Lecture 16

Deuterostome Animals

• Characteristics and classification in bio diversity.

• Focus: Echinoderms through Vertebrates.

Learning Outcomes

• 16.1: Distinguish deuterostomes from protostomes.

• 16.2: Compare synapomorphies in echinoderms and chordates.

• 16.3: Recognize key innovations in vertebrate evolution.

Animal Diversity

• Major Animal Phyla: ~30-35 phyla, with 1.5 million species identified.

• Protostomes include:

  • Lophotrochozoa (Phoronida, Gastrotricha, Annelida, Mollusca active groups).

  • Ecdysozoa (Arthropoda, Nematoda).

• Deuterostomes include:

  • Echinodermata (e.g., sea stars, sea urchins, sea cucumbers).

  • Chordata (vertebrates).

Echinoderms

• Characteristics:

  • Radial symmetry in adults with a loss of cephalization.

  • Key species: sea stars, sea urchins, and cucumbers.

• Endoskeleton: Made of calcium carbonate; affects marine biodiversity due to ocean acidification.

• Water Vascular System: Characteristic feature with tube feet, facilitating movement.

Chordata Characteristics

• Key Features:

  • Pharyngeal slits or pouches: Present in embryonic stages.

  • Dorsal Hollow Nerve Cord: Central nervous system component.

  • Notochord: Cartilaginous rod providing skeleton support.

  • Muscular, Post-Anal Tail: Extends beyond the digestive tract.

• Three Groups of Invertebrate Chordates:

  1. Cephalochordates: e.g., Lancelets (not fish).

  2. Urochordates: e.g., Tunicates (marine animals).

  3. Vertebrates: Include various evolutionary adaptations.

• Key Vertebrate Innovations:

  • Vertebrae: Protects spinal cord, cartilaginous or bony.

  • Cranium: Encloses the brain.

Evolutionary Innovations in Vertebrates

1. Vertebrae: Structural support, protecting the spinal chord.

2. Cranium: Protection for the brain, providing structural integrity.

3. Gills: Evolved from pharyngeal slits, essential for respiration in aquatic species.

4. Jaws: Enabled predation and diversification in feeding strategies.

5. Lungs and Lobed Fins: Adaptations to transition from water to land.

6. Limbs: Evolutionary adaptation facilitating terrestrial movement among tetrapods.

Indigenous Taxa

• Famous Echinoderms: Key role as predators (sea stars) and herbivores (urchins). Their removal leads to decreased biodiversity.

• Phylogeny in Fishes: Understanding evolutionary relationships among taxa (Monophyletic, Paraphyletic, Polyphyletic designations).

Evolutionary Adaptations in Fish

• Red-Lipped Batfish: Adaptation to walk with fins.

• Skates and Other Species: Exhibit adaptations for movement on land.