are reptiles of the order Testudines or Chelonii characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield. "Turtle" may refer to the order as a whole or to fresh-water and sea-dwelling testudines.

 First, the esophagus pushes the food through and into the stomach. The stomach contains acids and digestive enzymes to decompose the food. Then, the liver produces bile and transfers it to the gall bladder. Then the gall bladder transfers the bile to the small intestine. 
After, the food  travels to the large intestine, and the
food becomes a waste. Lastly, the waste product exits from the turtle's anus.

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Along with good sight these animals also possess colour vision. A chelonian will be drawn to foods that are green, red, yellow or moving and so depend greatly on their sense of sight.

 

Chelonians use smell sense also during mating and escape. During the mating season the females will produce pheromone chemicals that will tell the males when they are ready to mate. 

Chelonians lack any external ear opening. Turtles can still hear air vibrations. Their tympanic membranes are covered by a thin layer of skin that acts as an ear drum allowing the animal's to hear auditory stimuli. 

Even though they are clothed in a bony shell, chelonians are quite capable of feeling touch. This is accomplished by thin lines of nerves running all over the shell. These nerves can pick up pressure differences, but lack pain receptors. So if you were to lightly touch the shell of a turtle, it would feel you doing it. 

 While many species do possess taste buds, it is not well known how sensitive they are. Some species like the snapping turtles lack taste buds, as do many tortoises. This allows the animals to swallow food that would be considered poisonous or would bite back, without feeling to many ill effects.