The extinction of species is for many an abstract concept. National Geographic photographer Joel Sartore set out to personalize the issue by taking studio portraits of all 12,000 captive species on the planet. 
Over the course of 11 years, he has visited more than 200 zoos and aquariums in the United States - and many more overseas - to greet and document his subjects. Many of them are rare - and some are likely to vanish before the end of the century. 

So far, Sartore has photographed 6,200 species, which leaves him with approximately 6,000 others to capture over the coming 15 years. 
Documenting animals in this way, Sartore says, can hook people emotionally, and bring them inside the "tent" of conservation. 

To say that time is running out for species captured in the Photo Ark is not an exaggeration. Only hours after speaking with Sartore, one of his subjects - Toughie, the world's last Rabbs' fringe-limbed tree frog - died at his home in the Atlanta Botanical Garden. It marked the end of the species.

DW: What is your personal connection to frogs?

Joel Sartore: Frogs are an ancient type of animal, yet so delicate. They take in toxins through their skins, and must have the right temperature, rainfall and even humidity to thrive and breed. With climate change, pollution and now a fungus that's sweeping the globe, many species of amphibians are now at risk of extinction. This is something I hope the world would care about if only they knew. That's where the Ark comes in.

What was the genesis of the Photo Ark?

Joel Sartore: My wife was treated for breast cancer, which "grounded" me from going on National Geographic Magazine assignments for a full year. During that time, I thought about a way my work could make a lasting difference. 

I came up with the Photo Ark as a way of getting the public to finally look species in the eye and get them to care about the extinction crisis. That was 11 years ago, and I've been focusing nearly all of my efforts on the Photo Ark ever since.

The scope has increased dramatically over time. What started out with a handful of portraits at the Lincoln Children's Zoo near my home has grown into a phenomenon - images are being projected onto the United Nations and Empire State Buildings, as well as St. Peter's Basilica at the Vatican. 
The photos have been used in anti-ivory campaigns and in motion pictures. Let's hope it's enough to do some good and actually save some of these species we're profiling.

What was the first shoot like? How did your approach to photographing the species change over time?

The very first shoot was a naked mole rate at the Lincoln Children's Zoo. Their curator found a white cutting board back in the zoo's kitchen and we used that as a background. We also did a couple of blue and black poison dart frogs that day. 
Today's shoots are much more heavily researched and thought out. The goal is to work quickly and efficiently so as to cause minimal interruption in an animal's routine.

Why did you choose to photograph these species in the studio? 

We think of it as a roving studio, actually photographing the majority of these animals right in the zoos, aquariums or wildlife rehab centers where they live. We bring our backgrounds and lighting to them in order to get the clearest photos with the most detail possible. 

What is the process for photographing each subject?

First, we work for weeks or months in advance with the zoo we hope to visit, learning what species they have that we could bring on board the ark. Of those species, we find out from the zoo which animals could participate in the shoot. Many are hand-raised and don't mind the process - while some ungulates, for example, would be too skittish to even attempt to photograph.

Once we have our short-list of animals we hope to photograph, we have two basic setups: a tabletop-sized, cloth shooting tent that smaller animals are shifted into, like frogs or small birds and rodents. For larger animals, we'll outfit an off-exhibit space with a black or white background and simply have the zoo staff shift the animal into it, often using food as a motivator to move into our temporary studio. Either way, the entire shoot lasts just a few minutes.

In viewing the portraits I have two reactions: how beautiful, and how sad. It may be the studio setting, out of their natural habitat, that brought home the sense of loss - that these beautiful creatures will soon vanish. What reaction did you want to elicit from viewers? 

The black and white backgrounds serve two purposes: to eliminate all distractions and actually get a good look at creatures that may be too small or too well-camouflaged to see otherwise, and also to level the playing field across all creatures, great and small. 

A mouse is every bit as important as a tiger, and a minnow is as intricate as an elephant. All are of equal size and importance in the Photo Ark. Since it's really true that the little creatures run the world's ecosystems, it's time we gave them all some respect.

Do you prioritize the subjects based on how quickly they are to go extinct? 

Yes I do prioritize, all the time in fact. If something is extremely rare, I move on it as quickly as possible. The one northern white rhino at the Dvur Kralove Zoo in the Czech Republic last summer was an urgent case, and she has since passed away. Now there are just three left.

Joel Sartore is an American photographer and contributor to National Geographic magazine. To learn more about National Geographic Photo Ark and how to support the project, visit donate.nationalgeographic.org/photo-ark.