Classification of Living Things

Classification of Living Things

Objectives

• Define classification as proposed by Carl Linnaeus.
• Differentiate between prokaryote and eukaryote.
• Draw and label a bacterial cell.
• Explain the hierarchy of taxonomy groups.
• Examine species within the five kingdoms.
• State the characteristics of each plant phylum.
• State the characteristics of each animal phylum.

Introduction

• Millions of organisms live on Earth.
• Carl Linnaeus developed a system for classifying living organisms.

Classification (Taxonomy)

• Classification groups organisms based on physical and biological similarities.
• Classification is also known as taxonomy.

Taxonomy

• Taxonomy is the science of naming and classifying organisms.
• Binomial nomenclature is a two-term system for naming organisms.
• Carl Linnaeus developed binomial nomenclature.

Classification Mnemonic

• Mnemonic: "Dear King Phillip Came Over For Green Salad"
• Represents: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Each species has two Latin names: Genus + species.
• Example: Homo sapiens (Genus Homo, species sapiens).

Domains of Life

• Bacteria:
  • Chromosomes are not enclosed within a nucleus (prokaryotic).
  • Unicellular.
  • Example: Bacteria.
• Eukarya:
  • Chromosomes are enclosed within a nucleus (eukaryotic).
  • Possess a true nucleus.
  • Multicellular.
  • Examples: Plants, animals, and fungi.
• Archaea:
  • Chromosomes are not enclosed within a nucleus (prokaryotic).
  • Unicellular.
  • Live in harsh environments.

Prokaryote: Bacterial Cell

• Characteristics:
  • No true nucleus.
  • No organelles with membranes (mitochondria, chloroplasts, ER).
  • Cell wall present.
  • Simple organism.

Viruses

• Viruses are neither prokaryotes nor eukaryotes.
• Composed of a small piece of DNA or RNA surrounded by a protein coat.
• Parasitic: require a host to survive; live inside another cell.

Life Domains and Kingdoms

• Domains:
  • Archaea
  • Bacteria
  • Eukaryotes
• Kingdoms:
  • Monera (Prokaryotae)
  • Protoctista
  • Fungi
  • Plantae
  • Animalia

Kingdom Monera (Prokaryotae)

• Characteristics:
  • Unicellular.
  • No nucleus, mitochondria, chloroplasts, or endoplasmic reticulum.
  • Cell wall present.
• Examples:
  • Escherichia coli
  • Nitrogen-fixing bacteria
  • Nitrifying bacteria

Kingdom Protoctista (Protoctists or Protists)

• Simple organisms mainly living in water.
• Examples:
  • Algae
  • Protozoa (amoeba, paramecium)
• Algae:
  • Plant-like; can be multicellular or unicellular.
  • Make food by photosynthesis.
• Protozoa:
  • Animal-like.
  • Do not photosynthesize; heterotrophs.

Kingdom Fungi

• Characteristics:
  • Unicellular or multicellular.
  • Cell walls present.
  • No chlorophyll.
  • Feed saprophytically or parasitically.
• Examples:
  • Mushrooms
  • Molds (e.g., Mucor/bread mold, mildew)
  • Yeasts

Kingdom Plantae

• Characteristics:
  • Unicellular or multicellular.
  • Cell walls present.
  • Chlorophyll present.
  • Feed by photosynthesis.
• Examples:
  • Pines
  • Mosses
  • Ferns
  • Flowering plants

Kingdom Animalia

• Characteristics:
  • No cell walls.
  • No chlorophyll.
  • Feed heterotrophically.
• Examples:
  • Sponges
  • Corals
  • Crabs
  • Insects
  • Fish

Phyla of Kingdom Plantae

• Bryophytes
• Ferns
• Conifers
• Flowering Plants

Phylum Angiospermophyta

• Flowering plants (angiosperms).
• Characteristics:
  • Roots, stems, and leaves.
  • Xylem and phloem.
  • Reproduce by seeds.
  • Seeds produced inside ovary, inside flower.
• Examples:
  • Corn (Zea mays)
  • Wax apple (Syzygium samarangense)

Phylum Coniferophyta

• Conifers.
• Seed plants without real flowers; seeds grow inside cones.
• Characteristics:
  • Roots, stems, and leaves.
  • Xylem and phloem.
  • Reproduce by seeds inside cones.
• Examples:
  • Pine trees

Phylum Bryophyta

• Mosses and liverworts (bryophytes).
• Live on land but need wet places for fertilization.
• Characteristics:
  • Simple stems and leaves.
  • Single-celled rhizoids (rootlets).
  • No xylem or phloem.
  • Reproduce by spores.
• Examples:
  • Liverwort (Pellia epiphylla)
  • Moss (Grimmia pulvinata)

Phylum Filicinophyta

• Ferns; need water for fertilization but can live in slightly drier places than bryophytes due to xylem and phloem.
• Characteristics:
  • Roots, stems, and leaves.
  • Xylem and phloem.
  • Reproduce by spores that develop on the underside of leaves.
• Examples:
  • Tree fern (Cythea arborea)

Phyla of Kingdom Animalia

• Porifera
• Cnidaria
• Echinodermata
• Mollusca
• Platyhelminthes
• Nematoda
• Annelida
• Arthropoda
• Chordata

Phylum Porifera

• Sponges.
• Characteristics:
  • Bodies contain a single cavity.
  • Lack tissues and organs.
  • Stationary organisms.
• Examples:
  • Giant barrel sponge (Xestospongia muta)
  • Yellow tube sponge (Aplysina fistularis)

Phylum Cnidaria

• Jellyfish, sea anemones, and corals.
• Characteristics:
  • Bag or umbrella-shaped body.
  • Gut has one opening (mouth).
  • Mouth surrounded by tentacles.
• Examples:
  • Portuguese man-of-war (Physalia physalis)
  • Immortal Jellyfish (Turritopsis dohrnii)

Phylum Echinodermata

• Organisms with spines or bumps on their surfaces.
• Characteristics:
  • Bodies have radial symmetry.
  • Body walls made of calcium carbonate.
  • Tube feet with suction pads.
• Examples:
  • Basket star (Gorgonocephalus eucnemis)
  • Purple sea urchin (Strongylocentrotus purpuratus)

Phylum Mollusca

• Second-largest group of invertebrates; largest group of named marine organisms; includes snails, slugs, and octopuses.
• Characteristics:
  • Soft, moist, unsegmented bodies.
  • Muscular foot.
  • Many have shells.
• Examples:
  • Giant African land snail (Achatina fulica)
  • Blue-ringed octopus (Hapalochlaena lunulata)

Phylum Platyhelminthes

• Flatworms.
• Characteristics:
  • Long, flat, unsegmented body.
• Examples:
  • Tiger flatworm (Maritigrella crozieri)
  • Tapeworm, liver fluke

Phylum Nematoda

• Roundworms.
• Characteristics:
  • Elongated, round, unsegmented body.
  • Body has pointed ends.
• Examples:
  • C. elegans (Caenorhabditis elegans)
  • Hookworm, pinworm, heartworm

Phylum Annelida

• Segmented worms.
• Characteristics:
  • Elongated body divided into segments.
• Examples:
  • Ragworms (Nereididae)
  • Earthworms, leech

Phylum Arthropoda

• Largest group of invertebrates.
• Characteristics:
  • Exoskeleton.
  • Segmented body.
  • Many pairs of jointed legs.
• Classes of Arthropods:
  • Insects (roach, ant, bee)
  • Crustaceans (crabs, lobster, shrimp)
  • Arachnids (spider, tick, scorpion)
  • Myriapods (millipede, centipede)

Phylum Chordata

• Vertebrates.
• Characteristics:
  • Endoskeleton.
  • Backbone.
• Classes of Chordates:
  • Aves (birds)
  • Pisces (fish)
  • Amphibians
  • Reptiles
  • Mammals