Why do flamingos filter-feed with their heads upside down?

Flamingos have unusual beaks that are adapted for filter-feeding. The shape of the bill works most efficiently when the head is inverted, allowing the bird to pump water and mud through internal filtering structures. Tiny organisms such as algae, brine shrimp, and microscopic crustaceans are trapped and eaten. This feeding style is supported by their long legs, which let them wade in shallow lakes and lagoons. Their famous posture is therefore not just quirky—it is functional.