Biotic Components
The biotic components of an ecosystem include all the living organisms, such as plants, animals, and microorganisms. These organisms are classified based on their functional roles into producers and consumers.
a) Primary Producers (Autotrophs or Self-nourishing)
- Primary producers are mainly green plants, certain bacteria, and algae. They are capable of synthesizing carbohydrates from simple inorganic materials like carbon dioxide and water using sunlight, through the process of photosynthesis. These producers not only produce food for themselves but also supply energy indirectly to all other organisms that cannot produce their own food.
- In terrestrial ecosystems, producers include herbaceous and woody plants, whereas in aquatic ecosystems, producers are mainly microscopic algae and phytoplankton.
b) Consumers (Heterotrophs or Other-nourishing)
- Consumers are organisms that cannot carry out photosynthesis and hence depend on organic food derived from plants, animals, or both. Consumers are further classified into two broad groups: macro-consumers and micro-consumers.
(i) Macro-consumers
These are animals that feed directly on plants, animals, or both. They are categorized based on their diet:
- Herbivores (Primary consumers): Feed directly on plants. Examples: cow, rabbit.
- Secondary consumers: Feed on primary consumers. Examples: wolves.
- Tertiary consumers: Feed on secondary consumers. Examples: lions that prey on wolves.
- Omnivores: Feed on both plants and animals. Examples: humans, monkeys.
(ii) Micro-consumers (Saprotrophs, Decomposers, or Osmotrophs)
- These include bacteria and fungi, which decompose dead plant and animal matter to derive energy and nutrients. The process of decomposition releases inorganic nutrients back into the ecosystem, which are reused by producers — thus recycling matter.
- In addition to decomposers, certain soil organisms like earthworms, nematodes, and arthropods feed on detritus (dead organic matter) and aid in decomposition. These organisms are called detritivores.