Crocodiles can replace each of their 80 teeth up to 50 times
The mouth is where most animals take in food, and often where they make sounds. In many animals, including ours, it is the front door of a gut with a separate exit, but in sea anemones the same opening serves both ways, and the first animals probably had no mouth at all.
The earliest multicellular animals likely fed by endocytosis, their surface cells engulfing particles and digesting them inside vacuoles, as sponges, Amoeba and Paramecium still do. Most animals now have a mouth and a gut whose lining continues from the skin, although a few parasites have lost their guts again. From earthworms upward in complexity, the embryo forms a dent called the blastopore; in deuterostomes it becomes the anus and the mouth opens later, and which end appears first is used to split bilaterians into two great groups.
Mouths vary enormously. Many molluscs scrape food with a toothed radula, insects use mandibles, maxillae and a labium adapted for chewing, piercing, sponging or sucking, and decapods have six pairs of mouth appendages. Fish draw water in through the mouth and out past the gills, and most feed by suddenly widening the pharynx to suck prey in. Many amphibians flick out a sticky tongue and swallow prey whole.
Among reptiles, only crocodilians anchor teeth in sockets, and each of their roughly 80 teeth can be replaced up to 50 times; turtles lack chewing teeth and grind plants with stomach stones. Birds have no teeth at all, relying on keratin-sheathed beaks shaped to their diet, while mammals have a mouth roofed by hard and soft palates, floored by the tongue and lined with teeth set in both jaws.
Mouths do other jobs too. Tropical crocodiles gape to cool off, mammals pant and birds flutter their throats to shed heat, and many animals bare teeth or flash bright mouth linings as a threat that can head off a fight. In humans, the tongue, teeth, lips, palate and pharynx act as articulators that shape air from the lungs into speech.
Source: Mouth
