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The Diversity of Life
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Aristotle: about 2,300 years BP
The First Classifiers... Aristotle: about 2,300 years BP Plants and animals, habitats and physical differences Carolus Linnaeus: in the late 1700s The system we have today, with the kingdoms Linnaeus classified organisms not just by structural similarities and differences, but by evolutionary relationships.
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The true total number of species is estimated between: 1.4 million
We are unsure of the true number of species on Earth, but up to now scientists have classified: The true total number of species is estimated between: 1.4 million 2-100 million In the Linnaean system, kingdoms are the largest taxon, or grouping of organisms. However, recently scientists have described yet a larger taxon. There are three domains, into which scientists have grouped all living things: Archaea Prokaryotes Eubacteria Eukaryotes Eukarya
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Classification The science of classification is known as TAXONOMY. Taxonomic nomenclature is a fancy way of saying “our scientific system of naming orgainsms”. Binomial nomenclature is the part of taxonomic nomenclature that contains the final two classifications…that of Genus, and species. Binomial nomenclature is the most common two name system known to science. What is the binomial nomenclature of humans? ANS: Homo sapiens Domain: Eukarya Kingdom: Animalia Phylum: Chordata Class: Mammalia TAXONOMIC NOMENCLATURE OF HUMANS: Order: Primates Family: Hominidae Homo Genus: Species: sapiens
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Classification of Living Things
Taxonomy, the classification of organisms according to similarity, has been influenced by phylogenetics. Classification of Living Things DOMAIN Bacteria Archaea Eukarya KINGDOM Eubacteria Archaebacteria Protista Fungi Plantae Animalia CELL TYPE Prokaryote Eukaryote CELL STRUCTURES Cell walls with peptidoglycan Cell walls without peptidoglycan Cell walls of cellulose in some; some have chloroplasts Cell walls of chitin Cell walls of cellulose; chloroplasts No cell walls or chloroplasts NUMBER OF CELLS Unicellular Most unicellular; some colonial; some multicellular Most multicellular; some unicellular Multicellular MODE OF NUTRITION Autotroph or heterotroph Heterotroph Autotroph EXAMPLES Streptococcus, Escherichia coli Methanogens, halophiles Amoeba, Paramecium, slime molds, giant kelp Mushrooms, yeasts Mosses, ferns, flowering plants Sponges, worms, insects, fishes, mammals
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Classification of Four Organisms
Corn Whale Shark Humpback Spider Monkey Kingdom Plantae Animalia Phylum Anthophyta Chordata Class Monocotyledones Chondrichthyes Mammalia Order Commelinales Squaliformes Cetacea Primates Family Poaceae Rhincodontidae Balaenopteridae Atelidae Genus Zea Rhincodon Megaptera Ateles Species Zea mays Rhinacodon typus Megaptera novaeangilae Ateles paniscus Eukarya Pay close attention to this taxonomic table, because the activity designed for later, and tomorrow will have you designing one of your own. You can tell simply by looking at this taxonomic table, which organisms are more closely related by observing their similarities. The more they have in common…the more related they are. Which two organisms are most closely related? To what domain would all these organisms belong?
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until finally, you arrive at the species, and there is only one!
Notice that as you move down through the “taxons”, you see more and more specificity, and fewer and fewer organisms… until finally, you arrive at the species, and there is only one! Into what domain would plants fit? Eukarya
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The Six Kingdoms of Life
Archaebacteria Monerans Eubacteria Protista Algae, protozoans, and slime molds Fungi Mushrooms, molds, yeasts and lichens Plantae Plants Animalia Animals
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Kingdom: Archaebacteria
There are only a couple hundred species of archaebacteria that have been classified on Earth, and most of them live in extreme environments. An extremophile is an organism that thrives under "extreme" conditions, such as: All archaebacteria are unicellular prokaryotes, and lack distinct membrane bound organelles… but unlike Eubacteria, Archaebacteria do not have peptidoglycan in their cell walls. low or high pH high salt concentration high temperatures low temperatures Autotrophs Heterotrophs Chemotrophs Interestingly, archaebacteria have complex genetic makeup, and their genes have similar structure to those found in eukaryotes (far more complex organisms). Questions have been raised about which came first, as a result!
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Kingdom: Eubacteria Just as the archaebacteria, Eubacteria are all unicellular prokaryotes…but some live in colonial fashion. There are 10,000 described species. They have extremely strong cell walls, no defined nucleus or membrane bound organelles, and a less complex genetic makeup than found in archaebacteria and eukaryotes. While some Eubacteria are known to cause diseases, such as strep throat and pneumonia, most are harmless and indeed are actually helpful, like Lactobacillus acidophilus
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Kingdom: Protista Kingdom Protista is hugely diverse (250,000 species). While most are unicellular, some are multicellular, but they all share some common characteristics. Protists are eukaryotes that lack complex organ systems and live in moist environments. Some are animal-like heterotrophs Some are plant-like autotrophs Still others are fungi-like heterotrophs With the diversity of this kingdom in mind, many scientists believe it should be divided to make it more manageable.
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Kingdom: Fungi Organisms in Kingdom Fungi are heterotrophs that do not move from place to place. They can be either unicellular or multicellular eukaryotes that absorb nutrients from organic materials in the environment. There are more than 50,000 known species of fungi, and they are all decomposers. Stinkhorn fly agarics mushroom Puffball Yeast
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Most fungi are decomposers, and they digest things extracellularly, and then absorb the nutrients through a network of “root-like” structures known as hyphae. Sometimes the fungus doesn't wait for the organism to die, in which case the fungus is called a parasite. Another thing that sets fungi apart from plants and other organisms with cell walls, is the presence of chitin. Chitin is a polysaccharide that is beneficial as a structural strengthener in the fungi organism.
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Kingdom: Plantae All plants are multicellular autotrophic eukaryotes.
Plants are sessile. Cells usually contain chloroplasts to help in the production of sugars during photosynthesis. Cell walls which contain cellulose. Plant “bodies” are organized from cells, to tissues, to organs, to organ systems. There are more than 250,000 species of plants described on Earth today. While the more familiar flowering plants exist, don’t forget about the lowly mosses, ferns and evergreens
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Kingdom: Animalia Like plants, all animals are multicellular. Unlike plants, however, all animals are heterotrophs. Nearly all of them move from place to place Animal cells do not contain cell walls, or chloroplasts Animal “bodies” are organized into cells, tissues, organs and organ systems. There are an amazing 1,000,000 species of described animals on Earth. Animals range from the most simple invertebrate sponge, to the most complex vertebrate mammal.
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The Simple Invertebrates
Kingdom: Animalia The Simple Invertebrates Rotifera Mollusks Annelids Nematoda Porifera Cnidarians Platyhelminthes
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The Complex Invertebrates
Kingdom: Animalia The Complex Invertebrates Arthropods Echinoderms
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Simple Vertebrates: Fish and Amphibians
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Vertebrates: The Reptiles, Birds, and Mammals
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Classification of Four Organisms
Hopefully, this table looks familiar to you! Each lab group will get a random list of 10 organisms to classify based upon their taxonomic nomenclature. Students will research each of these organisms, and place them in a classification table such as this. Based upon their classification, students will then decide which two are most closely related, and which two (or more) are most distantly related. They will justify that relationship with data they found while researching. Classification of Four Organisms Corn Whale Shark Humpback Spider Monkey Kingdom Plantae Animalia Phylum Anthophyta Chordata Class Monocotyledones Chondrichthyes Mammalia Order Commelinales Squaliformes Cetacea Primates Family Poaceae Rhincodontidae Balaenopteridae Atelidae Genus Zea Rhincodon Megaptera Ateles Species Zea mays Rhinacodon typus Megaptera novaeangilae Ateles paniscus Then, students will draw and color these four organisms for placement on their posters. Have some fun with this! The humpback whale and the spider monkey diverge at the order taxon. This makes them the most closely related of all four. The three animals are most distantly related to the plant at the kingdom taxon.
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