THE FIVE KINGDOMS
Michael Ellis

A couple of months ago an alert listener gently reminded me that I had called a fungus a kind of plant. Yes I did take a shortcut on that piece when I described a lichen as a symbiotic relationship between two plants – an algae and a fungus. Mushrooms are in their own Kingdom – the fungi.

But it wasn’t always this way. When I was a child we were taught there were only two major divisions – Plants and Animals. Plants didn’t move, animals did. Animals grew to a certain size and then stopped. Plants continued to grow through life. That made it easy. The trouble is life does not fit neatly into only two categories. Now there are five kingdoms, at least this week.

Kingdom Animalia. They are multicellular and each cell has a nucleus, they move either by muscles or cilia and they get energy by eating other things. That’s us, ants, and jellyfish.

Kingdom Plantae. They too are multicellular but are stationary. They manufacture their own food through photosynthesis and their growth pattern is affected by their environment. When mature they have a less definite form than animals. They are mostly green.
Kingdom Fungi. Mushrooms, yeast, athlete’s foot, and penicillin are a few examples. They all digest food outside their bodies. These are earth’s best recyclers.

Kingdom Protista. . Amoebas, diatoms, dinoflagellates. All are one celled organisms that may have characteristics of plants (they can make their own food) or those of animals (they ingest food). But they have more in common with each other than differences. They can move by cilia and their cells have a nucleus.

Kingdom Monera. While this group has the smallest number of species at 10,000 they are the most abundant forms of life on earth. They are one-celled with no nucleus. These are the bacteria and blue-green algae. They are the original forms of all life.
Finally viruses are not even part of this classification system because they blur the boundaries between the living and dead but that is for another day.

This is Michael Ellis with a Perspective.

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Posted on

November 7, 2010