Animal Kingdom Notes

The 3 Domain System

  • The three-domain system classifies all life into:

    • Bacteria
    • Archaea
    • Eukarya

  • Bacteria: Includes various types like Gram-positive and Gram-negative bacteria, cyanobacteria, and thermotoga.

  • Archaea: Contains extreme halophiles, methanogens, and hyperthermophiles.

  • Eukarya: Encompasses a wide range of organisms including:

    • Animals
    • Plants
    • Fungi
    • Protists (e.g., slime molds, amoeba, ciliates)
    • Euglenozoa
    • Chromista
    • Microspora

  • The diagram also suggests evolutionary relationships, with a universal ancestor at the base, leading to the three domains.

  • Organelles like mitochondria and chloroplasts are shown within the Eukarya domain, as well as cellular slime molds and plasmodial slime molds.

  • Terms like nucleoplasm and archaezoa are also present, indicating cellular components and early eukaryotes.

Kingdoms

Archaebacteria

  • Oldest known living organisms.
  • Thrive in extreme environments such as volcanoes, ocean floor, and mineral springs.
  • Single-celled and prokaryotic.

Eubacteria

  • Single-celled, prokaryotic bacteria.
  • Most bacteria in the world.
  • Very common and found everywhere.

Protista

  • Single-celled eukaryotic organisms.
  • Includes algae, slime molds, and free-living unicellular organisms.

Fungi

  • Multicellular eukaryotic organisms.
  • Eat by absorption.
  • Includes molds, mildews, mushrooms, and yeast.

Plantae

  • Multicellular, photosynthetic, eukaryotic organisms.
  • Includes all plants, mosses, and ferns.
  • Second largest kingdom.

Animalia

  • Largest of all kingdoms.
  • Multicellular eukaryotic heterotrophs that eat by ingestion.
  • Includes all animals from sponges to humans.

Animal Development

Factors Affecting the Animal Kingdom

  • Organisms are eukaryotic, multicellular, and heterotrophic
  • Cell Specialization and Division of Labor: Allows organisms to become larger and more complex with dedicated organ systems.

Organismal Development

  1. Sperm + egg → unicellular zygote
  2. Zygote division (mitosis): Division continues until a blastula (hollow ball of cells) forms.
  3. Gastrulation: One point on the ball folds inward, creating an internal cavity.

Body Symmetry and Directionality

  1. Asymmetrical: No form
  2. Radial: No left/right, has top/bottom
  3. Spherical: Ball shape
  4. Bilateral: Has top, bottom, left, right; can be split into matching sides
    1. Anterior: Head region
    2. Posterior: Away from head
    3. Dorsal: Back/top
    4. Ventral: Front/under

Phylum: Porifera (Sponges)

  • Simplest animals on the planet.
  • Radial symmetry.
  • Sessile (stuck in one place).
  • No mouth, nerves, or brain.
  • Eating: Filter-feeders – water is sucked through pores in the sides and out the top.
  • Reproduction: Asexually and sexually.
  • Respiration: Diffuse gases through the body wall.
  • Excretion: Out the top.
  • Poriferans filter the ocean, constantly taking in water and filtering out nutrients.

Phylum Cnidaria

  • Squishy animals that sting. Includes jellies, anemones, hydra, coral, and sea fans.
  • Two body forms: hydra and polyp.
  • Have a mouth and nerve net (can sense touch and will respond).
  • Eating: Tentacles with stinging cells around the mouth drag in food.
  • Respiration: Diffuse gases through body wall to breathe.
  • Excretion: Out the mouth.
  • Reproduction: Asexually and sexually.
  • Cnidarians have a nerve net and will react to touch.
  • Stinging cells called nematocysts in the tentacles paralyze prey; then, the tentacles drag the prey into the mouth for digestion.

Phylum Platyhelminthes (Flatworms)

  • Acoelomate: Have a middle layer called mesoderm but no body cavity.
  • Have muscles for movement.
  • Bilateral symmetry.
  • Cephalization: Nerves and sense receptors concentrated in one area, similar to a head with a brain.

Class Turbellaria

  • Free-living flatworms; Planarians.
  • Eyespots to sense light/dark.
  • Ganglia: Primitive brain beneath eyespots.
  • Mouth on the ventral side of the body.
  • Extendable tube called pharynx for eating.
  • Can regenerate when cut in half.

Class Cestoda

  • Parasites; tapeworms.
  • Head called scolex with hooks and suckers to attach to host.
  • Body segments called proglotids.
  • Protective covering called cuticle.

Class Trematoda

  • Parasites; flukes.
  • Have tegument to protect body.
  • Common in sushi/sashimi.
  • Can have complex life cycles/infection cycles.

Phylum Rotifera

  • Pseudocoelomate: Have a false body cavity (gap, but nothing in it).
  • Complete digestive tract (mouth and anus!).
  • Have mastax (primitive jaw).
  • Ring of cilia around the mouth to draw food in.
  • Microscopic.

Phylum Nematoda

  • Roundworms.
  • Pseudocoelomate.
  • Complete digestive tract.
  • Mostly parasites.
  • Two sexes!
  • Transmitted through unclean water, undercooked meat, eggs excreted and found in soil.