Flamingos are weird birds. Take their legs, for example. What most of us think of as a flamingo's knee is actually it's heel. What looks to the casual observer like an ankle is actually the beginning of a flamingo's toes. They're also prone to perching on one leg, and sport bright pink plumage.
But there's a decent chance you already knew some (or maybe all) of those weird flamingo facts, so here's one you probably didn't know: Flamingos have erectile tissue in their mouths. Yes, really. Scientific American's Becky Crew explains:
[A study], published in Anatomical Record in 2006 by biologist Casey Holliday and professor of anatomy Lawrence Witmer from Ohio University, found erectile tissue in the flamingo's beak. Flamingos are known for their odd way of eating — they stand in shallow water, and put their beaks in an almost upside-down position in the water to catch food as it floats by. Their tongues act like pumps that manipulate the water, squeeze the food out and trap it. When Holliday and Witmer constructed a 3D model of a flamingo's head, they noticed large, oval-shaped masses of erectile tissue on the floor of its mouth and running along either side of its tongue. Just like the erectile tissue in a man's penis, this stiffens when filled with blood — like when the head is tipped upside-down — and helps to strengthen and support the floor of the mouth and tongue when the flamingo is feeding. "We suspect this stabilises the mouth and tongue and helps with the peculiar way that flamingos eat," said Witmer. "It's an important new piece of the puzzle of flamingo feeding – frankly, a piece we hadn't known was missing."
Read more about the explanations behind flamingos' bizarre anatomies — including why they stand on one leg, and ho they first acquire their distinctive pink pigment (flamingos are born white) — over at SciAm.