Classification of Organisms

1. Classification of Organisms

2. Classification of Organisms • The study of the kinds and diversity of organisms and their evolutionary relationships is called systematics or taxonomy • Taxonomy is the work involved in the original description of a species. • Systematics is the assigning of species into evolutionary groups.

3. Father of Modern Classification • The modern classification system originated with the work of Carolus Linnaeus • he recognized the different species could be grouped into broader categories based on shared characteristics • any grouping of animals that shares a particular set of characteristics forms an assemblage called a taxon

4. Modern taxonomists use 7 taxa: • kingdom, phylum, class, order, family, genus and species • as taxa increase organisms get more specific

5. Binomial Nomenclature: • when a species is talked about only the genus and species names are used • this is called thescientific name • unique to each type of organism • Required by the International Code of Zoological Nomenclature

6. Writing Scientific Names • the genus names is always capitalized • both names are either italicized or underlined • leave a space in the underline between names ex. Homo sapien Felis leo Quercusrubra

7. Kingdoms of Life • In 1969, Robert H. Whitaker classified kingdoms based on cellular organization and mode of nutrition • this lead to the formation of the 5 kingdoms

8. 5 Kingdoms of Classification: Monera: comprised of bacteria and cyanobacteria • distinguished by being single cell prokaryotes Protista: comprised of Amoeba, Paramecium etc…. • distinguished by being single celled eukaryotes Plantae: multi-cellular photosynthetic eukaryotes • plants have cell walls and are non-motile

9. 5 Kingdoms of Classification: Fungi: multi-cellular heterotrophic eukaryotes • fungi have cell walls and usually non-motile • digest organic matter extra-cellularly (outside of cell) and absorb the breakdown products Animalia: multi-cellular heterotrophic eukaryotes • animal cells lack a cell wall and usually motile • feed by ingesting other organisms or parts of other organisms

10. Monera prokaryote single-cell Protista eukaryote multi-cell Plantae eukaryote multi-cell autotrophic Fungi eukaryote multi-cell heterotrophic, external digestion Animalia eukaryote multi-cell heterotrophic, internal digestion

11. DOMAINS??? • Many taxonomists have pushed the idea that the five kingdom system isn’t enough • they feel that organisms share too much similarities and need to be grouped otherwise • the push has led to the addition of 3 domains

12. 3 Domains • Archae: bacteria that live in extreme conditions • Eubacteria: “true bacteria” • Eukarya: all eukaryotic organisms

13. Patterns of Organization • Once the kingdom of an organism has been decided other aspects of the organism must be looked at to determine it’s classification • Symmetry: describes how the parts of an animal are arranged around a point or an axis

14. Types of symmetry • Asymmetry: the absence of a central point or axis around which body parts are equally distributed • characterizes most protists and many sponges • not known to be an adaption or advantage to anything • organisms do not develop complex communication, sensory, or locomotor functions

15. Types of symmetry • Radial Symmetry: arrangement of body parts such that any plane passing through the central oral-aboral axis divides the animal into mirror images • oral-aboral axis: one point of reference is the mouth (oral end) and a second point of reference is the end opposite the mouth (aboral end) • often modified by the arrangement of some structures in pairs , or in other combinations, around the central oral-aboral axis

16. Types of symmetry • Bilateral Symmetry: the arrangement of body parts such that a single plane, passing between upper and lower surfaces and through the longitudinal axis of an animal, divides the animal into right and left mirror images. • characteristic of active, crawling, or swimming animals • tend to move in one direction, so one end is generally more complex Cephalization: the development or formation of a distinct head

17. Planes of symmetry are used to describe the organisms based on the relationships of body parts • Not all animals are easily described and can be confusing if different people try to explain them differently • To make it simpler some terms have been universally adopted.

18. Terms of Directions: • Aboral: the end opposite the mouth • Oral: the end containing the mouth • Anterior: the head end; usually the end of a bilateral animal that meets its environment • Posterior: the tail end • Caudal: toward the tail • Cephalic:toward the head • Distal: away from the point of attachment of a structure on the body (the toes are distal to the knee)

19. Terms of Directions: • Proximal: toward the point of attachment of a structure on the body (the hip is proximal to the knee) • Dorsal: the back of an animal; usually the upper surface; synonymous with posterior for animals that walk upright • Ventral:the belly of an animal; usually the lower surface; synonymous with anterior for animals that walk upright • Inferior: below a point of reference (the mouth is inferior to the nose in humans) • Superior: above the point of reference (the neck is superior to the chest) • Lateral: away from the plane that divides a bilateral animal into mirror images • Medial (median): on or near the plane that divides a bilateral animal into mirror images

20. Other Patterns of Organization • Unicellular (Cytoplasmic) level: all single celled organisms • characteristic body plan of the Protista • is not “simple” • must provide for locomotion, food acquisition, digestion, water and ion regulation, sensory perception, and reproduction all in a single cell • colonies can exist, but show little signs of interdependence, cooperation, or coordination of function

21. Other Patterns of Organization • Diploblastic Organization: simplest tissue-level organization • tissue is derived from two embryonic layers • Ectoderm: gives rise to the epidermis, the outer layer of the body wall • composed of epithelial and muscular cells • Endoderm: gives rise to the gastrodermis, the tissue that lines the gut cavity • composed of digestive and muscular cells • between the epidermis and gastrodermis is the mesoglea, a noncellular layer • cells in each layer are functionally interdependent

22. Other Patterns of Organization • Triploblastic Organization: tissues are derived from three embryological layers • like diploblastic, the ectoderm forms the outer layer and the endoderm lines the gut • in between these two layers is the mesoderm: which gives rise to supportive, contractile, and blood cells • most organisms have organ-system level of organization

24. Triploblastic Subgroups • Based on the presence of and what kind of body cavity they have. Body Cavity: a fluid-filled space in which the internal organs can be suspended and separated from the body wall

25. Why are Body Cavities advantageous? • Provide more room for organ development. • Provide more surface area for diffusion of gases, nutrients, and wastes into and out of organs • Provide and area for storage. • Often act as hydrostatic skeletons. • Provide a vehicle for eliminating wastes and reproductive products from the body • Facilitate increased body size.

26. Triploblastic Subgroups: • Triploblastic Acoelemate Pattern: the mesoderm layer is a relatively solid mass of cells between ectodermal and endodermal layers • acoelemate means “without” a “cavity” • some of the mesodermal cells are parenchyma: loosely organized cells not specialized for a specific function

27. Triploblastic Subgroups: • Triploblastic Pseudocoelemate Pattern: • pseudocoelom: a body cavity not entirely lined by mesoderm • No muscular or connective tissues are associated with the gut tract • No mesodermal sheet covers the inner surface of the body wall • No membranes suspend organs in the body cavity

28. Triploblastic Subgroups: • Triploblastic Coelemate Pattern: • coelem: a body cavity completely surrounded by mesoderm • peritoneum: thin mesodermal sheet that lines the inner body wall . • serosa: thin mesodermal sheet that lines the outside of visceral organs. • peritoneum and serosa are continuous and suspend visceral organs in the body cavity. • mesentery: the suspending sheets of organisms.

30. Three major groups of the Animal Kingdom: • Mesozoa: includes phylum Mesozoa, or the mesozoans • Parazoa: includes phylum Porifera, or the sponges • Eumetazoa: includes all other phyla • Eumetazoa are further divided into two groups based on body symmetry • Radiata: animals that have radial symmetry • Bilateria: animals that have bilateral symmetry

31. Bilateria animals are divided into two group based on embryological characteristics Comparative Embryology: studies based on the observation that embryological events may be similar because of shared ancestry

32. Two Bilateria Groups: • Protostomes: include animals in the phyla Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, and others • Deuterstomes: include animals in the phyla Echinodermatat, Hemichrodata, Chordata, and others.