Chapter 34 Origin and Evolution of Vertebrates o In the past many animals had spikes or armor that protected them from predators o Vertebrates aminals that have a backbone Chordates have a notochord and a dorsal hollow nerve cord o Chordates bilarian animals o Derived characters of chordates Notochord flexible rod that goes from head to tail between digestive tube and nerve cord Large fluid filled cells in stiff firbous tissue Present in all chordate embryoes and some adult chordates Provides skeletal support In most vertebrates a skeleton develops around the notochord Dorsal hollow nerve fchord Develops from a plate of ectoderm that rolls around itself to make a nerve cord o Develops into the central nervous system brain and spinal cord Pharyngeal slits or clefts series of pouches separated by grooves that form along the sides of the pharynx Develop into slits that allow water to enter the mouth and exit the body without entering the digestive system Some develop into gills Develop into parts of the ear and other head and neck structures Muscular post anal tail Helps propel aquaticc species in water o Lancelets blade like basal group of chordates Notochord hollow nerve cord pharegneal slits and a post anal tai Craniates are chordates that have a head Vertebrates are craniates that have a backbone
View Full Document
Unlocking...