• Question: what is a food chain

    Asked by 293furk43 to Sarah, Kieran, Kathryn, Joanne, Chris on 8 Nov 2017.
    • Photo: Chris Werner

      Chris Werner answered on 8 Nov 2017:

      A very good question, and a very important one! It is links in a food web from producer organisms to predators. Every organism needs something to live on, so best thing rather than making it techy is to give a good example.

      Grass grows, the first ‘trophic level’ on the food chain and the primary producer, then grass gets eaten by a grasshopper, a ‘primary consumer’ and herbivore. Then the grasshopper is eaten by a mouse, a carnivore and another consumer, who is then eaten by a snake, who is then eaten by an eagle. The food chain continues until you reach the top predator, which no-one easts, and a food chain can be long or short. That was a long one!

      A shorter one would be; grass -> antelope -> lion. No-one eats the lion! As grass is eaten by lots of animals this would expand into a food web. It gets larger around the middle and then gets smaller as you approach the top predator.

    • Photo: Sarah Guerin

      Sarah Guerin answered on 8 Nov 2017:

      Yeah Chris explained it well with the Lion-Antelope-Grass example. Humans are also the perfect example- we are at the top of our food chain, we eat animals like cows and chickens, and they eat grass and insects.

    • Photo: Kathryn Schoenrock

      Kathryn Schoenrock answered on 13 Nov 2017:

      Now that Chris and Sarah have described them I’ll mention that there is actually a really cool way to study food chains called stable isotope analysis. This is where we take a small sample of a plant or animal and see what the ratio of ‘heavy’ vs ‘normal’ atoms of carbon (13C/12 C) and nitrogen (15N/14N) are. We call atoms ‘heavy’ in nature because they have a higher atomic mass (weight is measured in Daltons). They are rarer than the ‘normal’ atoms but stay in tissue of an animal longer so if you look at a plant it will have the lowest ratio, an herbivore would have higher ratios, and a carnivore would have the highest! We also use this type of analysis to look at past climate records in plants and animals with a different atom, oxygen (18O/16O). Its a very cool way to study biology using physics and chemistry!

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