With Douglas Drenkow

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The Diversity of

The World of Life

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The Diversity of The World of Life

Listings & Biology for Hundreds of Species, Families, & Higher Groups of Life, with Links to Webpages with Excellent Photos & Additional Information Elsewhere on the Internet

Note that you may use the "Search" feature (at left on every webpage) to quickly find references within this site to any specific species etc. [Note: Since I migrated this site from AT&T Worldnet to Earthlink, the Search feature is no longer functional.] Otherwise, follow the links below and throughout this section, to systematically explore the wondrous diversity of the world of life.

Please note that even with the great diversity presented, this website has omitted many of the less well known groups of life and almost all of those of species that have become extinct.

I hope to continually increase the breadth and depth of information within this section, as with essays on Featured Topics.

As you will note, this section also serves as an "internet directory", presenting links to many other websites from around the world, with photos and other valuable information.  I particularly recommend certain excellent on-line references (and I also strongly advise you to read a word about linking).  You may always return to this site by simply closing the window that opens when you click on any of those links.

To Explore the Diversity of The World of Life,

Please Click Here.

To Read About the Science of Making these "Family Trees",

Please Read On...

"Systematics":

The Classification of

The World of Life

There are well over a million known species of living organisms in the world and undoubtedly many more as yet undiscovered, particularly in the ever-shrinking Tropical rain forests or the unfathomable depths of the seas.

It is in the nature of Homo sapiens or any other intelligent species to try to find out how the members of any group of things are alike and yet different.  Although all of us may be alike in that concern, we each differ in our point of view.  Biologists are human, too (!); so it is not surprising that there are different systems of classifying and, thus, naming species of living things.

"Systematics" is the systematic studying of those traits -- from the largest features of anatomy to the smallest mutations in genes -- that various species do or do not have in common, in order to define "taxa", named groups in general, and "clades" (rhymes with "glades"), categories not only named but also based upon the natural relationships between species -- evidence (to most biologists) of common ancestors in evolution.

Different "taxonomists" devise different systems of classification, each of which usually accounts for most but not all of the variations between species; and as knowledge grows (particularly in biochemistry and genetics), these schemes inevitably change.

However, it is worth remembering that what does not change -- at least over time frames too short for natural selection to significantly change populations, by survival of the fittest -- are the species themselves -- the fundamental, natural groups of living things (typically defined as a population of organisms that can at least theoretically successfully breed with one another and produce fertile offspring).  Species -- and arguably only species -- do naturally exist, regardless of how we choose to artificially group them (or customarily divide them, as into "subspecies", "varieties", or "races").

Even at the most basic level -- the highest taxa of classification -- there is considerable disagreement.

Traditionally, there was the "Two Kingdom" system:  Every species was classified as either a plant or an animal.  A plant was characterized by being typically immobile, with a typically rigid wall around the one to many cells in its body, and producing its own food molecules, typically by photosynthesis (with energy typically from sunlight) but sometimes by chemosynthesis (with energy from minerals etc.).  An animal was characterized by being typically mobile, with no wall around the one to many cells in its body, and consuming other organisms or their products as food.

Then there was the "Three Kingdom" system.  Plants were divided into "Prokaryotes" (bacteria and other cells without a "nucleus" for their genetic material, typically DNA) and "Higher Plants" (whose cells, like those of all animals, have their genetic material housed within a membrane-bound nucleus).

Then there was the "Five Kingdom" system:  "Monera" (bacteria and other prokaryotes, namely blue-green algae), "Protista" (various algae, fungus-like "slime molds", and "protozoans" -- single-celled animals), Fungi, Plants, and Animals.

Today, the concept of a "kingdom" has been mostly abandoned.  Genetic research has identified three "domains", major groups of life whose members are more alike one another than like those of the other groups:  "Archaea" (those prokaryotes, previously classified as bacteria, that typically thrive under extreme conditions, as of temperature and acidity, as were prevalent in the earliest days on Earth) -- presumably the first forms of life on Earth -- as well as Bacteria and "Eukaryotes" (organisms whose cells do have a nucleus).

The Eukaryotes are divided into several major groups plus dozens of other lineages of "protists" (mostly microscopic, single-celled amoebas and flagellates) whose relationships to one another are not yet clear.  The major groups of Eukaryotes that have been defined are "alveolates" (including the familiar Paramecium as well as the organism that causes malaria and various other protists), "stramenopiles" (water molds, diatoms, and various algae), red algae (a collection of certain seaweeds etc., now appreciated as a major group in its own right), green plants (including green algae and all land plants), fungi, "collar flagellates" (single-celled organisms very reminiscent of the "collar cells" of sponges, the most primitive animals), and animals (all multi-cellular).

To learn more about these major groups of life and hundreds of their specific members...Please Click Here.

Doug@DouglasDrenkow.com

(c) 2004 D.D.  All Rights Reserved.

Photo of Cells:  H.D.A. Lindquist, US EPA