Good public sanitation is a mark of advanced civilizations. Humans have dealt with the “bathroom problem” mainly by burying, flushing, or otherwise sequestering our waste products in some far off, out-of-sight, out-of-mind location. In this way, we’re similar to mole rats that build specialized “latrine chambers” in their underground habitats. A new paper in Animal Behavior examines alternative ways to handle the sanitation issue, developed by some of the world’s most sophisticated societies: eusocial insects like ants, bees, and wasps. One strategy involves something known as the “blind gut.”
Colonies of eusocial insects can contain millions of individuals. Because dropping feces at will would cause a serious toxic hazard, many species have developed a way of holding it in for a really long time. The youngsters, or larva, of the order hymenoptera, have a “blind gut,” meaning one that does not connect the mouth with the anus. Essentially, this means their waste products are trapped inside their bodies for weeks to months, or the entire duration of the larval stage. Only when they pupate (when the larva changes into the adult form), does their waste get expelled in one big, stinky pellet known as the meconium. In the honeybee, the meconium is expelled during its first flight out of the nest. (Imagine human teenagers holding it all in until right before they leave home for college…) After the meconium is quickly disposed of, the adult insects develop a normal continuous gut.
Researchers propose that a single large pellet requires less time and energy to deal with than many smaller pellets. So the “blind gut” was an important evolutionary adaptation for social living and for allowing species to build long-term nests.
Termites, another highly social insect, don’t use the meconium strategy. Instead, termites have special bacteria in their guts that render their feces unusually sanitary and pathogen-free. As a result, termites actually use their own feces to construct their nests, making them possibly the world’s most sustainable architects. Other social insects have developed waste management systems that designate certain individuals as life-long sanitation workers. In colonies of gall aphids and leafcutter ants, “pooper scoopers” spend their days collecting and removing waste from the nest, and are often shunned by other members of the colony.
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