Classification: Kingdoms (Part 2)

Reproduction

>Taxonomists use the type of reproduction to classify organisms as well. There are two types of reproduction: sexual and asexual. Asexual reproduction does not require a male and female. Mitosis is the process underlying it. Organisms that undergo asexual reproduction have been placed in the kingdoms of Eubacteria and Archaebacteria. >Sexual reproduction, however, involves the union of male and female gametes. Meiosis is the first process, in which the gametes are formed, each with half of the total chromosomes required. This is followed by fertilization, where the correct number of chromosomes is restored. Then, mitosis begins forming new cells, each with the same number of chromosomes. >Organisms relying solely on sexual reproduction have been placed in kingdom Animalia. >Organisms that rely on both sexual and asexual forms of reproduction are placed in the kingdoms Plantae, Protista, and Fungi.

Life

A category that includes all entities that have self-sustaining processes within them.

Kingdom: Eubacteria

All bacteria used to belong to one kingdom, but they have since been broken into two. Eubacteria are mostly single-celled prokaryotes that lack a nucleus as well as some other organelles. They are single-celled organisms that have a long lash-like appendage called a flagellum used for locomotion. They are present in all environments and can be helpful or harmful. Eubacteria that help the production of yogurt are useful, while the ones that can give you strep throat are literally a pain in the neck.

Three Main Domains

All organisms that are alive and share basic molecular similarities which are bacteria, archaea, and eukarya. Organisms of the three domains have basic molecular similarities, like the presence of DNA and plasma membranes. These similarities are believed to exist because of a common ancestor. However, important differences exist among the three domains. These differences occur mainly because of the way the cells are developed. (The three domains of life have been further classified into six kingdoms, each with distinctive characteristics and features.)

Mode of Nutrition

An organism can be classified into a kingdom based on its mode of nutrition. For example, all organisms that produce their own food are called autotrophs. All organisms that eat plants or other rely on other organisms for food fall into the category of heterotrophs. Some Eubacteria, Protista, and Archaebacteria fall into both categories. Animals are clearly heterotrophic, while plants are the only true autotrophs. Plants create their own food using chlorophyll and the process of photosynthesis.

Motility

Another characteristic that can be helpful in classification is motility, or the ability to move. Organisms belonging to the kingdom Animalia move and are called motile. Organisms that belong to the kingdoms Plantae and Archaebacteria do not move and are called non-motile or sessile. Eubacteria can move using a whip-like structure called flagella, and other microorganisms belonging to the kingdom Protista can move if they possess a flagella or hairy structures called cilia.

Kingdom: Archaebacteria

Archaebacteria are extreme bacteria. They are bacteria that can survive in harsh environments, like the hot spring shown here, or where there is no oxygen. They are considered anaerobic (without oxygen) bacteria. These bacteria love hot temperatures and can be found in the hot springs of Yellowstone National Park. Some love salt environments and can be found in the Utah salt lakes or the Dead Sea in Israel. They can even be found in deep sea thermal vents that spew out sulfuric acid.

Kingdom: Fungi

Fungi look like plants as they sprout from the ground; however, they cannot carry out photosynthesis or make their own food. They are dependent on dead and decaying matter on the ground and live off other plants. Examples include mildew, mushrooms, and the mold shown in the image.

Kingdom Interactions

Organisms in every kingdom interact with each other and often need each other for their survival. These relationships are an intricate part of the survival of all creatures, especially on a farm. In the video below you will visit a farm to find out how organisms from all the six kingdoms of life co-exist and survive.

Kingdom: Protista

Protista are all unicellular organisms that do not belong to the category of Bacteria, Archaebacterial, or Fungi. Protista, also called protists, are complex but unicellular, which separates them from other more simple unicellular organisms. Classic examples include the red algae in the sea and the slime mold and green algae in ponds and other wet areas.

Cell Organization

Scientists also look to see how the cells are organized. If the organism has many cells and the cells are organized into tissues and organs then it's a multicellular (many cells) organism. The absence of such organization shows it's a unicellular (single cell) organism. Multicelluar organisms are placed in Plantae, Animalia, or Fungi, while organisms that are unicellular are placed in Eubacteria, Protista, or Archaebacteria.

Cell Types

Scientists study the cells of each organism under a microscope and look for the presence of organized organelles such as a nucleus. The presence of organelles indicates that the organism is a eukaryote. Without organelles, the cell is a prokaryote. Organisms possessing prokaryotic cells are placed in the eubacteria or archaebacteria kingdoms, while organisms possessing eukaryotic cells are placed in one of the other four.

Kingdom: Plantae

There are over 25,000 species of plants on earth. This kingdom contains multicellular organisms including flowering and non-flowering plants. These "lungs on earth" regulate the amount of oxygen on earth through photosynthesis using a green pigment called chlorophyll. From the lowly green grass on the ground to the giant sequoia trees of California, plants are also a dominant presence on earth.

Kingdom: Animalia

There are more than one million species of animals on earth. Some have backbones (vertebrates) and some do not (invertebrates). They inhabit all kinds of environments and are a dominant group of life on earth. They are multicellular and have sophisticated organ systems. Examples include insects, birds, whales, reptiles, sponges, and elephants.