how do these taxa relate?
DESCRIPTION
How do these taxa relate?. How do these embryological features relate to Deuterostomes and Protostomes ?. Haeckel 1874, proposed phylum “Chordata” and 3 subphyla: ______________ ______________ ______________ (includes Hagfish). Basal Deuterostomes. - PowerPoint PPT PresentationTRANSCRIPT
How do these taxa relate?
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How do these embryological features relate to Deuterostomes
and Protostomes?
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Basal DeuterostomesHaeckel 1874, proposed phylum “Chordata” and 3 subphyla:
______________
______________
______________ (includes Hagfish)
Basal DeuterostomesHypothesis that vertebrates and these “protochordates” share common ancestor provides impetus for study
What features do these larvae share?
How are they unique?
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
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
Basal DeuterostomesHemichordata (acorn worms)
2-3 possibilities for taxonomic placement:
*
*
* http://www.geol.umd.edu/~tholtz/G331/lectures/331grapt.html
Basal DeuterostomesFeatures 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
UrochordatesFilter-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
UrochordatesFilter-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
UrochordatesFilter-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
Cephalochordates*
2 genera:*Branchiostoma *Asymmetron
*
http://comenius.susqu.edu/bi/202/Animals/DEUTEROSTOMES/cephalochordata/uwinnipeg-Lancelet.jpg
CephalochordatesBrief survey of systems:
Musculature and integument:
*
*
*
*
*
*
Advantages of thin skin?
CephalochordatesPharyngeal slits:
Exit to …
Filtered water leaves via …
…minimizes respiratory usefulness
Cephalochordates“Skeletal” Notochord:
__________________more apropo
*
*
Notochord to rostrum adaptation for …
Other “skeletal” elements include:
CephalochordatesNervous system
*
*(38 vs. 10-18)
Spinal nerves with ___________ onlyconducting sensory (afferent) signals to spinal cord and brain
*
CephalochordatesDigestive 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 …
CephalochordatesCirculatory system
*
*
*
Cecal vein assists by pumping to sinus
CephalochordatesExcretory system
*
Cryptopodocytes (between protonephridia and podocytes)
*
*
Wastes leave via…
CephalochordatesReproductive system
*
Gonads (ovaries and testes)empty sex cells (eggs and sperm) into …
CephalochordatesCompare - Contrast
No
No
No
2 instead of 3
2 layered skin (1 cell thick)
No
Greatly reduced coelom
BUT many synapomorphies
Origin of craniates