2. p. 21What Is a Vertebrate?
- F. Harvey Pough, F. Harvey PoughProfessor Emeritus, Rochester Institute of Technology
- William E. Bemis, William E. BemisProfessor of Ecology and Evolutionary Biology and Faculty Curator of Ichthyology, Cornell University
- Betty McguireBetty McguireSenior Lecturer, Cornell University
- , and Christine M. JanisChristine M. JanisProfessor Emerita of Biology, Brown University, USA, Honorary Professor of Earth Sciences, University of Bristol, UK
Abstract
This chapter explains that vertebrates belong to the phylum Chordata, which along with the echinoderms and the hemichordates comprise the Deuterostomia. Deuterostomes and protostomes are the subdivisions of the more complex animals with bilateral symmetry and bodies that develop from three layers of tissue. The chapter looks at non-chordate deuterostomes, which are all small marine animals that are united by the presence of pharyngeal slits at some stage of their lives. The main characteristic of all chordates is the notochord, which is a dorsal stiffening rod to which muscles attach and are seen at some point of development in all chordates. The chapter shows that the notochord is a transient structure in most vertebrates. This is replaced during embryonic development by the vertebral column.
