Several animals don't need to chew in order to eat. Many of them have no teeth at all, but the majority have teeth designed only for ripping and shredding food. In most cases, these animals start the digestion process in the stomach or crop rather than in the mouth.
Snakes and Their Amazing Jaws
Snakes swallow things whole because they don't have teeth designed for chewing. In fact, their fangs curve backward to push food toward the throat. Not all snakes have fangs, but they all have lower jaws connected by stretchy, flexible tendons. Snakes can separate the sides of their jaws to allow for large prey and can move each side of the jaw independently to "walk" the mouth around food.
Barnyard Birds and Beyond
Some birds, such as geese, have serrated edges on their bills that can rip and shred food; but others, such as ducks, swallow everything whole. Ducks wash their food down by dipping it into water and swallowing it. Chickens and owls, among others, have sharp, pointed beaks that can pull things apart, but for the most part they also swallow everything whole. Birds who swallow food whole have stones in their crops to grind the food.
Down by the Pond
Since frogs have no teeth, they must swallow their insect and small animal foods whole. They have sticky tongues that snatch prey. Their tongues are attached to the front of the mouth rather than to the back, and they curl backward to enable frogs to swallow them. Most lizards have no teeth; they kill their prey by biting down hard and crushing the insects or small animals to death.
Not Whole, But Not Necessarily Chewed
A few animals don't eat food whole, but they don't chew it like you do. Cats only partially chew their food. They basically break it into smaller chunks and swallow it as their teeth are designed for biting and shredding rather than chewing. Dogs chew plenty, but they don't necessarily chew items before swallowing if they're small or if they're voracious. Crocodiles and alligators don't chew; they rip and tear and crush; and swallow huge chunks. That's true also of sharks.
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