In a food chain the “herbivores are called connecting link”, why ?
In a food chain the “herbivores are called connecting link”, why ?

Herbivores are key members of the food chain because they eat plants to digest the carbohydrates produced by photosynthetic processes. Carnivores eat herbivores for the same reason, although omnivores get their nourishment from both plants and animals. 

Herbivores are known as the principal consumers in the food cycle because of their capacity to thrive entirely on rough and fibrous plant debris (chain).