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Week 7: Deuterostomes

Week 7: Deuterostomes. Review: Protostomes vs. Deuterostomes. Similarities : Bilaterally symmetric Triploblastic Coelomates Differences: Initial pore development (anus first in deuterostomes) Process of coelom formation in embryonic stages. Scientific Method: Important Questions.

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Week 7: Deuterostomes

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  1. Week 7: Deuterostomes

  2. Review: Protostomes vs. Deuterostomes • Similarities: • Bilaterally symmetric • Triploblastic • Coelomates • Differences: • Initial pore development (anus first in deuterostomes) • Process of coelom formation in embryonic stages

  3. Scientific Method: Important Questions • What are the big patterns? • What processes led to that pattern? • Physiological mechanisms • Developmental processes • Understanding evolutionary history • Adaptive significance • Why should we care?

  4. Echinoderms (“spiny skin”) Sea stars, sea urchins, sea cucumbers

  5. Echinoderms Bilaterians (larvae are bilaterally symmetric, but adults have five-sided radial symmetry) Endoskeletons = hard structures made from CaCO3 inside epidermal tissue, protection and support

  6. Echinoderms • Water vascular system= branching, fluid-filled tubes • Controls the tube feet (movement and feeding)

  7. Hemichordata “Acorn worms”

  8. Xenoturbellida

  9. Chordata Sea squirt

  10. Chordate Synapomorphies Pharyngeal gill slits Dorsal hollow nerve cord Notochord Muscular, post-anal tail

  11. Chordate Synapomorphies Pharyngeal gill slits Dorsal hollow nerve cord Notochord Muscular, post-anal tail

  12. Cephalochordates (lancelets) • “Fish-like,” burrow in sand, suspension feed • Muscle contractions on either side of notochord help with movement

  13. Urochordates (sea squirts) • Pharyngeal gill slits help with feeding and gas exchange • Nerve cord, notochord, and tail help with swimming

  14. Vertebrates • Brain and spinal cord (the dorsal hollow nerve cord)– nerve cells that run from brain to posterior of body • Pharyngeal pouches in embryos • Notochord only in embryos, replaced with vertebrae (important segmentation)

  15. Chordates: Vertebrates • Pharyngeal gill slits • Dorsal hollow nerve cord • Notochord • Muscular, post-anal tail Vertebrates: • Pharyngeal pouches, not slits • Spinal cord, not dorsal hollow nerve cord • *Vertebrae, not notochord

  16. Vertebrates: Major Synapomorphies • Vertebrae (column of cartilaginous or bony structures; protects spinal cord) • Cranium (bony, cartilaginous, or fibrous case enclosing the brain; protects brain and eyes)

  17. Key innovations 480 mya: Bony exoskeleton 440 mya: Jaws 420 mya: Bony endoskeleton 365 mya: Limbs for moving on land (tetrapods) 340 mya: Amniotic egg

  18. Question 1 • What synapomorphy distinguishes animals as a monophyletic group, distinct from choanoflagellates? • Multicellularity • Movement via hydrostatic skeleton • Growth by molting • Ingestive feeding

  19. Question 1 • What synapomorphy distinguishes animals as a monophyletic group, distinct from choanoflagellates? • Multicellularity • Movement via hydrostatic skeleton • Growth by molting • Ingestive feeding

  20. Question 2 • Which of the following patterns in animal evolution is correct? • All tripoblasts have a coelom • All tripoblasts evolved from a common ancestor that had a coelom • Sponges have epithelial tissues that line an enclosed fluid-filled cavity • Bilateral symmetry and cephalization evolved once

  21. Question 2 • Which of the following patterns in animal evolution is correct? • All tripoblasts have a coelom • All tripoblasts evolved from a common ancestor that had a coelom • Sponges have epithelial tissues that line an enclosed fluid-filled cavity • Bilateral symmetry and cephalization evolved once

  22. Question 3 Which of the following patterns in animal evolution is correct? Segmentation evolved once Coelom was lost or reduced in many lineages Sponges lack true tissue and are asymmetrical Radial symmetry evolved once

  23. Question 3 Which of the following patterns in animal evolution is correct? Segmentation evolved once Coelom was lost or reduced in many lineages Sponges lack true tissue and are asymmetrical Radial symmetry evolved once

  24. Question 4 In a “tube within a tube” what is the interior tube? Ectoderm Mesoderm The coelom The gut

  25. Question 4 In a “tube within a tube” what is the interior tube? Ectoderm Mesoderm The coelom The gut

  26. Question 5 What is the diagnostic trait(s) of vertebrates? Vertebrae and cranium Jaws and spinal cord Endoskeleton constructed of bone Endoskeleton of reinforced cartilage

  27. Question 5 What is the diagnostic trait(s) of vertebrates? Vertebrae and cranium Jaws and spinal cord Endoskeleton constructed of bone Endoskeleton of reinforced cartilage

  28. Question 6 Which lineages make up the living amniota? Reptiles and mammals Viviparous fishes Frogs, toads, salamanders, and caecilians Hagfish, lampreys, and cartilaginous fishes

  29. Question 6 Which lineages make up the living amniota? Reptiles and mammals Viviparous fishes Frogs, toads, salamanders, and caecilians Hagfish, lampreys, and cartilaginous fishes

  30. Question 7 True or false? Vertebrates were able to harvest food by biting before jaws evolved. The hypothesis that tetrapod limbs evolved from fish fins has been supported by molecular evidence.

  31. Question 7 True or false? Vertebrates were able to harvest food by biting before jaws evolved. False The hypothesis that tetrapod limbs evolved from fish fins has been supported by molecular evidence. True

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