Study Notes on Animal Life and Characteristics

Introduction to Animals

  • Focus on Chapter 33: Rainbow Snake, Farancia erytrogramma

Fascinating Animals

  • Question posed: "What animal do you find most fascinating?"

  • Requirement: The Slido app must be installed on every computer used for presentations.

Outline of Topics

  • Animalia Phylogenetic Tree

  • Definition of Animals

  • Limits of Size and Shape of Animals

  • Basics of Animal Bioenergetics

  • Contains organisms with a nucleus and organelles.

  • Major groups include:

    • Unikonts

    • Chromalveolates

    • Archaeplastida (Plantae)

    • Opisthokonts

    • Excavates

    • Rhizaria

    • Discicristates

    • Green Plants: includes green algae, prasinophytes, and land plants.

    • Rhodophyta: red algae.

    • Glaucophytes: microalgae with chloroplasts like cyanobacteria (e.g., Cyanophora).

Animal Classification

  • Animals classified as Metazoa.

  • Other groups:

    • Choanoflagellates: collared-flagellates, precursors to animals.

    • Filasterea

    • Ichthyosporea

    • Fungi: includes mushrooms, yeasts, and molds.

    • Nucleariidae: group of filose amoebae (e.g., Nuclearia).

    • Amoebozoa: includes amoebae, slime molds, and parasitic protists.

    • Cercozoa: amoeboflagellates (e.g., euglyphids).

    • Foraminifera: complex cells with reticulopodia and a shell.

    • Radiolaria: includes Polycystina and Acantharia.

    • Alveolates: includes dinoflagellates, ciliates, apicomplexan parasites.

    • Stramenopiles: e.g., water molds, diatoms, brown algae, and chrysophytes.

    • Hacrobia: groups like Haptophyta, Cryptomonads, etc.

    • Malawimonads

    • Euglenozoa: including euglenids and kinetoplastids (e.g., Euglena, Trypanosoma).

    • Heterolobosea: amoeboflagellates with discoidal mitochondrial cristae.

    • Jakobida: free-living, heterotrophic flagellates.

    • Parabasalids: includes trichomonads and hypermastigotes (e.g., Trichomonas, Trichonympha).

    • Fornicata: group of diplomonads and retortamonads (e.g., Giardia).

    • Preaxostyla: includes oxymonads and Trimastix.

    • Uncertain Protists: mention of organisms not yet classified.

Tree of Life: Eukaryotes
Evolution of the Animal Kingdom

  • Oldest Fossils: dating back 700 million years.

  • Origin: Animals likely evolved from a colonial choanoflagellate protist ancestor.

  • Cambrian Explosion: occurred around 530 million years ago, marking rapid diversification of animal forms.

Precambrian Milestones

  • Time period: 4.6 billion years ago to 541 million years ago.

  • Oldest Animal Fossils: dated at 650 million years ago.

  • Significance: This era represents the story of life in the seas.

  • Fungi Presence: Fungi existed during the late Proterozoic; identified as aquatic, flagellated cells.

  • Green Algae: Ancestors of plants were present, but true plant evolution did not begin until 500 million years ago.

Characteristics Defining an Animal

  • Discussion on the various forms of animal cells, organelles, and structures needed to define an animal.

    • Chromatin

    • Animal Cell Components:

      • Nucleolus

      • Glycosomes

      • Smooth Endoplasmic Reticulum

      • Cytosol

      • Lysosomes

      • Mitochondria

      • Centrioles

      • Centrosome

      • Peroxisomes

      • Nuclear envelope and nucleus

      • Plasma membrane

      • Rough Endoplasmic Reticulum

      • Ribosomes

      • Golgi apparatus

      • Exocytosis processes.

Body Plans of Animals

  • Discussed are three primary body plans:

    • Asymmetrical

    • Radial Symmetry

    • Bilateral Symmetry

Directional Terms:
- Anterior (front)  
- Dorsal (top)  
- Ventral (bottom)  
- Posterior (back)
Aquatic Animals

  • Asymmetrical: Example includes sponges with no recognizable pattern.

  • Radial Symmetry: Could be divided into equal sections along a central axis; examples include starfish, jellyfish, sea anemones.

  • Bilateral Symmetry: Aquatic and land animals displaying high levels of mobility; mirror image arrangement leads to body complexity, with cephalization becoming prominent in advanced species.

Limitations on Size and Shape of Animals

  • Aquatic vs. terrestrial constraints discussed:

    • Aquatic Animals: Fusiform shapes to minimize drag and enhance swimming speed.

    • Land Animals: Constrained by gravity affecting their body mass and required speeds.

Maximum Speed of Assorted Animals

  • Speed Data:

    • Cheetah: 113 km/h (70 mph)

    • Quarter Horse: 77 km/h (48 mph)

    • Fox: 68 km/h (42 mph)

    • Shortfin Mako Shark: 50 km/h (31 mph)

    • Domestic House Cat: 48 km/h (30 mph)

    • Human: 45 km/h (28 mph)

    • Dolphin: 32-40 km/h (20-25 mph)

    • Mouse: 13 km/h (8 mph)

    • Snail: 0.05 km/h (0.03 mph)

Body Size and Animal Physiology

  • Discussion on how form relates to function in anatomy and physiology, using examples of finches based on their food source:

    • Geospiza fuliginosa: Small seeds

    • Geospiza fortis: Medium seeds

    • Geospiza magnirostris: Large seeds

    • Certhidea olivacea: Insects and nectar.

Factors Limiting Animal Size

  • Influencing factors include:

    • Food Availability and environment (carrying capacity)

    • Need for Efficient Movement: Increasing muscle mass as size increases.

    • Support System: Body size must align with skeletal capacity.

Exoskeleton Characteristics

  • Hard Shell Composition: Made of chitin and calcium carbonate, providing protection, minimizing water loss, and muscle attachment sites.

  • Growth Dynamics: New exoskeleton must be produced before the old one is shed, leading to vulnerabilities during growth phases and increased thickness needed.

    • Most animals with an exoskeleton (e.g., insects, spiders, crustaceans) tend to be small.

Endoskeleton Characteristics

  • Composition: Internal skeleton made of bones and cartilage.

  • Body size determined by the skeletal system's support of muscle and tissue movement.

  • Bone growth occurs in small increments throughout life.

Effect of Size on Physiology

  • Square-Cube Law: As animals grow larger, volume increases more rapidly than surface area, resulting in greater strain on the skeletal system.

Summary of the Square-Cube Law

  • Surface area scales with the square of length while volume scales with the cube of length, leading to increased difficulty in supporting larger weights due to greater volume.

Impact of Surface Area to Volume Ratio on Diffusion

  • Diffusion Defined: The net movement of substances from areas of high concentration to low concentration.

  • Importance of diffusion in cellular processes:

    • Oxygen and nutrients entering cells.

    • Waste products exiting cells (e.g., urea).

  • A larger surface area to volume ratio enhances the rate of molecular diffusion, supporting effective cellular function.

Comparative Surface Area to Volume Ratio Analysis

  • Example scenarios evaluating the size of animals (10 cm vs. 2 cm) reference impacts on diffusion rates based on surface area to volume ratios.

Conclusion on Molecular Diffusion

  • Essential in animal biology for facilitating processes including gas exchange, nutrient transport, and waste removal, ensuring cellular and organismal efficiency.