How do these taxa relate?

How do these embryological features relate to Deuterostomes and Protostomes?

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

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?

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?

Basal Deuterostomes _________________ (acorn worms) Bateson 1884, proposed Hemichordata as a subgroup of _____________

Basal Deuterostomes Hemichordata (acorn worms) 2-3 possibilities for taxonomic placement: *

Basal Deuterostomes Features shared by echinoderms and hemichordates: *Similar ciliated larvae (________ and _______) * Features linking to chordates: *

Urochordates Filter-feeding marine organisms divided into 3 classes: *____________ (tunicates or “sea squirts”) * Adults respire and feed using:* __________sends food to _________, then __________

Urochordates Filter-feeding marine organisms divided into 3 classes: *__________________ Free-swimming plankton Large mucus tunic bwttf/larvatian1p2_x50.jpg

Urochordates Filter-feeding marine organisms divided into 3 classes: *____________ (“salps”) Alternation of generations (free-living and colonial) No notochord… so why in phylum chordata?

Cephalochordates * 2 genera: *Branchiostoma *Asymmetron * Lancelet.jpg

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

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

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

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

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 …

Cephalochordates Circulatory system * Cecal vein assists by pumping to sinus

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

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

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

Origin of craniates