Page 2 - 2. Lesson notes-Food chain and Food web
P. 2
In ecosystems, different food chains may have two, three, four or maximum five trophic
levels. Such food chains are depicted in the above figure. Accordingly, a food chain may end
at the –
(i) herbivore (primary consumer) level,
(ii) primary carnivore (secondary consumer) level,
(iii) secondary carnivore (tertiary consumer) level, or
(iv) tertiary carnivore (quaternary consumer) level.
Trophic levels
The distinct sequential steps in the food chain where transfer of energy occur are
referred to as different trophic levels.
For example, green plants (producers)- form the first trophic level-the producer level; the
plant eaters (herbivores), also called primary consumers, belong to second trophic level- the
primary consumer level; and the flesh eaters (carnivores), also called secondary consumers,
represent the third consumer level-the secondary consumer level and so on.
