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How do these taxa relate?. How do these embryological features relate to Deuterostomes and Protostomes?

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Presentation on theme: "How do these taxa relate?. How do these embryological features relate to Deuterostomes and Protostomes?"— Presentation transcript:

1 How do these taxa relate?

2 How do these embryological features relate to Deuterostomes and Protostomes?

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

4 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?

5 Basal Deuterostomes _____________ (sea stars and allies) In fossil record from Cambrian to present ____ classes… today representatives of ___ 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

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

7 Basal Deuterostomes Hemichordata (acorn worms) 2-3 possibilities for taxonomic placement: * http://www.geol.umd.edu/~tholtz/G331/lectures/331grapt.html

8 Basal Deuterostomes Features shared by echinoderms and hemichordates: *Similar ciliated larvae (________ and _______) * Features linking to chordates: * http://scaa.usask.ca/gallery/lacalli/images/tornaria3.jpg http://scaa.usask.ca/gallery/lacalli/images/cucumber5.jpg

9 Urochordates Filter-feeding marine organisms divided into 3 classes: *____________ (tunicates or “sea squirts”) * Adults respire and feed using:* __________sends food to _________, then __________ http://www.youtube.com/watch?v=mecEpYS2Bgw

10 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

11 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

12 Cephalochordates * 2 genera: *Branchiostoma *Asymmetron * http://comenius.susqu.edu/bi/202/Animals/DEUTEROSTOMES/cephalochordata/uwinnipeg- Lancelet.jpg

13 Cephalochordates Brief survey of systems: Musculature and integument: * Advantages of thin skin?

14 Cephalochordates Pharyngeal slits: Exit to … Filtered water leaves via … …minimizes respiratory usefulness

15 Cephalochordates “Skeletal” Notochord: __________________more apropo * Notochord to rostrum adaptation for … Other “skeletal” elements include:

16 Cephalochordates Nervous system * * (38 vs. 10-18) Spinal nerves with ___________ only conducting sensory (afferent) signals to spinal cord and brain *

17 Cephalochordates Digestive system * Buccal cirri coarse filter, monitor water Vestibule bounded by oral hood and velum * Ciliated cells create … Moves to midgut to mix with … Intestinal cecum …

18 Cephalochordates Circulatory system * Cecal vein assists by pumping to sinus

19 Cephalochordates Excretory system * Cryptopodocytes (between protonephridia and podocytes) * Wastes leave via…

20 Cephalochordates Reproductive system * Gonads (ovaries and testes) empty sex cells (eggs and sperm) into …

21 Cephalochordates Compare - Contrast No 2 instead of 3 2 layered skin (1 cell thick) No Greatly reduced coelom BUT many synapomorphies

22 Origin of craniates


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