Classification
Classification is a way of life….
Evolution has created great diversity of life More than 2.5 million different kinds of organisms have been identified. It is estimated that as many as 20 million more may be discovered.
Naming and grouping these organisms helps us see relationships.
Features of a good classification system: 1. Needs to use universally accepted names for organisms 2. Doesn’t use common names--they can be misleading and confusing. Mountain lion, cougar, puma, panther-same animal Starfish, jellyfish, seahorse, groundhog
Organisms should be placed in groups that share important traits and show evolutionary relationships The plant and the worm share few common traits and are far apart in their evolutionary history.
The science of naming and grouping organisms is called systematics. it’s goal is to organize things with meaning.
Early Classification Systems: Aristotle-grouped animals by how they moved (fly, swim, walk). Even though it had obvious problems, his system was used for nearly 2000 years.
18th century scientists began to use Latin names but they were overly long (20 words or more) For example, the English translation of the scientific name of a tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.”
The Linnaean System Carl Linnaeus was a Swedish Botanist; he developed the system for giving things two names. His method is called binomial nomenclature
Each organism gets a first and last name. -the first name is the genus. It is a small group of very similar organisms. -the second name is the species. These are all the same organism Definition of a species: members of the same species can interbreed and have fertile offspring.
Examples: All dogs are the same species because they can interbreed and have fertile offspring.
Horses and donkeys are not the same species because their offspring, a mule, is sterile.
Example: Acer rubrum-red maple Acer palmatum-palm maple
Example: Felis leo Felis tigris
How to write a scientific name: The genus name is always capitalized, species is always small. It must then be underlined or italicized to be set apart. Names are in Latin so the meanings won’t change with use.
Examples: Ursus arctos horrible “horrible artic bear” for the grizzly bear
Ursus maritimus Polar bear Ursus americanus Black bear
Some are named for a location: Microtus pennsylvanicus Sphiggurus mexicanus
Atlantic Puffin Fratercula arctica translates as “little brother of the Arctic”),
Some are named for people: Beyonce: Scaptia beyonceae
Barack Obama: Caloplaca obamae
7 Categories: Kingdom Phylum Class Order Family Genus Species
Use a sentence to remember the order: Kathy Kings Puts Play Cheese Chess On On Fresh Fine Garden Grain Salad Sand
Examples: Human Housecat animalia chordata mammalia primate homididae Homo sapien Housecat animalia chordata mammalia carnivora felididae Felis domesticus
Categories go from general to specific Animal Chordata Mammalia Carnivora Ursidae Ursus artic horribilus
Modern Classification methods: In the 1970s a new level was added. Kingdoms were grouped into domains.
Today the following are often looked at to classify new organisms: 1. homologous structures 2. embryos 3. fossils 4. biochemicals a. DNA b. RNA c. Proteins like Cytochrome c (found in all living things)
Kingdoms: Linnaeus started with 2 kingdoms: plants and animals. It became clear that not everything fit into those 2 kingdoms so more were added.
There are now 6 kingdoms: 1. Eubacteria—these are the most common bacteria. (“eu” means “true”) Bacteria are all prokaryotic and unicellular. They are the smallest cells that exist.
2. Archaebacteria—this is the newest kingdom 2. Archaebacteria—this is the newest kingdom. These bacteria have different cell walls, lipids and ribosomes. They are all prokaryotic and unicellular. They like extreme places to live.
3. Protista—all have large eukaryotic cells 3. Protista—all have large eukaryotic cells. They may be unicellular or multicellular. They may be autotrophic or heterotrophic. They don’t fit anywhere else.
4. Fungi--eukaryotic, heterotrophic, with cell walls 4. Fungi--eukaryotic, heterotrophic, with cell walls. However the cell walls are different from plants.
5. Plantae—all are eukaryotic, multicellular, have cell walls made of cellulose, and are autotrophic.
6. Animalia—all are eukaryotic, multicellular, have no cell walls, and are heterotrophic.
How the kingdoms fit into domains: Domain Bacteria – Kingdom Eubacteria Domain Archaea – Kingdom Archaebacteria Domain Eukarya – Kingdoms Protista, Fungi, Plantae, Animalia