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nHavenyou ever seen a diagram that shows a pyramid of living things in annecosystem? There has to be a whole lot of grass to feed angrasshopper, a whole lot of grasshoppers to feed a rat, a whole lotnof rats to feed a snake, and a whole lot of snakes to feed a hawk.
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nItnreminds me of a children’s story! (“This is the cat that ate thenrat that ate the malt that lay in the house that Jack built…”)
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nThisnfood chain of grass → grasshopper → rat → snake → hawk isnoversimplified, since each of the consumers eats other things asnwell. However, the point is that the numbers of organisms at eachnhigher level of the food chain tend to get smaller. That’s why we cannrepresent such food chains as pyramids.
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nThenecological “pyramid of numbers” was first presented by today’snbirthday boy, English scientist Charles Elton. He was born on thisndate in 1900, and he did several studies on Arctic ecosystems.
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nAsidenfrom the pyramid of numbers, Elton described ecological niches andnstudied what happens to an ecosystem when an invasive species isnintroduced. Here are some websites to help you explore Elton’s ideas:
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nHeren is a nice website on food chains. Notice the diagram of ann ecological pyramid.
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nBBC’s Bitesize offers more pyramid diagrams.
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nHappenin’ Habitats features a habitat web activity.
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Ann ecological niche is kind of like a job or role that a plant orn animal does within a particular habitat. For example, in the coastaln waters of Washington state, I got to see a pod of dolphins that fitn in the niche of feeding on smaller porpoises and seals, and later In saw another pod of dolphins that fit in the niche of feeding onn salmon. Because the two different pods eat different things, theyn behave in different ways; their hunting patterns are different, andn the mammal-eaters are always on the move, while the fish-eatersn pretty much stay in one place. It’s like comparing two groups ofn humans, deer-hunters and wheat-growers. Other creatures who live inn the same coastal waters include Dungeness crabs, which eat clams andn small fish but which freelance as scavengers, eating bits of “trash”n and debris—dead bodies and body parts that would mess up then habitat if there were no scavengers. Gulls also eat small fish andn act as scavengers, but they feed in deeper water than do crabs.n
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nHeren and also here are additional explanations of ecological niches.n
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nNational Geographic Kids tells us about plant invaders.
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nAlsonon this date:
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nMemorial Day in Madagascar
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nAnniversary of the day the Niagara Falls stopped falling
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