St. Patrick’s Day: 'Green' Animals That Recycle

Crabs, birds, bugs, and other species recycle human and natural waste.

St. Patrick’s Day is almost here, a holiday famous for parades, parties, and everything turning so green that it’s like looking at the world through night-vision goggles. But when we think “green” we sometimes think “eco,” so in honor of Green Day here are five of nature’s “greenest” animals, not in color but in habit. Whether it’s home decor or an entire home, these animals all recycle.

Decorator Crabs

Just like Molly Ringwald in Pretty in Pink, the decorator crab uses whatever it has at hand (or claw) to create its ideal look. For the many species of this crustacean sensation, the look is camouflage. Decorator crabs are covered with hooked hairs (called setae), nobs and spines to which they attach bits of sponge, seaweed, and even little animals like anemones. They wear them as a disguise to blend in with the surroundings. The Marine Education Society of Australasia says that these relatively common crabs are so good at not being seen that they’re only noticed when they move. Monterey Bay Aquarium says that when they grow a new shell, they won’t just trash their old home decor, they’ll take it with them, pulling the baubles off the old shell and attaching them to the new one.

<p><a href="http://www.nationalgeographic.com/magazine/2016/04/nature-urban-national-parks/">The growing popularity of city parks</a>&nbsp;have been beneficial for urban squirrel populations. These&nbsp;<a href="http://animals.nationalgeographic.com/animals/mammals/squirrel/">bushy-tailed mammals</a>&nbsp;(<i>Sciurus carolinensis</i>) thrive off access to a wide range of nut trees.</p> <p><i>These images are from the National Geographic Photo Ark, a mission to create a visual archive of the world’s species—before many of them disappear. To date, photographer Joel Sartore has already taken portraits of more than 6,000 animals.&nbsp;<a href="http://nationalgeographic.org/projects/photo-ark/">Learn more about how you can support the project.</a></i></p>

The growing popularity of city parks have been beneficial for urban squirrel populations. These bushy-tailed mammals (Sciurus carolinensis) thrive off access to a wide range of nut trees.

These images are from the National Geographic Photo Ark, a mission to create a visual archive of the world’s species—before many of them disappear. To date, photographer Joel Sartore has already taken portraits of more than 6,000 animals. Learn more about how you can support the project.

Photograph by Joel Sartore, National Geographic Photo Ark
Tallahassee, Florida

This ABC News video of decorator crabs features Jay Stachowicz of the Stachowicz Lab at UC Davis describing how some crabs will even wear anemone hats with stinging tentacles, a great way to dispose of a predator. Talk about being dressed to kill.

Arthropods

If you remember the ’70s you remember the advent of potato skins as an appetizer. You may also remember your parents noting that someone was making a fortune out of the part of the potato people used to throw away.

A number of arthropods take this “waste not, want not” attitude when it comes to their own outer skins. Lobsters, for example, grow by molting. The University of Maine’s Lobster Bulletin says they shrink their appendages by drawing blood from them; they then take in excess water, which causes the old shell to crack down the center while their new shell is growing underneath. They will then pull themselves out of the old shell and hide for about a week until the new one hardens.

But lobsters won’t just throw away their old shells: It will be repurposed as food, a meal full of calcium that the lobster can use to help toughen up that new shell.

Centipedes also grow by molting and sometimes eat their old exoskeletons for nutrients, as in this video from the California Science Center. Arizona State University says that monarch butterfly larvae eat the remains of the egg out of which they hatch, and will often eat the skins they shed in the five molting processes they undergo on the route to monarch-y.

Aren’t you glad you can just call out for pizza?

Birds

Cigarettes are for the birds. No, really.

Instead of going to Ikea like everyone else, some species of city-dwelling birds line their nests with discarded cigarette butts, something some species do with parasite-repelling vegetation. A study by researchers at the National Autonomous University of Mexico published in Biology Letters found that the more the nests abounded with cellulose acetate, a component in cigarette filters, the fewer parasitic mites were present. They also tested the nests of house sparrows and house finches by putting heat-generating traps in the nests to attract parasites. The nests contained either smoked or unsmoked cigarette butts. Those with the unsmoked butts caught more than twice as many parasites, the CBC reports. That suggests that parasitic mites may be turned off by greater amounts of nicotine. (Related: “Animal Pharm: What Can We Learn From Nature’s Self-Medicators?”)

<p>This shot of a gray heron in Hungary won a silver award in the attention to detail category.</p>

This shot of a gray heron in Hungary won a silver award in the attention to detail category.

Photograph by Ahmad Al-essa

And that’s how birds take human trash and turn it into their own personal Purell. Kind of makes us look like the dirty birds, doesn’t it?

Burrowing Owl

You probably wouldn’t think of an owl living in a burrow any more than you’d think of a prairie dog living in a tree. But burrowing owls do, indeed, nest underground, and according to the Cornell Lab of Ornithology, they don’t let abandoned real estate go to waste. The only owls ever seen to hang out on the ground—or during the day, for that matter—they are capable of digging out their own burrows. But they’ll also use homes left over by prairie dogs or other animals.

They may recycle something else, too: animal dung. Burrowing owls tend to make a welcome mat of the stuff. National Geographic reported in 2010 on a study showing that the owls may be using this enticing decor to lure dung beetles, their favorite food. Douglas Levy of the University of Florida said it’s not certain they’re doing it for that reason or that they’re aware of it; however, an experiment showed that owls with dung at their doorways ate ten times more beetles and six times more dung beetle species than those whose front yards were not so festooned.

It still sounds like they’re pretty green on at least two fronts. Bonus: They’re as cute as a dung beetle’s ear.

Ant-Snatching Assassin Bugs

Gather ’round, designers! Your next Project Runway challenge is to make a camouflage coat using only bug corpses. If you need some inspiration, check out the ant-snatching assassin bug.

Assassin bugs costume themselves in the remains of their prey, as Ed Yong noted in 2010. They grab their insect prey, stick their sucking mouth parts into it, and pump it full of paralytics and digestive enzymes. For dinner, they suck out the liquefied insides. But instead of just leaving the corpse lying there, they put it to good use. They pile the emptied husks of the dead onto their backs, which seems to help them avoid predation.

Yong reported that researchers from the University of Canterbury tested the effectiveness of cadaver couture by unleashing jumping spiders on assassin bugs, some of which were “dressed” and some of which weren’t. The corpse-free bugs were attacked ten times more often, even if they were dead.

Bonus: They secrete a sticky thread from their backs, which they use to secure the corpses. So they really make their outfits with thread.

Now that’s a dinner jacket.

Black-browed Barbet. Kaohsiung, Taiwan
Black-browed Barbet. Kaohsiung, Taiwan
Photograph by Boris S., National Geographic Your Shot

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