foodchain

A food chain is a linear sequence of organisms through which energy and nutrients pass as one organism consumes another. In most ecosystems, the chain begins with photosynthetic producers such as plants, algae, or some bacteria that capture sunlight to create organic matter.

Trophic levels include producers at the base, primary consumers (herbivores) that eat producers, secondary consumers (carnivores or omnivores that eat herbivores), and tertiary consumers (top carnivores). Detritivores and decomposers, such as worms and fungi, play essential roles by breaking down dead material and recycling nutrients. While many organisms feed across levels, a food chain remains a simplified representation of feeding relationships.

Energy flow is central to food chains. Solar energy is captured by producers and converted to chemical energy. With each transfer to the next trophic level, only a portion of energy is retained; the rest is lost as heat or used in metabolism. A common rule of thumb is that about 10% of the energy moves to the next level, which helps explain why food chains are relatively short.

Food chain versus food web: A chain shows a single pathway of energy transfer, whereas a food web is a network of interconnected chains that better reflects real ecosystems, where organisms may have multiple dietary sources and roles.

Significance and limitations: Food chains illustrate feeding relationships and energy flow, but they are simplified models. They do not fully capture detrital pathways, nutrient cycling, or spatial dynamics. Human activities, such as habitat destruction and pollution, can disrupt chains and cause cascading ecological effects.