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Biological Magnification

The Food Chain

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DDT in the Food Chain

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DDT in the Food Chain

When DDT was sprayed on farm crops, some of it ended up in nearby streams, rivers and oceans. Tiny ocean organisms called plankton got contaminated or polluted with DDT. When shellfish ate the plankton, the shellfish became contaminated too. Bigger fish would eat the shellfish and seals would eat the bigger fish. These sea creatures also became contaminated. When a killer whale ate the seal, it too got poisoned. By the time the DDT had gotten into the killer whale however, it was millions of times stronger than when it first contaminated the plankton. This is because toxins like DDT can get stored and build up or accumulate in the fat or fatty tissue of animals. When animals eat other animals, they're also ingesting the toxins stored in their prey's fat. For example, if in one day a little fish eats 1,000 plankton and a whale eats 1,000 little fish, the whale is ingesting all the toxins that were in a million plankton! (1,000 x 1,000 = 1,000,000.)