by Aaron G. Filler, MD, PhD
Figure 7- 1 Metazoan Systematics:
Relationships among the multicellular animals. The Bilateria share bilateral (right/left) symmetry as opposed to branching (sponges) or radial symmetry (jellyfish). The Bilateria are divided into Protostome and Deuterostome groups based on which end of the embryo turns into the mouth. The vertebrates are deuterostome bilaterians, but our group includes some of the very simple animals shown in the diagram.
A - Redrawn, modified protostome, deuterostome developmental sequence after Kardong (2005) Vertebrates: 4th ed, McGraw-Hill
B- Redrawn, modified cladogram after: Kardong (2005) Vetebrates: 4th ed, McGraw Hill
B - Redrawn, modified animal figures of Porifera and Nematoda, after: Cleveland Hickman (1973) Biology of the Invertebrates, 2nd Edition, Mosby Elsevier
B - Redrawn, modified animal figures of Cnidaria and Platyhelminthes, after: Cleveland Hickman, Integrated Principles of Zoology (1955), Mosby
B - Redrawn, modified animal figure of squid after: Drew, G.A. (1911) Sexual attraction in the Squid. J. Morph 22:327-359
B - Redrawn, modified animal figures of Arthropoda, Echinodermata, Hemichordata, and Chordata after: Liem et al (2001), Functional Anatomy of the Vertebrates, An Evolutionary Perspective, 3rd edition.