BIO2231 Chapter Notes -Axial Skeleton, Chordate, Somite
Document Summary
Notochord an elongated cartilaginous cellular cord enclosed in a sheath, which forms the axial skeleton of chordate embryos, jawless fishes and adult cellular chordates. Myotome the part of a somite destined to form muscle; the muscle group innervated by a single spinal nerve. Metamorphosis sharp change in form during post-embryonic development. Paedomorphosis retention of ancestral juvenile features in later stages of the ontogeny of descendants. Trimerous body in three main divisions, as in lophophorates and some deuteostomes. Endostyle mucus-secreting ciliated grooves in the floor of the pharynx of tunicates, cephalochordates, and larval jawless fishes useful for accumulating and moving food particles to the stomach. Ammocoetes the filter-feeding, land stage of lampreys. Pharyngeal slits filter-feeding organs found in non-vertebrate chordates and aquatic hemichordates. Gills respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. Ectothermic having a body temperature derived from heat acquired from the environment.
