Chapter 4

• Taxonomy is the systematic classification of organisms based on a set of characteristics used to assess similarities and differences
• Carolus Linnaeus


  Swedish botanist and anatomist who published "System of Nature" in 1748
• Linnaeus' classification was based on resemblances rather than evolutionary relationships, but it is still useful in reconstructing evolutionary history and study the patterns of relationships among organisms (phylogenetic systematics)
• Binomial Nomenclature


  Common names for organisms does not accurately reflect the type of organism
• Common names


  • Jelly Fish
  • Cray Fish
  • Silverfish
• Binomial Nomenclature


  Biologists use Latin scientific names to refer to organisms, with the first part being the genus and the second part referring to one species within the genus
• The first letter of the genus is capitalized, and the entire binomial is italicized, if not, then underlined
• Genus


  • Panthera
• Species


  • pardus
• Hierarchical Classification
• Bacteria was classified as belonging to plant kingdom by taxonomists due to the rigid cell walls of bacteria
• Fungi were classified as plants as well, because most fungi are unable to move around
• Any unicellular organisms that move and ingest food was considered a protozoans — were called animals
• In 1969, Robert H. Whittaker stated effectively that all living organisms can be placed in five major kingdoms

  Monera, Protista, Plantae, Fungi, and Animalia
• Characteristics of the five kingdoms


  • Prokaryotes
  • Eukaryotes
  • Cell type
  • Mode of Nutrition
  • Role in food chain
• The tree of life consists of three great domains: Bacteria, Archaea, and Eukarya
• Bacteria domain


  Includes most of the currently known prokaryotes, including the bacteria which are closely related to chloroplasts and mitochondria cells
• Archaea domain


  Consists of a diverse group of prokaryotic organisms that inhabits a wide variety of environments
• Eukarya domain


  Consists of all the organisms that have cells containing true nuclei, including many groups of single-cell organisms as well as multicellular plants, fungi, and animals
• Comparisons of complete genomes from the three domains show that, especially during the early history of life, there have been substantial interchanges of genes between organisms in the different domains by Horizontal Gene Transfer
• Monera Kingdom


  • Prokaryotic species
  • Microscopic organisms
  • Able to inhabit diverse environments
• Protists


  • Most diverse group of eukaryotes
  • Mostly unicellular, yet some are multicellular
  • Considered the "simplest eukaryotes"
  • Can be photoautotrophs, heterotrophs, or mixotrophs
• Protists habitats


  • Diverse, mostly aquatic and found wherever there is water
  • Found free-living or in symbionts with other organisms
• Fungi


  • Heterotrophs that feed by absorption using Exo-enzymes for digestion
  • Include species that live as decomposers (saprobes) and parasitic fungi that absorb nutrients from the cells of living hosts
• Fungal body structure


  Some exist as single cells known as yeasts, but most species are multicellular with a network of tiny filaments called hyphae that form an interwoven called a mycelium
• Animals


  • Eukaryotic
  • Multicellular and Heterotrophic
  • Have tissues that develop from embryonic layers
  • Use enzymes to digest their food only after they have ingested it
  • Lack cell wall and Reproduce Sexually
  • Bodies held together by Collagen
  • Have different Intercellular junctions
• Invertebrate Phyla


  • Porifera (Sponges)
  • Cnidaria (Corals)
  • Placozoa (Trichoplax)
  • Kinorhyncha (kinorhynch)
  • Platyhelminthes (Flatworm)
  • Rotifera (Rotifer)
  • Ectoprocta (Ectoproct)
  • Phoronida (Phoronid)
  • Brachiopoda (Brachipod)
  • Nemertea (Ribbon worm)
  • Acanthocephala (Acanthocephalan)
  • Ctenophora (Comb jellies)
  • Mollusca (Snail)
  • Annelida (Earth worm)
  • Loricifera (Loriciferan)
  • Priapula (Priapulan)
  • Nematoda (Roundworm)
  • Arthropoda (Scorpion)
  • Cycliophora (Cycliophoran)
  • Tardigrada (Tardigrade)
  • Onychophora (Onychophoran)
  • Hemichordata (Acorn worm)
  • Echinodermata (Sea star)
  • Chordata (Tunicates)
• Phylum Porifera (Sponges)


  • Live in fresh and marine waters
  • Suspension feeders
  • Range in size from few millimeters to few meters
  • Lack true tissue, but have several different cell types
  • Hermaphrodites
• Phylum Cnidaria (Corals)


  • Diversified into a wide range of sessile and floating forms
  • Include species such as jellyfish, corals and hydras
  • Have simple, diploblastic, radial body plan
  • Basic body plan is a sac with a central digestive compartment called the gastrovascular cavity
  • Carnivores that use tentacles arranged in a ring around their mouth to capture prey and push food into their gastrovascular cavity
• Phylum Platyhelminthes (Flatworms)


  • Mostly live in marine, fresh-water, and damp terrestrial habitats
  • Found in either a free-living form or parasitic form
  • Bodies are very thin, enabling gas exchange and elimination of nitrogenous waste by diffusion
  • Most have a gastrovascular cavity with only one opening
• Vertebrates


  • Animals with a backbone
  • Approximately 52,000 species
  • A subphylum of the phylum Chordata
• Vertebrate groups


  • Cephalaspidomorphi
  • Chondrichthyes
  • Amphibians
  • Reptiles
  • Mammals
• Early Vertebrates - Conodonts

  • Slender, soft-bodied vertebrates with prominent eyes and controlled by numerous muscles
  • Had paired fins and an inner ear with two semicircular canals that provided a sense of balance
  • Lacked jaws, but had a muscular pharynx which they used to suck in bottom-dwelling organisms or waste
• Fishes - Hag fishes


  • Least derived craniate (chordates that have a head) that still survive
  • Have a skull made up of cartilage, but lack jaws and vertebrae
  • Swim snake-like by using their segmental muscles to exert force against their notochord
  • Have a small brain, eyes, ears, and a nasal opening
  • Have tooth-like formations made of the protein keratin in their mouth
• Amphibians


  • Represented today by about 4,800 species of salamanders, frogs, and caecilians
  • Most are found in damp places
  • Rely heavily on their moist skin for gaseous exchange with the environment
  • Lay their eggs in water or moist environments on land, with eggs lacking a shell and dehydrating quickly in dry air
• Amphibian


  Means "two lives" or the metamorphosis of many frog species, where the larval tadpole stage is aquatic and herbivorous, and the adult stage is terrestrial and carnivorous
• Amphibian metamorphosis


  1. Tadpole develops legs, lungs, external eardrums, and a digestive system

  2. Gills disappear and the young frog crawls onto shore and becomes a terrestrial hunter
• Amphibian life cycle


  • Females lay eggs in the water which are then fertilized
  • Tadpole is an aquatic herbivore with a fishlike tail and internal gills
  • During metamorphosis, the gills and tail are resorbed, and walking legs develop
• Reptiles


  • Include lizards, snakes, turtles, crocodilians
  • Have scales containing keratin that create a waterproof barrier to prevent dehydration
  • Rely on their lungs alone for gas exchange
  • Most lay shelled eggs and are cold-blooded
• Birds


  • There are 8,600 species in the world
  • Lack a urinary bladder, and females of most species have only one ovary
  • Most obvious adaptations for flight are wings and feathers made of β-keratin
  • Power for flapping wings comes from contractions of breast muscles