HOW MANY KINGDOMS ARE THERE?

by Grandpa Cliff     Dec 28, 2005

Even thousands of years ago, people could tell that there were many different kinds of animals and plants.  Nobody could confuse a bear with a mouse, or a palm tree with a tomato plant.  All Black Bears in the U.S. make up a single species, separate from other bear species like the Grizzly Bear, the Polar Bear, and the Alaskan Brown Bear.  

Species   - a unique kind of living thing which in nature interbreeds only with other living things of the same kind

Organism   - an individual living creature [examples would be your mother, a rose bush, and your best friend]

Classification   - arranging organisms into groups on the basis of their evolutionary relationships

Are Collies, Dalmations, Terriers and Greyhounds separate species, or are they all dogs?  Asked that way, you realize that they are all dogs, and so they must be all the same species even though they look diferent. 

Carolus Linnaeus (cuh-ROE-lus  li-NEE-us) was born 1707 in Sweden.   From a very early age, he developed a deep love of plants and a fascination with their names.  In medical college, he collected

and studied plants.  This was not unusual since every doctor had to prepare and prescribe drugs derived from medicinal plants.  He also studied plants in other countries in Europe, and while in the Netherlands in 1735 he published a book describing his system of grouping related plants together using binomial nomenclature.  Bi- means two, and nom- means name.  So, binomial nomenclature means "two-name naming".  

A scientific name consists of the Genus (always capitalized) and the species name (almost always lower case).  In 1758, as Linnaeus expanded his system of naming to include animals, he named the dog Canis familiaris, the domesticated cat Felis catus, and man Homo sapiens.  Today, the dog is considered to be a subspecies of gray wolf, Canis lupus.  Scientifically, it is known as Canis lupus familiaris.  The third word is the subspecies name (sub means below; submarine means "below the sea".)

Linnaeus lived and worked in Europe which is composed of small countries the size of states in the U.S.  Almost every country has a different language.  So that European scientists could communicate with each, they all learned Latin.  Scientific names of plants and animals were most often chosen from Latin words.

HOW MANY KINGDOMS ARE THERE?

When I began teaching biology in 1962, there were only the two kingdoms of Plantae and Animalia.  A well-respected scientist told me that same year that he believed there were at least five kingdoms, but probably seven.  As the quality of microscopes improved, and chemical techniques for studying the parts of a cell got better, it became obvious that there were more than two kingdoms, and probably more than seven.  To make things simple and useful, I'll discuss five major kingdoms.  However, if your science teacher disagrees with the kingdoms mentioned below, learn what you are taught in school instead of what I have written below. 

In actual fact, there may be as many as 60 kingdoms.  It all depends on whose opinion you read.  This is an area of science on which there is little agreement today.  Fortunately, the extra kingdoms almost all consist of microscopic organisms you will not study or hear of before getting to college.  

GROUPING LIVING THINGS INTO 5 KINGDOMS 

• Plantae :  Plants are multicellular organisms that use chlorophyll to make their own food during the process of photosynthesis.  They cannot move from place to place.  Around the cell membrane plant cells have a cell wall made of cellulose.  Reproduction is by seeds or spores.

• Animalia :  Animals are multicellular organisms which lack chlorophyll and must eat other organisms to survive.  The adult animal can usually move from place to place (sponges and corals are two exceptions).  Animal cells lack a cell wall around the cell membrane.

• Fungi :  Fungi are multicellular organisms which cannot make their own food, because they lack chlorophyll.  They get it from either dead or living organisms.  Fungi cannot move from place to place.  Surrounding the cell membrane is a cell wall made of chitin or cellulose.  Reproduction is by spores.  Fungi, the plural of fungus, is pronounced FUN-gi (-gi as in the word giant).   Examples of fungi are mushrooms, toadstools (really a mushroom), puffballs, molds, mildews and rusts.   

• Monera :  These are bacteria.  They are primarily unicellular (single celled) with a cell wall around the cell membrane.  The cell wall is different from that of plants or fungi.  Monera includes blue-green bacteria (also called cyanobacteria, formerly known as blue-green algae).  Bacteria have no true nucleus, because their nuclear material does not have a membrane around it.  Bacteria is the plural of bacterium.

• Protista :  Some protists are single-celled and ‘animal-like’ such as the amoebas, while others are ‘plant-like’ such as the euglenas which have chlorophyll and can make their own food.  Both of these were once called protozoans.  Algae are also placed in this kingdom.  Protists have a nucleus.  They can be unicellular (one-celled) or multicellular (many-celled).

     If Protista contains every living thing not in the other four kingdoms, it becomes clear that the protists contain groups that are not related to each other, and that must belong in several different kingdoms.  

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STRANGE THINGS

Lichens are very unusual because they are composed of TWO kinds of organisms (an alga and a fungus) living together.  Living inside the fungus are a large number of single-celled algae.  The fungus provides water and protection for the algae which make the food needed by the fungus.  Lichens cannot be placed in a single kingdom.  [The lichen at the right is probably about 1 inch high.]

Viruses are microscopic, and are not alive in the usual sense.  They do reproduce, but not on their own.  They force infected cells to make copies of them.  If they are alive, they would have to be put in a kingdom all their own.