Wildlife photographer Joel Sartore’s National Geographic Photo Ark turned 20 this year and reached its 18,000th animal, a critically endangered red handfish.The project aims to photograph every species living in the world’s zoos, aquariums, and sanctuaries, so the portraits can move people to care about extinction.Some animals Sartore has photographed, including the northern white rhino Nabiré and the frog Toughie, were among the last of their kind, and have since gone functionally or entirely extinct.After more than 30 years as a photographer, Sartore keeps a relentless pace and is preparing his son Cole to carry the Photo Ark forward.

For 20 years, Joel Sartore has been on a quest: to photograph every animal species in human care, and then some. This year, on the 20th anniversary of the Photo Ark somewhere in Australia, Sartore photographed the project’s 18,000th animal. He’s not totally sure which one pushed the project over the threshold, but gives it to the critically endangered red handfish (Thymichthys politus) a grumpy, red Muppet of a fish that could use the publicity.

When Mongabay asked Sartore, just a few days after the official anniversary, about the last animal he had photographed, he got very excited about a small moth on the screen door of his home in the U.S. state of Nebraska. He coaxed it into an old cup and photographed it. He was still waiting on an identification from a couple of moth experts, who, he notes, are night owls.