Lecture on Animal Biology

Introduction

• Initial perception of biology focused on animals.
• Realization that biology encompasses much more than just animals.

Personal Journey in Biology

• Initial lack of animal-focused courses in general bio.
• Specialization in cellular biology.
• Zoology course in graduate school was particularly impactful.

Fascination with Animals

• Universal long-standing human interest in animals.
• Understanding of cells, genetics, and ecology contributes to a deeper comprehension of animals.

Defining Animals

• Common Characteristics:
  • Multicellular, eukaryotic organisms.
  • Specialized cells and tissues in most animals.
  • Heterotrophic: consume food rather than producing it.
  • Generally ingest organic matter rather than absorbing it like fungi.
  • Mostly motile at some life stage.

Animal Characteristics Vocabulary

• Symmetry:
  • Radial Symmetry: Multiple planes of symmetry, useful for sessile animals.
  • Bilateral Symmetry: Divided into similar halves; facilitates forward movement.
• Cephalization: Concentration of nervous tissue in the head region.
• Triploblastic Animals:
  • Categorized into protostomes and deuterostomes based on embryonic development.
  • Protostomes: First opening (blastopore) develops into mouth.
  • Deuterostomes: First opening develops into anus.
• Germ Layers:
  • Triploblastic: Ectoderm, mesoderm, endoderm.
  • Diploblastic: Lack mesoderm.
• Coelom:
  • True body cavity derived from mesoderm, provides space for organ development.

Overview of Major Animal Phyla

Phylum Porifera

• Example: Sponges.
• Aquatic, mostly sessile, porous body.
• No true tissues or organs.
• Mostly asymmetrical, some radial symmetry, no cephalization, no coelom.

Phylum Cnidaria

• Examples: Jellies, sea anemones.
• Aquatic, one gut opening.
• Radial symmetry, no cephalization, no coelom.

Phylum Platyhelminthes

• Examples: Flatworms, planarians, tapeworms.
• Mostly parasitic, bilateral symmetry, cephalization, protostomes, no coelom.

Phylum Nematoda

• Examples: Hookworms, pinworms.
• Ecologically impactful, bilateral symmetry, cephalization, protostomes, pseudocoelom.

Phylum Mollusca

• Examples: Snails, clams, octopuses.
• Body structure: mantle, radula.
• Bilateral symmetry, cephalization, coelom, protostomes.

Phylum Annelida

• Examples: Earthworms, leeches.
• Segmented bodies, bilateral symmetry, cephalization, coelom, protostomes.

Phylum Arthropoda

• Examples: Insects, spiders, crustaceans.
• Jointed appendages, segmented exoskeleton.
• Bilateral symmetry, cephalization, coelom, protostomes.

Phylum Echinodermata

• Examples: Sea stars, sea urchins.
• Aquatic, regenerative abilities.
• Radial symmetry in adults, no cephalization, coelom, deuterostomes.

Phylum Chordata

• Examples: Vertebrates like fish, mammals.
• Defined by notochord, vertebral column develops from it in vertebrates.
• Bilateral symmetry, cephalization, coelom, deuterostomes.

Conclusion

• Emphasis on the diversity of animal phyla.
• Encouragement to continue exploring the animal kingdom.
• Reminder of the vast proportion of invertebrates among existing species.