Classification "The incredible diversity of life on this planet, most of which is microbial, can only be understood in an evolutionary framework" -- Carl Woese, 2000

What is Taxonomy?  How do we keep track of the some 1.7 million species of living organisms have been discovered?  Taxonomy is the science dealing with the description, identification, naming, and classification of organisms

Carolus Linnaeus  The classification system used today was developed Swedish botanist Linnaeus in the 1700s.  Linnaeus used structural similarities as the basis of his classification system.

Binomial Nomenclature  In order to identify organisms by a universal name, Linnaeus devising a two name system in which an organism is identified by its genus and species.  For example, Homo sapiens is the scientific name for man. The genus is capitalized and the species, sapiens, is lower case.  The scientific name of an organism is always italicized organism is always italicized or underlined. or underlined.

Five Kingdom Classification System  The five kingdoms, from simplest to most complex are: --Monera (bacteria) --Protista --Fungi --Plantae --Animalia

Criteria for Classification Kingdom Classification:  Does the organism have an organized nucleus?  Is the organism unicellular or multicellular?  How does the organism obtain its food (autotroph or heterotroph)? Further Classification:  Common ancestry  Homologous structures  Comparative biochemistry  Fossil record  Comparative embryology

Terminology  Prokaryote --does not have an organized nucleus --does not have an organized nucleus --genetic material is dispersed in the cytoplasm --genetic material is dispersed in the cytoplasm --lacks most other organelles --lacks most other organelles  Eukaryote --has a membrane bound nucleus --has a membrane bound nucleus --has membrane bound organelles --has membrane bound organelles

New Discoveries  In the 1970s, scientists began to find evidence of an unknown group of microbes that existed in extreme environments.  These organisms were found in deep sea hydrothermal vents, hot springs, acid lakes, and very salty environments.  Because these microbes were thought to be prokaryotic, they were called archaebacteria (ancient bacteria)  Using DNA analysis and other biochemical characteristics that these bacteria were more closely related to eukaryotes than to modern bacteria and are now officially called Archaea.

The Three Domains By the 1990s, scientists recognized that there were three distinctly different lineages that accurately describe the relationships among living organisms.  By the 1990s, scientists recognized that there were three distinctly different lineages that accurately describe the relationships among living organisms. The super kingdoms or domains include the Archaens, the Protist, Fungi, Plant, and Animal kingdoms, and divide the Moneran kingdom between the Archaens and Bacteria domains  The super kingdoms or domains include the Archaens, the Protist, Fungi, Plant, and Animal kingdoms, and divide the Moneran kingdom between the Archaens and Bacteria domains.

Archaea  Methanogens: chemosynthetic (make their own food using inorganic molecules) releasing methane gas. Live in swamps, marshes, guts of cattle and termites.  Halophiles: live in very salty environments such as the Dead Sea, the Great Salt lake or salt evaporation ponds.  Thermophiles: live in hot sulfur springs, deep sea hydrothermal vents, in ocean waters around Antarctica, and under the polar ice caps.

Characteristics of Prokaryotes Archaea  No nucleus  Ability to live in extreme environments  Cell wall and cell membrane  DNA in ringlike structure in cytoplasm  DNA/RNA more similar to eukaryotes  Few organelles Bacteria  No nucleus  DNA loop in cytoplasm  Cell wall and cell membrane  Few organelles  Have flagella for locomotion

Eukarya  Includes Protists, Fungi, Plants, and Animals  membrane bound nucleus  Organelles to carry on life functions  DNA packaged into chromosomes found in nucleus  Depending on the kingdom, can be unicellular, multicellular, heterotrophic, or autotrophic.

Bacteria  Includes simple bacteria and blue-green algae.  Some bacteria are chemosynthetic (make their own food with inorganic molecules); others heterotrophic  Bacteria classified classified by shape. by shape.

Examples of Bacteria Samonella E.coli E.coli Streptococcus

Blue-Green Algae  Although called algae, they are actually a type of bacteria known as cynobacteria.  They are found in rivers, lakes, damp soil, tree trunks, hot springs, and snow.  Similar to algae, they are autotrophic and have chlorophyll.  They exist as individual cells, in colonies, or in filaments.

Protists  Phyla include Algae, Protozoa, and Euglena  Algae are photosynthetic, have cell walls, and chloroplasts Kelp Spirogyra Spirogyra

Protists: Protozoa & Euglena  Protozoa are heterotrophic and are classified by method of locomotion.  Euglena contain chlorophyll and are photosynthetic Ameba: pseudopods Euglena: flagellum Paramecia: cilia

Fungi  Multicellular except for yeast (unicellular)  Heterotrophic  Extracellular digestion Athlete’s Foot Athlete’s Foot Bread Mold

Plants  Bryophytes: no vascular tissue (no true roots, leaves or stems -- mosses, liverworts  Tracheophytes: vascular tissue (xylem and phloem) --ferns, conifers, flowering plants --ferns, conifers, flowering plants Moss Ferns Ferns

Conifers & Flowering Plants

Animals

Evolutionary Relationships

Trends in Body Development  As you move from simple organisms such as sponges to more complex organisms, such as chordates we see changes in: Body organization (cells organized into tissues, organs and organ systems) Body organization (cells organized into tissues, organs and organ systems) Number of germ (embryonic) layers (tissues from which more specialized tissues develop) Number of germ (embryonic) layers (tissues from which more specialized tissues develop) Body symmetry Body symmetry A complete or incomplete digestive tract A complete or incomplete digestive tract Development (or not) of an internal cavity called a coelom Development (or not) of an internal cavity called a coelom

Germ Layers  Germ layers are the main layers that form during embryonic development.  Once the sperm and egg meet a fertilized egg, known as a zygote is formed.  The zygote immediately begins to divide through a process called cleavage eventually forming a solid ball of cells called the morula.

Germ Layers (cont’d)  The morula hollows out to form a single layer ball of cells called the blastula.  The blastula indents (pushes inward) to form the gastrula through the process of gastrulation.  In simpler (dibobastic) animals, there are only 2 layers formed – endoderm (inner layer) and the ectoderm (outer layer)  In more complex (triboblastic) organisms, 3 layers are formed – endoderm (inner layer), mesoderm (middle layer) and the ectoderm (outer layer)

Germ Layer Development

Body Symmetry  In general simple animals exhibit radial symmetry where body parts are arranged around a central axis.  Such a body arrangement allows the animal to interact with its environments from all directions. More complex animals exhibit bilateral symmetry where the body is organized along organized along a longitudinal a longitudinal axis and the left axis and the left and right sides and right sides are mirror are mirror images. images.

Terms Associated with Bilateral Symmetry  Dorsal: top or back of organism  Ventral: belly or underside of organism  Anterior: front portion of organism  Posterior: rear portion of organism

Cephalization  Along with bilateral symmetry comes cephalization or development of a head end (anterior) and a rear end (posterior).  Sensory cells, a brain or in simpler animals, ganglia (bunch of nerve cells) are clustered at the anterior end.  Digestive, excretory, and reproductive structures are located toward the posterior end.  This allows animals to move faster to either capture prey successfully or flee from predators.

Coelom  Coelom: a fluid-filled body cavity that is completely surrounded by a middle layer of tissue called mesoderm. The coelom is important in the development of advanced animals because it provides a space for complex organ systems to develop.  acoelomates: primitive animals such as flatworms do not have a coelom  pseudocoelomates: animals such as nematodes and roundworms have a fluid filled tube that is not completely lined by the mesoderm.  coelomates: most complex animals – includes annelids, mollusks, arthropods, and chordates.

Types of Coeloms

Animal Phyla  Porifera: filter feeders (sponges)  Coelenterates: hollow body cavity with one opening (hydra, jellyfish) Hydra

Animal Phyla  Annelids: worms with segmented bodies, openings at both ends, tube within tube body structure (earthworms, leeches, sandworms)  Arthropods: segmented body, jointed appendages, exoskeleton (grasshopper, lobster, spider)

Animal Phyla  Vertebrates: animals with true backbones (fish, frogs, snakes, and humans) (fish, frogs, snakes, and humans) Anaconda Anaconda Parrot Fish Tree Frog

Mammals  Warmblooded, have hair, produce milk  Monotremes: --have common duct (cloaca) for urination, defecation, and reproductive processes --lay eggs, mothers do retain eggs inside bodies for some time and provide eggs with nutrients --lay eggs, mothers do retain eggs inside bodies for some time and provide eggs with nutrients Duckbill Platypus

Marsupials  Offspring born in an immature state and must make their way into the mother’s pouch on the ventral side of body where development will be completed with nourishment from the mother’s milk.

Placental Mammals  Offspring develop inside female uterus, nourished by the placenta, an organ made of maternal and fetal tissue.  Offspring are born when they are fully developed  Infants have the most parental care of any living organisms.