Animal Kingdom
Animal Kingdom tests classification, body plan, symmetry, coelom, segmentation, notochord and diagnostic features of major phyla.
Core rules
- Porifera are cellular-level, mostly asymmetrical sponges with choanocytes and spongocoel.
- Cnidaria show radial symmetry and cnidoblasts; Platyhelminthes are acoelomate flatworms.
- Aschelminthes are pseudocoelomate roundworms; Annelida show true coelom and metameric segmentation.
- Arthropoda are the largest phylum with jointed appendages and chitinous exoskeleton.
- Echinodermata have water vascular systems and are deuterostomes; Chordata have a notochord, dorsal hollow nerve cord and pharyngeal gill slits at some stage.
Worked example
An organism has jointed legs, a chitinous exoskeleton and segmented body regions. It is placed in Arthropoda, not Annelida, because Annelida have soft segmented bodies with setae and no jointed exoskeleton. The reasoning uses diagnostic features rather than habitat: jointed appendages and chitinous exoskeleton are arthropod traits.
Traps
- Coelom type is a key character: acoelomate, pseudocoelomate and coelomate differ.
- Sponges lack true tissues and organs.
- Echinoderms are not radially symmetrical as adults in the same way as cnidarians; larvae are bilateral.
- Notochord is not the same as vertebral column.