And the answer: flamingos.
Born with gray plumage, flamingos get their vibrant hues from their carotenoid-rich diet of brine shrimp and algae. Enzymes in the flamingos’ livers break down the compounds into pink and orange molecules, which spread to the birds’ feathers, legs, and beaks.
As it turns out, carrots have more in common with flamingos than you might have previously thought! Carotenoids, as the name suggests, are different types of pigments commonly seen in fruits and vegetables such as carrots, pumpkins, sweet potatoes, tomatoes, and squash. There are over 600 different types of carotenoids, including those which exist in the microscopic algae that brine shrimp eat. When flamingos dine on this shrimp, their bodies metabolize the pigment, resulting in pink feathers.
Flamingos enjoy meals of algae, seeds, tiny crustaceans, and fly larvae—food sources all found in brackish, shallow waters. Although they tend to prefer a mix of salty and fresh water, some flamingo species live in extreme environments such as salt lakes. The salt content in these lakes is so high that it is uninhabitable for most species, as some even risk corrosive skin burns. Thankfully, flamingos’ tough skin and scaly legs prevent injury, and their unique ability to drink nearly boiling water from springs and geysers makes the hot, salinated water no problem at all. Flamingos are also incredibly adaptable—even if no freshwater is available, they can use glands in their head to remove salt, draining it out from their nasal cavity!
Famously, flamingos are able to sleep standing on just one leg. Research suggests this habit is an evolutionary reflex that helps the flamingo to save energy and preserve body warmth, as well as maintain balance (though, that last point seems counterintuitive to me…). However, while this theory is widely accepted, scientists continue to theorize on this puzzling behavior.
Learn more about flamingos here.