Trophic levels describe the position an organism occupies on the food chain, and it's determined by its feeding habits. Primary producers are the foundation of these food chains, because they can generate biomass from inorganic matter to support all other trophic levels. Primary producers are autotrophs, or self-feeders. These are mainly photosynthetic organisms, but can also be chemoautotrophs, like the archaea and bacteria that form the foundations of ecosystems around deep-sea hydrothermal vents. Primary consumers feed on primary producers, and these are usually things like herbivores that feed on plants. These and other consumers are considered heterotrophs because they're organisms that cannot fix carbon from inorganic sources, like what happens in the Calvin cycle of photosynthesis. They need to use carbon for growth, so they must consume organic matter, in many cases consuming other organisms. Secondary consumers are generally carnivores that feed on primary consumers, and tertiary consumers are carnivores that feed on other carnivores. As you can see, we are working our way up the food chain, and here in our little food chain model, we have our first level, this is our primary producer. Our primary consumer here at the second level, our secondary consumer here at this third level, and our tertiary consumer here at this fourth level. What is missing from this food chain that is very important, as you can see over here, are the decomposers. The autotrophs, the producers, get energy from the sun, and they use that to create biomass that will feed herbivores, and those herbivores will feed carnivores. However, the decomposers return all of that organic matter back into the nutrient pool. They serve an incredibly important role, as they return matter back to be used by other living organisms. They are essentially recyclers. We call the decomposers detritivores because they consume detritus. They are heterotrophs that consume detritus, which is non-living organic material, such as dead organisms and organic wastes like feces. The food chain, as we just saw right here, is a linear network of trophic levels. We often look at a grazing food chain, which has primary consumers feeding on plants. However, we can also create a decomposer food chain, where the primary consumers actually feed on dead plant matter, and we call those primary decomposers. Food chains are linked together, both grazing and decomposing food chains, into a food web, which is a much better representation of the interactions between the different trophic levels in an ecosystem. Here, I have a picture of some nice primary decomposers, these fungi that are going to eat dead plant matter. With that, let's turn the
Table of contents
- 1. Introduction to Biology2h 40m
- 2. Chemistry3h 40m
- 3. Water1h 26m
- 4. Biomolecules2h 23m
- 5. Cell Components2h 26m
- 6. The Membrane2h 31m
- 7. Energy and Metabolism2h 0m
- 8. Respiration2h 40m
- 9. Photosynthesis2h 49m
- 10. Cell Signaling59m
- 11. Cell Division2h 47m
- 12. Meiosis2h 0m
- 13. Mendelian Genetics4h 41m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses16m
- Test Crosses14m
- Dihybrid Crosses20m
- Punnett Square Probability26m
- Incomplete Dominance vs. Codominance20m
- Epistasis7m
- Non-Mendelian Genetics12m
- Pedigrees6m
- Autosomal Inheritance21m
- Sex-Linked Inheritance43m
- X-Inactivation9m
- 14. DNA Synthesis2h 27m
- 15. Gene Expression3h 20m
- 16. Regulation of Expression3h 31m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Eukaryotic Post-Translational Regulation13m
- 17. Viruses37m
- 18. Biotechnology2h 58m
- 19. Genomics17m
- 20. Development1h 5m
- 21. Evolution3h 1m
- 22. Evolution of Populations3h 52m
- 23. Speciation1h 37m
- 24. History of Life on Earth2h 6m
- 25. Phylogeny2h 31m
- 26. Prokaryotes4h 59m
- 27. Protists1h 12m
- 28. Plants1h 22m
- 29. Fungi36m
- 30. Overview of Animals34m
- 31. Invertebrates1h 2m
- 32. Vertebrates50m
- 33. Plant Anatomy1h 3m
- 34. Vascular Plant Transport2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System4m
- 44. Animal Reproduction2m
- 45. Nervous System55m
- 46. Sensory Systems46m
- 47. Muscle Systems23m
- 48. Ecology3h 11m
- Introduction to Ecology20m
- Biogeography14m
- Earth's Climate Patterns50m
- Introduction to Terrestrial Biomes10m
- Terrestrial Biomes: Near Equator13m
- Terrestrial Biomes: Temperate Regions10m
- Terrestrial Biomes: Northern Regions15m
- Introduction to Aquatic Biomes27m
- Freshwater Aquatic Biomes14m
- Marine Aquatic Biomes13m
- 49. Animal Behavior28m
- 50. Population Ecology3h 41m
- Introduction to Population Ecology28m
- Population Sampling Methods23m
- Life History12m
- Population Demography17m
- Factors Limiting Population Growth14m
- Introduction to Population Growth Models22m
- Linear Population Growth6m
- Exponential Population Growth29m
- Logistic Population Growth32m
- r/K Selection10m
- The Human Population22m
- 51. Community Ecology2h 46m
- Introduction to Community Ecology2m
- Introduction to Community Interactions9m
- Community Interactions: Competition (-/-)38m
- Community Interactions: Exploitation (+/-)23m
- Community Interactions: Mutualism (+/+) & Commensalism (+/0)9m
- Community Structure35m
- Community Dynamics26m
- Geographic Impact on Communities21m
- 52. Ecosystems2h 36m
- 53. Conservation Biology24m
52. Ecosystems
Introduction to Ecosystems
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