2. Trophic levels

Hello readers,
Welcome back to the VOICEofप्रकृति  !

                                 (read as : Voice of Prakriti)

Before I start, I'd like to thank everyone for the positive response I received on my last blog. The very objective of this page was to reach out to people like you and have (eco)nversations. (Get it ? wordplay on 'eco' and 'conservations', hehe.) Today I've tried my best to dial down some technical info into simple terms, which is quite important as we slowly start to see the bigger picture. 

I am sure trophic levels were introduced as a concept in school. But for people who don't know trophic levels, we need to first have a look at the 'food chain'. 

Food chain is your simple concept of "who - eats - who". A common example would be grass🪴 being eaten by rabbits🐇, rabbits being eaten by snakes🐍, snakes being eaten by eagles🦅. (I am using emojis to make this fun.)

So, scientifically put, Trophic levels are hierarchical levels within an ecological community. They represent the position of organisms in a food chain, based on their feeding relationships. This simply means that plants are always placed first (since they are primary producers), then herbivores, then carnivores, and so on. There is a clear hierarchy that is visible, they don't shuffle amongst themselves.( For eg. Grass won't eat a snake. 🐍-->🪴❌)  

There are generally 4 main trophic levels – 

Fig 1. Trophic level flowchart 

The first and lowest trophic level is made up of producers, like green plants🪴, which have the ability to make their own food. Producers don't have to depend on other organisms for food. Hence, they are also called autotrophs ( autotroph - an organism that can produce its own food using light, water, carbon dioxide, or other chemicals). 

Herbivores (or plant eaters), make up the second level as they consume plants 🐄🐐🐇🐑. Hence, they are also called primary consumers. The third level consists of carnivores that eat herbivores; we call them secondary consumers🐍🦁🐆. The fourth level includes secondary carnivores that feed on primary carnivores, and are also known as tertiary consumers 🦈🦅.

Organisms that eat other plants or animals for energy and nutrients are collectively called heterotrophs.  (Word origin - greek; hetero - “other” and trophe -“nourishment.”)

It is important to note that the concept of trophic levels is an attempt by us humans to compartmentalize nature. However, nature isn't so simple. There are some animals, called omnivores that can eat both plants and animals. Finally, decomposers like bacteria and fungi break down dead plants and animals, returning nutrients to the soil for producers (like plants) to use again. 

In reality, food relationships between organisms are complex, and so we observe something called 'food web' instead of simple food chains. This is because many organisms can eat more than one organism. 

        

        🦅 Eagle              🐅Tiger  ↔️  🦁 Lion

                 ↘           ↙            ↙       ↘   

                     🐇 Rabbit   🦌 Deer 🐃 Water Buffalo

                                        ↘             ↙           ↙      ↖ 

                       ↙  🌱 Grass/Plants            🐊Crocodile 

         Snail 🐌                  ↖          ↖             ↙

                    ↘         🦀 Crab          🐢 Turtle

                                  ↓             ↙

                               🐠 Fish      

                   Fig 2. Food web (using emojis)

Now that we have cleared/revisted the basics, I would like to ask you a question.

Where do you think humans are placed on the food chain ? 

I'd like to pause here and let you think for sometime.
See you in the next blog where we analyze the position of human beings in a food web :)