Sam Houston State University
Sam Houston State University: Chordate Characteristics
This site describes the characteristics of Chordates. There are also examples of two groups that show an affinity toward the phylum Chordata but do not actually exhibit the characteristics. This site also describes the history of the...
Other
Jeff's Coral Reef Gallery: Tunicates
This excellent underwater photo of a tunicate includes a short but informative description of tunicates in general (also known as "sea squirts").
California Academy of Sciences
California Academy of Sciences: Echinoderm Webpage
Resource provides a brief overview of echinoderms. Includes pictures and links for more information.