KEY TO MAJOR ANIMAL PHYLA
1. A. Body is soft with numerous pores, no appendages or obvious sensory organs. . . . . . . . . Phylum Porifera
B. Body is symmetrical with clear appendages or sensory organs . . . . . . . . . . . . . . . . 2
2. A. Body shows radial symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
B. Body shows bilateral symmetry or is worm-like or has a shell . . . . . . . . . . . . . . . . 4
3. A. Body is soft and smooth, mouth region is usually surrounded by tentacles . . . . . . . . . . . . . Phylum Cnidaria
B. Body is spiny . . . . . . . . . . Phylum Echinodermata
4. A. No gills, three or more appendages (if present) or no appendages (snakes not included) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Gills present or 2 pairs of appendages (including snakes) . . . . . . Phylum Chordata
5. A. Body includes jointed appendages with an exoskeleton . . . . . . Phylum Arthropoda
B. Body without jointed appendages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. A. Body is soft and flat, no segmentation . . . . . . . . . . . . . . . . Phylum Platyhelminthes
B. Body is not soft, flat, or does show segmentation. . . . . . .. . . . . . . . . . . . . . . . . . . . . 7
7. A. Body is worm-like with segments . . . . . . . . . . . . . . . . . . . . . Phylum Annelida
B. Body is not segmented . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. A. Body is slender, smooth, worm-like, but not flat . . . . . . . . . . . . . Phylum Nematoda
B. Body is covered by a shell or has tentacles or paired eyes or antennae. . . . . . . . . . . . . . . . . Phylum Mollusca