A small web is: crickets and mice eat plants…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A small web is: crickets and mice eat plants. A toad eats crickets. A crow eats plants and toads. An owl eats mice, toads and crows. Nothing eats the owl.
- At which trophic levels can the crow be?
- At which trophic levels can the owl be?
- How many food chains run from the plants to the owl?
Need a reminder? The key ideaShow
The trophic levels are T1 producers, T2 primary consumers, T3 secondary consumers and T4 tertiary consumers. In a web, a species can sit on more than one level. The standing crop is the biomass or the number of organisms in a unit area, and dry weight is the more accurate measure.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. The eating relations above.
Plan. The levels are T1 for plants. Each eater is one level above its food.
Step 1. (a) The crickets and the mice are at T2. The toad is at T3. The crow eats a plant (T1), so it is at T2. It eats a toad (T3), so it is at T4. The crow is at T2 and T4.
Step 2. (b) The owl eats a mouse (T2), so T3. It eats a toad (T3), so T4. It eats a crow (T2 or T4), so T3 or T5. The owl is at T3, T4 and T5.
Step 3. (c) The chains are: plant, cricket, toad, crow, owl; plant, cricket, toad, owl; plant, mouse, owl; plant, crow, owl. That is 4 chains.
Answer: crow T2 and T4; owl T3, T4 and T5; chains.
Check. The program below finds the same levels.
Discussion (0)
Log in to join the discussion.
Loading…