The Kingdom Animalia

The Kingdom Animalia

  • Classification of Life

    • Six Kingdoms:

      • Animalia (Multicellular, eukaryotic)

      • Plantae (Multicellular, eukaryotic)

      • Fungi (Multicellular, eukaryotic)

      • Protista (Eukaryotic, unicellular and multicellular)

      • Eubacteria (Unicellular, prokaryotic)

      • Archaebacteria (Unicellular, prokaryotic)

Overview of the Animal Kingdom

  • Characteristics:

    • Eukaryotic and Multicellular

    • Heterotrophic (99% ingestive feeding)

    • Mainly reproduce sexually, producing an embryo

    • Motile (capable of movement)

    • Lack cell walls; many possess a skeleton for structure

Animalia Phylogeny

  • Emergence of Animals:

    • First appeared around 540 million years ago.

    • Most fossil evidence belongs to a period known as the Cambrian explosion (505 million years ago).

The Origin of Animals

  • Common Ancestor:

    • Likely a colony of flagellated protists.

    • Formation of a cavity due to indentation in spherical arrangement of cells.

    • Allowed easier capture and digestion of food.

    • Specialization of some cells for feeding purposes.

Animal Embryos

  • Development Process:

    • Zygote divides to form a hollow blastula (cup-shaped cluster of cells).

    • The arrangement has double lining, with one layer specializing in digestion, akin to sponges.

    • Blastula undergoes inward pinching to form the gastrula (produces three germ layers).

Classification Characteristics of Animals

  • Used in Classification:

    1. Number of body layers

    2. Presence of body cavity

    3. Body plan symmetry

    4. Backbone presence

    5. Level of organization

    6. Segmentation

    7. Type of movement

    8. Reproductive strategies

    9. Degree of cephalization (presence of a head)

Germ Layers in Animals

  • Number of Germ Layers:

    • Distinguish animal phyla by germ layers:

      • Ectoderm: Outer layer (develops into skin, nerves, etc.)

      • Endoderm: Inner layer (develops into stomach, lungs, liver, pancreas, etc.)

      • Mesoderm: Middle layer (develops into blood, muscles, kidneys, reproductive organs, etc.)

Body Cavity

  • Coelom:

    • A body cavity that contains internal organs.

    • Distinguishes animal phyla by presence or absence of a coelom.

Animal Symmetry

  • Types of Symmetry:

    • Most animals exhibit:

      • Radial Symmetry: Symmetry around a central axis (e.g., jellyfish, starfish).

      • Bilateral Symmetry: Symmetry around a midline (e.g., humans).

    • Asymmetry: No symmetry (e.g., sponges).

Bilateral Symmetry Groups

  • Gastrulation Types:

    • Protostomes: Mouth forms before anus (e.g., snails).

    • Deuterostomes: Anus forms before mouth (e.g., whales).

Vertebrates vs. Invertebrates

  • Cell Specialization:

    • Presence of specialized nerve cells coordinating movements.

  • Vertebrates:

    • Animals with a backbone (or notochord, a flexible rod).

  • Invertebrates:

    • Animals lacking a backbone.

Phyla of Kingdom Animalia

  • Diverse Examples:

    • Vertebrates:

      • Mammalia, Aves, Reptilia, Osteichthyes, Chondrichthyes, Agnatha (lamprey).

    • Invertebrates:

      • Examples include Porifera (sponges), Cnidaria (hydras, jellyfish), and Arthropoda (insects, spiders).

Major Categories of Animal Phyla

  • Three Main Categories:

    1. Simple Invertebrates: Porifera, Cnidaria.

    2. Protostome Invertebrates: Platyhelminthes, Rotifera, Mollusca, Annelida, Nematoda, Arthropoda.

    3. Deuterostomes: Echinodermata, Chordata.

Invertebrate Examples: Porifera and Cnidaria

  • Porifera (Sponges):

    • Aquatic, asymmetrical, no tissues or organ systems, specialized cells with flagella to capture food.

  • Cnidaria:

    • Aquatic, radially symmetrical, possess specialized nerves, muscles, and stinging tentacles, with a gastrovascular cavity.

Worm Phyla Structures

  • Platyhelminthes:

    • Unsegmented flatworms, first true tissues, incomplete digestion, and no coelom.

  • Nematoda:

    • Roundworms with complete digestion and a pseudo-coelom.

  • Annelida:

    • Segmented worms with a primitive organ system, ganglia brain, and a true coelom.

Specialized Invertebrates: Rotifera and Tardigrada

  • Rotifera:

    • Microscopic aquatic animals that utilize cilia for food intake.

  • Tardigrada:

    • Eight-legged organisms known for extreme resilience and survival in harsh conditions.

Phylum Mollusca

  • Characteristics:

    • Have a coelom, organized organ systems, unsegmented bodies divided into three parts: foot, visceral mass, mantle (can secrete a shell).

Phylum Arthropoda

  • Characteristics:

    • Segmented bodies and coelom, exoskeleton is made of chitin, complex sensory systems, and an open circulatory system.

    • Examples include insects, spiders, and crustaceans.

Phylum Echinodermata

  • Properties:

    • Radially symmetrical with an endoskeleton and coelom.

    • Notable members include starfish, sea cucumbers, and sea urchins.

Phylum Chordata

  • Characteristics:

    • Vertebrates characterized by an endoskeleton and coelom.

    • Diverse classes include jawless fish, cartilaginous fish, bony fish, amphibians, reptiles, birds, and mammals.

Chordate Phylogeny

  • Progression:

    • From ancestral chordates to various groups through the evolution of features (vertebrae, jaws, and limbs).