The Insect That Breathes Through Its Butt

In the quiet streams and still ponds of the world, a tiny insect nymph drifts below the surface—unnoticed, fragile, and clinging to the rocks. At a glance, it looks ordinary. Just another aquatic creature in a vast world of bugs.

But there's one detail that sets it apart from almost every other animal.

It breathes through its butt.

Yes, you read that right.

While most animals use lungs, gills, or spiracles to take in oxygen, certain insects have evolved to extract oxygen through their rectum. It sounds like the punchline of a weird science joke—but it’s 100% real.

And in the world of insect oddities, this might be one of the strangest yet smartest adaptations ever discovered.

Meet the Mayfly Nymph

One of the best-known examples of this bizarre breathing method comes from the mayfly nymph, an aquatic insect that spends most of its life underwater before emerging as a flying adult.

In this underwater stage, the mayfly has to find a way to get oxygen. Unlike fish, it doesn’t have gills in the traditional sense. Instead, it uses delicate filament-like structures located along its body.

But some species have developed a more surprising strategy: using their hind end as a breathing tool.

How? Through rectal gill structures—tiny, feathery appendages located near the anus that pull in water, extract oxygen, and push it back out again.

It’s basically like having a built-in water pump at the rear.

Why Breathe Through the Back?

You might be wondering—why would an insect evolve to breathe through its bottom?

In aquatic environments, oxygen levels can change rapidly. Some water bodies are stagnant, warm, or filled with decaying matter, which reduces the oxygen content.

In such conditions, insects need to adapt fast to survive. Rectal breathing provides a more controlled, high-efficiency method of drawing in water and absorbing oxygen.

It also allows the insect to stay hidden and still in its environment—perfect for avoiding predators.

So even if it sounds funny to us, for the mayfly nymph, it’s pure genius.

Not Just Mayflies: Enter the Dragonfly Nymph

Mayflies aren’t the only insects using this method. Dragonfly nymphs, some of the fiercest predators in the freshwater insect world, also use rectal breathing.

And they take it even further.

Inside their abdomens, they have a muscular chamber that works like a jet propulsion system. They suck in water through their rectum, extract the oxygen through internal gills, then forcefully expel the water—allowing them to jet forward at high speed.

Yes. They literally breathe through their butt and use it to zoom through the water like a rocket.

It’s equal parts weird and brilliant.

Breath and Blast: Double Function Design

The dragonfly nymph’s rear chamber is a multi-purpose design:

• Oxygen exchange: Allows the insect to breathe underwater in low-oxygen environments.

• Locomotion: Acts like a jet engine for escape or ambush.

• Efficiency: Everything happens inside the body, minimizing exposure to predators.

No wasted space. No unnecessary movements. Just pure functional evolution.

And it’s all happening at the tail end of a tiny bug.

Temporary but Powerful

It’s important to note that this strange breathing method is temporary.

Once the insect matures and leaves the water, it no longer breathes through its butt. The adult forms of mayflies and dragonflies develop standard air-breathing systems—spiracles on their thorax and abdomen that let them take in oxygen from the air.

But while they're nymphs? Their backsides do all the work.

So for a brief but important stage of life, these insects rely on one of nature’s most bizarre breathing methods.

Nature’s Ingenuity, One Bubble at a Time

When we think of breathing, we think of lungs, nostrils, gills—things at the front of a creature. But nature doesn’t always follow the rules we expect.

Sometimes, survival means turning things around. Literally.

From the dragonfly's internal jet engine to the mayfly’s butt-gills, these insects prove that evolution isn’t just creative—it’s relentlessly efficient.

So the next time you spot a tiny bug drifting in a stream, remember:

It might be breathing… in the weirdest way imaginable.

And it's perfectly fine with that.