l20. basal chordata
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Chordata: origins and body plan
Basic Chordate Body Plan4 major features of Chordata
notochorddorsal hollow nerve
pharyngeal slits post-anal tail
Basic Chordate Body Plan4 major features of Chordata
notochorddorsal hollow nerve
pharyngeal slits post-anal tail
These are synapomorphies for chordates
Urochordata: tunicates
Urochordates show chordate characters in the larva
1. Notochord2. Dorsal hollow nerve3. Pharyngeal slits
Urochordate Larvae
very young larva
late larvalstage
Cephalochordata:lancelets
notochord dorsal hollow nerve
many pharyngeal slits
Cephalochordatatail cross-section
dorsal hollow nerve
notochord
Hemichordata
Hemichordate
1.
2.
3.
1. Pharyngeal slits2. Dorsal hollow nerve, notochord3. Postanal tail, neural crest cells, vertebrae
Major Groups of chordates we will visit in coming lectures Trends in early Chordate & Vertebrate Evolution
1. Increased cephalization2. Increased activity levels3. Increased tendency toward predatory life-style
Lamprey Larval Lamprey
Vertebrate Body Plan
1. Notochord2. Dorsal hollow nerve, brain, eyes3. Paired kidneys4. Pharyngeal slits5. Heart, aortic arches, dorsal aorta6. Segmented body organization
Vertebrate Body Plan
Lamprey: bloodsucking basal vertebrate!!
-No bone, no jaws-Has pharyngealslits, notochord,dorsal hollow nerve,post-anal tail
Hagfishes: scavengers on dead animal carcasses
-No bone, no jaws-Has pharyngeal slits, notochord,dorsal hollow nerve, post-analtail