Every animal excretes its waste; if it didn't, it would die. But sometimes that poop does double—wait for it—duty. Read on to discover the second careers of wombat waste, stork scat, and more. 

1. and 2. Marabou Stork and Vulture Poop // Climate Control and Decontamination

Birds can’t sweat, but black vultures, turkey vultures, and marabou storks might just have the next best thing to keep them cool: They poop on their own legs. (As anybody with a clean car can tell you, bird “poop” is actually a runny mixture of urine and feces.) Ornithologists are split on why they do this. For marabou storks, it’s believed that this practice, known as urohydrosis, makes use of evaporation to lower the birds’ body temperature. But vultures might be using it to decontaminate their legs from the bacteria they pick up after a long day standing in rotting meat.

Black vultures are also tactical pukers, using their vomit defensively “with wonderful quickness and power,” according to legendary bird man John James Audubon. It’s easy to see why that might work.

3. Baleen Whale Poop // Fertilizing Ocean Algae

Baleen whales eat krill. Krill eat algae. And algae … well, algae don’t eat anything. They're more like plants. Even so, they've got needs—sunlight and iron, both of which are found on the ocean’s surface. You can guess how the sunlight gets there, but the iron? Most of the time it comes from continents, but Antarctica is covered in ice, so no iron is entering the Southern Ocean from there. It was a mystery—until scientists analyzed tissue and fecal samples from four species of whale and seven species of krill. In the words of Australian Antarctic Division scientist Dr. Steve Nicol: “There’s huge amounts of iron in whale poo.”

Seen in reverse, the cycle seems simple. When krill eat algae, they concentrate all that algae’s iron. When the whales eat the krill, the iron gets concentrated even further. Then those whales do their business, releasing all that iron back into the water and fertilizing the ocean for generations of algae, krill, and pooping whales to come. 

4. Wombat Poop // Making Fences

Common wombats are solitary animals that, oddly, live in very close proximity. Their eyesight isn’t very good, but their sense of smell is terrific, which is why they mark the edges of their territory with 80 to 100 of these each night:

That’s right: wombats have cube-shaped poop. This is incredibly handy, since wombats like to poo at nose-level, which often means squatting atop a log, a rock, or even a large mushroom. Cylindrical feces would roll right off, but those little cubic turds stay put.

5. Pacu Poop // Planting Trees

It’s well known that certain plants need help from furry and feathered members of the animal kingdom. Because animals can walk, fly, and climb, they can carry a plant’s seeds much farther than the plant could ever take them. But let’s not overlook one of nature’s most efficient seed-spreaders: fish. Fish poop, to be specific.

A fish called the pacu gets its chance to contribute once a year, when massive flooding overtakes the wetlands of its native Brazil. The pacu might look like a piranha’s stunt double (and they are related), but it’s more of a softie, preferring the taste of ripe fruit that drops from tucum palm trees into the water. Belly full of pulp and seeds, the pacu swims for miles, through flooded forests and over watery plains. Along the way, naturally, it poops, leaving deposits of seeds in brand-new territory. The waters recede, the seeds germinate, and the pacu swims on, an unwitting hero. 

6. and 7. Rabbit and Capybara Poop // Recycling

If you’ve ever had a pet rabbit, you know where this is going. Rabbits (and capybaras, for that matter) produce two kinds of poop: hard, dry pellets; and soft cecotropes—poop for eating.

These animals are hindgut fermenters, which means that a lot of the good bacterial stuff happens in the cecum, right next to the colon, where it can’t be absorbed. Making sure none of the bacteria's good work goes to waste, a rabbit or capybara will eat its own cecotropes. Rabbits excrete theirs in what look like clusters of shiny little mucus-covered grapes. Capybaras go straight to the source, in a maneuver that calls to mind a teenager sticking his head under a Slurpee machine. (Sorry.) The nutrients are better absorbed the second time around, and everybody wins, aside from the researchers whose job is to watch this stuff for days on end.

8. Parrotfish Poop // Making Beaches

If you’ve ever enjoyed a stroll along Hawaii’s beautiful white-sand beaches, you can probably thank a parrotfish. Nearly every grain of sand on those beaches, according to biologist Ling Ong, “is of biological origin.” Translation? It’s poop.

The parrotfish, known as uhu in Hawaiian, uses its photogenic face to scrape delicious algae off coral. That beak is not terribly precise, which means these fish swallow quite a lot of coral. Bites of coral travel through the grinding jaws at the back of the fish’s throat, getting even smaller, and then—since the parrotfish has no stomach—shoot right back out into the ocean, now tiny grains of sand.

Urchins, sponges, oysters, and other sea critters all contribute, too, but none is quite so prolific as the parrotfish, which can produce up to 800 pounds of destination-wedding-worthy sand a year.

9. and 10. Bat and Tree Shrew Poop // Gardening

Of all the wily carnivorous plants out there, pitcher plants in the Nepenthes genus have got to be the craftiest. Most pitcher plants are a trap, offering passing insects a lick of nectar if only they’ll come closer. The bugs land, fall down the pitchers’ slippery sides, and end in a stew of juices that will digest them slowly. But not the Nepenthes. No. At least four species in the Nepenthes genus have evolved into full-service toilets. Woolly bats and tree shrews can safely land on the pitchers’ sturdy lips and lean over to enjoy a nectar meal. Once the animal is in this position, the perfectly shrew-or-bat-butt-sized mouth of the pitcher makes a perfect toilet. The bats and shrews partake, leave their deposits, and take off. The poop they’ve left in the pitchers provides the plants with as much nutrition as an insect feast. In fact, researchers estimate that the pitcher species get between 34 and 100 percent of their nitrogen from bat and shrew poop.

So. What has your poop done for you lately?