Mechanical digestion

Question

What do you mean by mechanical digestion? In arthropods, molluscs, earthworms, vertebrates and birds, which organ participates respectively in this type of digestion?

Answer 1

Mechanical digestion refers to fragmentation of the food aided through the specialized physical structures, like teeth, previous to extracellular digestion. Mechanical fragmentation of the food helps in various digestive enzymatic reactions since it gives larger area for the contact between the enzymes and their substrates. In some molluscs, mechanical fragmentation is done through the radula (teeth-like structure). Some arthropods e.g.  Dragonflies, lobsters and, have mouthparts which do the mechanical digestion of food. In earthworms and the birds, mechanical digestion is done by an internal muscular organ. In manipulate vertebrates there exist mandibles and chewing muscles in order to triturate food previous to the chemical digestion.