BIO 2135 Lecture Notes - Lecture 4: Autapomorphy, Neural Tube, Genitourinary System
Document Summary
Hemichordates do not have a notochord (have a stomochord) Called hemichordates because they only have half (2/4) of chordate characteristics. Although their pharyngeal slits and nerve chord are used differently. Stomochord proboscis complex creates high blood pressure that is ltered by the glomerulus. Hence new way to lter the ood. Body divided into: protocoel (proboscis), mesocoel (collar), and metacoel (trunk) Metacoel is divided into: branchiogenital region, hepatic region, and intenstinal region. Stomochord: keeps the mouth open (because there is no skeleton there) and it provides rigid support to anterior end of the worm. There is a heart that pumps blood. As heart pumps blood it pushes against the stomochord. Pinches down on the blood vessel pushing blood through it kind of like a peristaltic pump. The pinching of the blood vessel not only propels blood through the body but also creates blood pressure.