The shape of the mouth the jaws and the teeth of animals depend upon the kind of food they eat. Some animals (like frogs/snakes) swallow their food whole. They do not chew. Their teeth present in the upper jaw are only for preventing escape of the prey from the mouth and not for chewing or biting.
Grass-eating animals have sharp front teeth to bite off plants (like cows/horses). They have strong and broad back teeth(molars) to grind their foods. They have no teeth for tearing food. There is space between the front teeth and the back teeth.
Some of these grass-eating animals first bite off the grass with their front teeth and swallow it quickly. After some time they bring up small amounts of food from their stomach back into their mouth. Then they keep on chewing it well. This is called Chewing the Cud
Flesh-eating animals (like tigers/lions) have special long pointed teeth to tear the flesh. They also have strong grinding teeth to chew the meat and bones.
Some animals eat seeds, fruits and plants (like rats/squirrels). They have pair of very sharp front teeth both in the upper and the lower jaws.
Some animals like liquid foods (milk) suck from their mothers (like kittens/calves/foals). Like dogs, cats lick milk and water with the help of their tongues.
The mouth parts of the butterfly are modified into a long sucking tube with which it sucks nectar from flowers. This tube is known as the “Proboscis”
. When not in use it remains coiled like a watch-spring below the head. When it wants to suck nectar, the tube is uncoiled and pushed into the flower.
Insects (like mosquitoes/bees) have mouth parts (proboscis) adapted for piercing and sucking
Birds eat various kinds of food. Some birds feed on animals only, while others are strictly vegetarian. Birds have beaks, specially designed to catch or pick up their foods.
Eagles, hawks and owls feed on small animals like rats so they have hooked beaks, while the beaks of ducks are broad and notched for scooping and straining the mud.
The beaks of sparrows are short and straight and are useful for crushing seeds. The woodpecker has a chisel-shaped beak for drilling into trees to look for insects.
Some birds use their feet and sharp claws (eagles/vultures) to capture their prey.