Nature is full of strange adaptations and bizarre body structures. Some animals have their anus in totally unexpected places — or use it in ways you’d never imagine.
1. Sea cucumber – a multifunctional rear end
The sea cucumber doesn’t just use its anus for waste elimination — it also breathes through it. By pumping water in and out of its anus, it absorbs oxygen. And if that’s not weird enough: some fish, like the pearlfish, use the sea cucumber’s anus as a hiding place.
2. Turtles – breathing through their butts
Some aquatic turtles, such as the Red-bellied Short-necked Turtle, can breathe through their cloaca — an opening used for both waste and reproduction. They absorb oxygen from water via this organ, allowing them to stay underwater much longer. A truly fascinating adaptation!
3. Sea hares – anus on the neck
The sea hare, a type of sea slug, has its anus located just behind the head — almost on its neck. This strange placement results from a twisting of their internal organs during development. Not exactly convenient, but it works for them.
4. Mangrove tree crab – belly-bottomed bathroom
The mangrove tree crab has its anus on the underside of its belly rather than at the back. This allows it to get rid of waste while clinging tightly to trees or rocks — perfect for its vertical, arboreal lifestyle.
5. Birds – one hole for everything
Almost all birds have a cloaca — a single multi-use opening for waste, mating, and laying eggs. While not an unusual location, the fact that it handles everything makes it noteworthy.
6. Feather stars – pooping through waving arms
Feather stars, relatives of starfish, have their anus on the top side of their body, near the mouth. Even weirder: they use their long, waving arms to spread their feces into the water, which helps keep them clean — in their own very peculiar way.
7. Squid – hidden exit near the jet stream
In squid, the anus is located deep inside the mantle, right next to their jet stream — the siphon they use for movement. This means they eject waste along with their propulsion water, allowing for fast escape and easy clean-up all at once.
8. Sea urchin – anus on top
The sea urchin (Echinoidea) may look simple, but its anatomy is surprisingly unusual. Its anus is located on top, right in the center of its spiky dome. This isn’t just random: it allows for efficient waste disposal, even in fast-moving currents. In some flattened species, like sand dollars, waste exits along beautifully arranged grooves. It’s both practical and bizarre — the perfect match for sea urchins.
