Definition of Herbivores

Organisms that depend only on green plants or plant produce for their nutrition
For Example: Cow, goat, rabbit, etc.

More About Herbivores

  • Herbivores are the second level of food chain and feed on the autotrophs (plants)
  • Thus they are the primary consumers of food chain of an ecosystem
  • Herbivores like squirrels eat grass and small plants near the ground and are called ‘grazers’. Herbivores that eat leaves, shoots, and twigs are called 'browsers’
  • Very large animals like elephants, rhinos, and moose are grazers and browsers
  • Herbivores have the capacity to digest the carbohydrates produced by the plants through photosynthesis
  • They make the carbohydrates available to the rest of the members of food chain
  • Thus herbivores are the important link in a food chain
  • Herbivores are directly related to the producers, meaning the decrease or increase in the number of green plants, will decrease or increase respectively the number of Herbivores
  • The anatomy and physiology of the herbivorous animals have adapted to the plant material
  • The teeth of herbivores are adapted to crushing and grinding mechanism
  • In addition to the major bio molecules such as carbohydrates, fats, proteins, nucleic acids, plants have Cellulose in abundance
  • The cellulose is present is cell wall of all the plant cells
  • Cellulose is a long linear polysaccharide chain linking the glucose units and is not easily digested
  • It can be broken down mechanically but it take lot of chewing time and energy
  • It is very difficult to break the links between the sugar molecules to release energy
  • The other way is fermentation by enzymes and only the bacterial enzyme can break them
  • Cellulase is the enzyme required for digestion of Cellulose
  • The herbivores do not have this enzyme required for the breakdown (digestion) of cellulose in their digestive system
  • However their digestive system harbours the bacteria and other microorganisms required for cellulose digestion
  • These microbes are present either in the rumen or in the caecum, known as functional caecum
  • Thus bacteria and Herbivores share a symbiotic relationship between them
  • Both mechanical chewing and the fermentation is a time consuming process
  • To overcome these problems, herbivores have evolved in many ways
  • One of them is that they chew the food roughly for the first time and swallow it
  • They regurgitate and chew it for the second time and make the food soft
  • The second chew is called cud
  • Another evolution is that it has a long digestive tract, especially caecum for the long time required for fermentation process
  • The feeding strategies are of different types such as
    • Feeding on fruits known as Fugivores
    • Feeding on seeds known as Granivores
    • Feeding on leaves known as Folivores
    • Feeding on wood known as Xylophage
    • Feeding on nectar known as Nectarivores
  • The feeding strategies differ among the herbivores.

Question related to herbivores:

1) Which among the following have microbes in their digestive tract for digesting cellulose?

a) Autotrophs
b) Herbivores
c) Carnivores
d) Omnivores

Solution: (b) The Herbivores have microbes in their digestive tract to digest the cellulose present in the plant material eaten by them.