BIOL 1503 Chapter : Chordata
Document Summary
Figure 34. 2 & 34. 2a & 34. 2b: myxini & petromyzontida grouped together, fish grouped together. Phylum chordata: know the 4 hallmarks, notochord, dorsal, hollow nerve cord, pharyngeal gill slits, muscular, postanal tail, fig 34. 3. 2 invertebrate groups: urochordata: tunicates fig 34. 4, hallmarks in larvae, cephalochordata: lancets fig 34. 5, hallmarks in adult, myomeres, marine suspension feeders. Phylum chordata: subphylum vertebrata, living endoskeleton of cartilage/bone, protect organs, attachment site for muscles, pancreas & liver, paired limbs for most: facilitated capturing/eating prey, protected brain case, closed circulator system with cardiac muscle. Evolution of vertebrates: the brain and the cranium evolved first in the vertebrate lineage, followed by the vertebral column, the jaws, ossified skeleton, and paired appendages evolved later, 2 superclasses, superclass agnatha=jawless, superclass gnathostomata=jawed vertebrates. Jawless vertebrates: circular mouth, lampreys (parasite) & hagfish (scavenger, cartilaginous; notochord persists, no paired fins, more diverse in fossil record than today, oldest living group of vertebrates, fig 34. 9. Superclass gnathostomata: chondrichtyes: elasmobranches: sharks, skates, and rays.
