Goblet cells secrete mucus, but in gastric glands mucus neck cells secrete mucus.
Functions of mucus :
1. Mucus lubricates the food
2. Mucus dilutes the action of enzymes so that they may not affect wall of alimentary canal. In case of duodenum mucoid fluid also protects wall of duodenum form acidic chyme.
Diphyodont is the condition of having two set of teeth during the life of an organism. For example : humans are diphyodont as they have two set of teeth namely temporary milk or deciduous teeth which are replaced by permanent or adult teeth.