalog” that would show the grand diversity of the most modest animals.

“My wife’s fine now but it was kind of a close call, and the photo ark was born out of wanting to do something that stuck,” Sartore said.

While his path is set for the next 10 to 15 years he estimates it will take to complete the ark project, he has a few less arduous tips for those who interested in protecting the Earth and those who dwell on it: Support your local zoo or aquarium, which help keep some animals from extinction; buy less, reuse more; plant gardens that attract butterflies and bees, critical to the environment; avoid lawn chemicals, which end up in the water supply and are fatal to fish and frogs.

Sartore insists on remaining hopeful about the future, even as he sees species vanish.

“I don’t get sad but I do get mad,” he said. “I think, ‘Let’s use this as a shining example of what not to do.’ And surely this time, people will care. Surely they’ll care.”