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Taxonomy Introduction. Assigning Scientific Names. The first step in understanding and studying diversity is to describe and name each species.
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Assigning Scientific Names • The first step in understanding and studying diversity is to describe and name each species. • By using a scientific name, biologists can be sure that they are discussing the same organism. Common names can be confusing because they vary among languages and from place to place. • For example, the names cougar, puma, panther, and mountain lion can all be used to indicate the same animal— FelisConcolor.
Assigning Scientific Names • In the eighteenth century, European scientists agreed to assign Latin or Greek names to each species. Early scientific names often used long phrases to describe species in great detail. • 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.” • It was also difficult to standardize names because different scientists focused on different characteristics
Binomial Nomenclature • In the 1730s, Swedish botanist Carolus Linnaeus developed a two-word naming system called binomial nomenclature. • The scientific name usually is Latin. It is written in italics. The first word begins with a capital letter, and the second word is lower cased.
Binomial Nomenclature • The polar bear, for example, is called Ursusmaritimus. • The first part of the name—Ursus—is the genus to which the organism belongs. A genus is a group of similar species. The genus Ursuscontains five other species of bears, including Ursusarctos, the brown bear or grizzly bear.
Binomial Nomenclature • The second part of a scientific name—maritimusfor polar bears—is unique to each species and is often a description of the organism’s habitat or of an important trait. The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.
Binomial Nomenclature • The scientific name of the red maple is Acer rubrum. • The genus Acer consists of all maple trees. • The species rubrumdescribes the red maple’s color.
Classifying Species into Larger Groups • In addition to naming organisms, biologists try to organize, or classify, living and fossil species into larger groups that have biological meaning. Biologists often refer to these groups as taxa (singular: taxon). • The science of naming and grouping organisms is called systematics.
Linnaean Classification System • Over time, Linnaeus’s original classification system would expand to include seven hierarchical taxa: species, genus, family, order, class, phylum, and kingdom.
Problems With Traditional Classification • In a way, members of a species determine which organisms belong to that species by deciding with whom they mate and produce fertile offspring. • Ranks above the level of species, however, are determined by researchers who decide how to define and describe genera, families, orders, classes, phyla, and kingdoms. • Linnaeus grouped organisms into larger taxa according to overall similarities and differences. But which similarities and differences are the most important?
Problems With Traditional Classification • For example, adult barnacles and limpets live attached to rocks and have similar-looking shells. • Adult crabs don’t look anything like barnacles and limpets. • Based on these features, one would likely classify limpets and barnacles together and crabs in a different group. However, that would be wrong. • Modern classification schemes look beyond overall similarities and differences and group organisms based on evolutionary relationships and DNA analysis.
5 Kingdom system • Traditionally, 5 kingdoms were recognized: • Anamalia • Plantae • Fungi • Protista • Monera
Domains • Through molecular evidence, scientists now classify all organisms into 3 domains. • Eukarya – nucleated celled organisms • Animalia • Plantae • Fungi • Protista • Bacteria – true bacteria • Archaea – extreme bacteria
Bacteria • Single cell without a nucleus • Have a cell wall, cell membrane, ribosomes, and DNA (not encased in a membrane). • Classified by their shape, cell wall composition, and how they get their nutrition.
Archaea • Extreme bacteria • Live in hot springs, salt lakes, and other harsh environments. • Very different (in cellular processes) that other bacteria.
Protista • Single cells with a nucleus. • Very diverse kingdom. • Includes animal like protists (protozoans), plant like protists (algae), and fungal like protists (slime molds).
Fungi • Multicellular (usually) and sessile (do not move). • Nutrition by absorption • Includes mushrooms, molds, morels, and yeast.
Plantae • Multicellular, sessile, and autotrophic. • Have cell walls made of cellulose. • Have chloroplasts for photosynthesis. • The word “division” is used in place of phyla in plant biology.
Bryophyta • Have no vessels to transport fluids. • Absorb water through entire body (must grow in a moist environment. • No organs • Have thin tubes called rhizoids for anchorage. • Classes include mosses liverworts and hornworts.
Filicophyta • Seedless and vascular • Reproduces using spores. • Ferns are an example.
Coniferophyta • Cone baring plants (seeds are in cones) • Gymnosperms – literally means “naked seed” • The ovule is exposed during fertilization • Needle-like leaves • These dominated the Mesozoic Era.
Anthophyta • Flowering plants • Angiosperms • Dominant plant on Earth today. • Broad Leaves
Ginkophyta • Common in the Jurassic and Cretaceous. • One species remains (Ginko) • Male produces pollen, females produce unprotected ovules.
Animalia • Multicellular • Eukaryotic • Heterotrophic • Usually motile • Often contain specialized tissue such as muscle and nervous tissue.
Animal Bodies • The bodies of most animals (all except sponges) are made up of cells organized into tissues. • Each tissue is specialized to perform specific functions. • In most animals, tissues are organized into even more specialized organs.
Animal Numbers • It is estimated that somewhere around 9 or 10 million species of animals inhabit the earth. • About 800,000 species have been identified. • These have been grouped into 36 separate phyla in the animal kingdom.
Porifera • Contain numerous holes called pores • Lack tissues that many other animals have • Filter feeders • Excretion and respiration are taken care of by each individual cell • Reproduce by budding (asexual) and can regenerate lost parts • Example
Cnidaria • 2 shapes: • cylindrical with tentacles on top (called polyp) • umbrella shaped structure with tentacles on bottom (called medusa) • Tentacles have stinging cells that can only be used once (food and protection) • No brain • Examples:
Platyheminthes • Have no true body cavity • Nervous system with small brain • Can reproduce asexually or sexually (hermaphrodites) • Absorb all materials through individual cells. • Three classes: • Tubellaria (free living flatworms) • Example: • Tremotoda (parasitic flukes) • Cestoda (parasitic tapeworms)
Nematoda • Round worms • One way digestive system (mouth to anus) • Separate sexes • Small circular brain • Examples:
Mollusca • Soft, unsegmented body • Body covered with thin layer called mantle which may secrete a shell • Three body parts: • Head • Foot • Viceral Hump (contains the internal organs) • Gas exchange through gills • Classes • Gastropoda • Pelycepoda (Bivalvia) • Cephalopoda
Annelida • Segmented worms • True body cavity • Well developed digestive tract • Hermaphorditic (sexually reproducing) • Breath through moist skin • Classes • Polychaeta – sand worm • Oligochaeta – earthworm • Hiridinea – leeches
Arthropoda • Jointed appendages • Exoskeleton usually made of chitin • Well developed sense organs (compound eye etc.) • No blood vessels (blood circulated in chambers called sinuses) • Variety of respiratory organs (lungs, trachea, gills)
