Question

1.Symbiosis means “living together” and we talked about several types of symbiotic interactions that happen in communities. Name ONE type of symbiotic interaction and give me an example.

2.What happens to energy as it moves through the trophic levels of an ecosystem? What happens to nutrients as they move through an ecosystem?

Answer 1

1. Symbiosis is the long term coexistence of two organisms, termed as the symbionts, to share or compete for resources and nutrients. These could be ectosymbiotic, where symbionts exist outside one another, or endosymbiont, where one symbiont exists inside another. They could belong to the same species or different species and might be singularly dependent, where one symbiont is benefited, or mutually, where both the symbionts are benefited. Based on this, there are different types of symbiotic relationships:

1. Mutualism: Both symbionts benefit from the relationship. This relationship could be endosymbiotic or ectosymbiotic. An example would be, the clownfish and the sea anemone with stinging tentacles where the clownfish protects the sea anemone from fishes that could eat it, and in turn, the sea anemone provides shelter for the clownfish. (This relationship is shown in Finding Nemo!)

2. Commensalism: One symbiont benefits while the other is not positively/ negatively affected. For example, spiders that live on plants use them to build their webs. The plant here is neither benefited nor harmed.

3. Parasitism: One symbiont benefits while the other suffers a loss. A common example is a mosquito. The insect feeds on the blood of an organism. Here, the mosquito benefits while the host-symbiont suffers.

[NOTE: Please choose one of the examples for your answer.]

2. A trophic level is the position an organism, in an ecosystem, has on the food chain. There are five trophic levels namely, the producers, the primary consumers, the secondary consumers, the tertiary consumers, and the apex predator. Energy and nutrients move along the trophic levels from producer to primary consumer and so on.

Energy is synthesized in a food chain/ web by the producers (plants/ algae) through photosynthesis. As the energy is transferred from one trophic level to another, a part of it is lost as it moves up. This is represented in an energy pyramid diagram and the efficiency with which the energy is transferred is called ecological efficiency.

The nutrients, on the other hand, move along the trophic levels and are recycled through decomposition, where they are used up by the plants (producers). Hence, nutrients are not lost but they cycle through the food chain/ web.