Crash Course Chordata Questions Watch the video and answer the following questions: 1)How many species of vertebrates are under the phylum Chordata? 2)What do the branches on the evolutionary tree signify? 3)What is the most complex class in Chordata? 4)What are the 4 synapomorphic traits unique to Chordates? 5)What does the notochord become in humans? 6)What develops into the CNS? 7)In humans what does the pharyngeal slit tissue become? 8)When did these trains first begin to appear? 9)What are the 2 Chordate sub-phylum? 10)Do hagfish have a backbone? 11)What does Agnathans mean? 12)Sharks belong to which class? 13)Bony fish belong to which class? 14)How long ago did we think the Coelacanth became extinct? 15)What does tetrapod mean? 16)What is the first class of tetrapods? 16)Describe the structure of an amniotic egg. 17)Define ectothermic and name a class that shows this. 18)Define endothermic and name a class that shows this. 19)Name 3 traits unique to Mammals.