BIO325H5 Lecture Notes - Lecture 1: Muscular Hydrostat, Axial Skeleton, Hagfish
Document Summary
Notochord of chordates as a hydrostatic* axial skeleton*kier mentions this under additional examples": phylum name chordata** --comes from their possession of a notochord; chordates are diagnosed by certain body features shared by all species in the phylum: 1. dorsal tubular (hollow) nerve cord (dorsal to the digestive tract)*** 4. circulation occurs from the heart forward in a ventral vessel and then up around the pharynx and rearward in a dorsal vessel*** 6. ---and at some time in their development all chordates have a notochord, a long cylindrical tube bounded by connective tissue, surrounding a core of muscle cells and fluid; this is also functioning as a hydrostatic structure a muscular hydrostat. Hagfish, lampreys, jawless fishes are a class within the subphylum vertebrata the most primitive of fishes. ***contrast with annelids: ventral solid nerve cord; anterior blood flow in dorsal vessel. In addition, notochords may adjust function by means of dynamically variable mechanical properties (long et al. , 1998).
