An ant colony builds bridges out of its own living bodies, then dismantles them
Army ants crossing a gap in the forest floor will link their own bodies, leg to leg, into a bridge for the rest of the colony to walk across. Researchers found the ants constantly adjust the bridge's length and position as traffic changes, effectively weighing the shortcut's benefit against the cost of tying up workers as living infrastructure — and will abandon a bridge the instant foot traffic drops enough to make it not worth the workers it costs.