--- title: "Toxins in Food Chains and Organisms Changing Habitats" description: "Explain bioaccumulation within organisms, biomagnification of some pollutants through food chains, and ways organisms change their habitats" canonical: https://lightmysky.com/learn/science/toxins-in-food-chains-and-organisms-changing-habitats-mt_YvCgDM0Scg source: https://lightmysky.com/learn/science/toxins-in-food-chains-and-organisms-changing-habitats-mt_YvCgDM0Scg.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Toxins in Food Chains and Organisms Changing Habitats Explain bioaccumulation within organisms, biomagnification of some pollutants through food chains, and ways organisms change their habitats Subject: Science · Area: Ecosystems & Habitats · Ages 12 to 13 Page: https://lightmysky.com/learn/science/toxins-in-food-chains-and-organisms-changing-habitats-mt_YvCgDM0Scg ## Ready when they can - Distinguishes bioaccumulation within an organism from biomagnification, an increase in pollutant concentration across feeding levels - Gives a real example of pollutant build-up, such as DDT-related effects in peregrine falcons or mercury in predatory fish - Explains how organisms can change their habitat (e.g. earthworms aerating soil, beavers creating wetlands) - Explains why top predators can receive high concentrations of pollutants that persist and biomagnify, while recognizing that harm also depends on sensitivity ## Lesson: Pollutants and Habitat Change Food webs connect organisms through feeding. Harmful substances can enter a body from food, water or other surroundings. Bioaccumulation is build-up within an organism over time when a substance enters faster than the organism removes it. Some pollutants remain in bodies for a long time. Others break down or leave quickly, so taking in a substance does not always mean it accumulates. Biomagnification means a pollutant's concentration increases across feeding levels. Concentration is the amount per gram of tissue. Predators eat contaminated prey and may retain substances that leave slowly. Some persistent pollutants can reach high concentrations in top predators. This does not happen with every substance. Rapid breakdown or removal can prevent build-up. Harm also depends on an organism's sensitivity. *(drawing: Invented concentrations: 1, 4 and 12 units per gram of tissue. The chart models biomagnification; it is not measured food-chain data.)* **Example.** DDT was used as a pesticide. It reached peregrine falcons through contaminated birds they ate. DDT and its breakdown product DDE could build up in the falcons. DDE disrupted eggshell formation, producing thinner shells. More eggs broke during nesting, so fewer chicks hatched. This contributed to peregrine population declines. Peregrines mainly eat birds, not fish. Total amount is different from concentration. A large animal can contain more toxin in total without having more per gram of tissue. For a model calculation, state the starting amount and how much is retained. A fish starting with zero units and keeping all the toxin from 3 prey with 8 units each gains 3 × 8 = 24 units. Real animals may remove some of a substance. *(drawing: Each row represents one prey dose of 8 toxin units. With complete retention, 3 × 8 gives 24 units in total, not a concentration.)* Organisms also change habitats. Earthworm tunnels can help air and water move through soil. Beaver dams slow flowing water and can flood nearby land, creating ponds and wetlands. Some wetland species gain suitable habitat, while species needing the flooded land may lose habitat. The same physical change can therefore have different effects on different organisms. Build-up depends on intake, breakdown and removal. Rapid removal can prevent build-up despite repeated meals. Sensitivity means how strongly an organism is affected by a substance. A lower concentration can harm a more sensitive organism more than a higher concentration harms a less sensitive one. Feeding level or concentration alone cannot show which species suffers most. **Recap.** Bioaccumulation is build-up within an organism. Some pollutants biomagnify across feeding levels. Organisms also change habitats, with different effects on different species. *Lesson revisions, questions and flashcard revisions written for this dataset. Numerical charts and complete-retention calculations are teaching models, not measured food-chain data.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Food Webs & Interdependence](https://lightmysky.com/learn/science/food-webs-and-interdependence-mt_URTJbS3hhs) ## Opens up - [Biodiversity & Resilience](https://lightmysky.com/learn/science/biodiversity-and-resilience-mt_xSs0xAd6i1)