1. “Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts some of them interesting or curious but making no meaningful picture as a whole.” Dobzhansky 1973

2. How do these taxa relate? Radiata Ecdysozoa Deuterostomata Bilateria Lophotrochozoa Protostomata

3. How do these embryological features relate to Deuterostomes and Protostomes? Radial cleavage Spiral cleavage Blastopore => mouth Blastopore => anus Enterocoely Schizocoely

4. Basal Deuterostomes Haeckel 1874, proposed phylum “Chordata” and 3 subphyla: __________________ __________________ (includes Hagfish)

5. Basal Deuterostomes Hypothesis that vertebrates and these “protochordates” share common ancestor provides impetus for study What features do these larvae share? How are they unique?

6. Basal Deuterostomes ____________ (sea stars and allies) In fossil record from Cambrian to present 20 classes… today representatives of 5 Unique features: * So why would they be considered “more closely related” than other marine invertebrates… say clam worms? http://www.palaeos.com/Invertebrates/Deuterostomia/Homalozoa/Images/Syringocrinus.gif

7. Basal Deuterostomes __________________ (acorn worms) * Bateson 1884, proposed Hemichordata as a subgroup of Chordata http://www.wildsingapore.com.sg/wildfilms/blog/050402cjd2070m3a.jpg http://coris.noaa.gov/glossary/hemichordate_186.jpg

8. Basal Deuterostomes Hemichordata (acorn worms) 2-3 possibilities for taxonomic placement: *Sister group to… *Sister group of… *Undetermined status (incertae sedis) http://www.geol.umd.edu/~tholtz/G331/lectures/331grapt.html

9. Basal Deuterostomes Features shared by echinoderms and hemichordates: *Similar _____________ (bipinnaria and tornaria) *Muscle proteins *Nervous system structure Features linking to chordates: *____________ system * http://scaa.usask.ca/gallery/lacalli/images/tornaria3.jpg http://scaa.usask.ca/gallery/lacalli/images/cucumber5.jpg

10. Urochordates Filter-feeding marine organisms divided into 3 classes: *___________ (tunicates or “sea squirts”) Larva are free-swimming but short-lived Non-feeding larva metamorphosis Adults respire and feed using:* Endostyle sends food to esophagus, then stomach http://www.youtube.com/watch?v=mecEpYS2Bgw +/- phototaxis?

11. Urochordates Filter-feeding marine organisms divided into 3 classes: * Free-swimming plankton Large mucus tunic http://homepage.mac.com/a.shiroza/pictures/planktons/ bwttf/larvatian1p2_x50.jpg

12. Urochordates Filter-feeding marine organisms divided into 3 classes: *___________ (“salps”) Alternation of generations (free-living and colonial) No notochord… so why in phylum chordata? http://www.youtube.com/watch?v=KRVdGam3G2U&NR=1 http://chemistry.csudh.edu/faculty/jim/cantamar/salp.jpg

13. Cephalochordates “Amphioxus” or “Lancelets” 2 genera: *Branchiostoma *Asymmetron Marine organisms found in coarse, sandy substrates http://comenius.susqu.edu/bi/202/Animals/DEUTEROSTOMES/cephalochordata/uwinnipeg- Lancelet.jpg

14. Cephalochordates Brief survey of systems: Musculature and integument: Mostly all trunk Metamerism (myomeres) Myoseptum Muscle fibers uninucleate Single cell layer epidermis Thin dermis Advantages of thin skin?

15. Cephalochordates Pharyngeal slits: Exit to an internal chamber (___________) Filtered water leaves via… Slow moving water, high metabolic demands of cilia cells, and vasculature in collagen minimizes respiratory usefulness

16. Cephalochordates “Skeletal” Notochord: “Muscular” notochord more apropo Muscular discs encased in sheath __________ ___________ rather than neurons Notochord to rostrum adaptation for burrowing Other “skeletal” elements include: fibrous rods in…

17. Cephalochordates Nervous system 2 part brain rather than 3 Many cranial nerves (38 vs. 10-18) Spinal nerves with dorsal root only conducting sensory (________) signals to spinal cord and brain ________________, __________________ and ________________

18. Cephalochordates Nervous system Why such a small brain? * * Abundant chemoreceptors on cirri and tentacles… WHY? Tail also abundant

19. Cephalochordates Digestive system ______________ ______ _____ coarse filter, monitor water _________ bounded by oral hood and velum Mouth opens to _____ _____ ______ picks up “chunks” http://www.uta.edu/studentorgs/pdsa/chordata.htm

20. _____________ create flow and mucus Moves to midgut to mix with enzymes Intestinal cecum (“____________”)

21. Cephalochordates Circulatory system No ______ No ________ No _______________ Sinus venosus Cecal vein assists by pumping to sinus

22. Cephalochordates Excretory system No _____________ ______________ (between protonephridia and podocytes) Pedicels surround ___________ __________ extend to nephridial tubule Wastes leave ____________

23. Cephalochordates Reproductive system _____________ Gonads (ovaries OR testes) empty sex cells (eggs OR sperm) into atrium, leaving via atriopore

24. Cephalochordates Compare - Contrast limited cephalization No ________________________ 2 instead of 3 brain parts 2 layered skin (1 cell thick) No __________________ Greatly reduced coelom BUT many synapomorphies

25. Origin of craniates

26. So how do we get a vertebrate from an invertebrate? From annelid or arthropod-like ancestor?!? From a ribbon worm ancestor?!? From a sea cucumber?!? From an inverted acorn worm?!? http://www.stanford.edu/~bhackett/monterey-2005-02-04/images/california-sea-cucumber.jpg http://www.idratherbewriting.com/wp- content/uploads/2007/07/grasshopper.jpg http://northislandexplorer.com/worms/orangeribbonwork.jpg http://www.bethel.edu/~johgre/bio114d/image s/Lower%20Verts/oAcornWorm.jpg