Zoology 250 (2002)

Cladogram for KINDOM ANIMALIA (=Metazoa)


Modified from Tree of Life for Kingdom Animalia (after Ruppert & Barnes 1994 p. 1052).


     ========================================== Porifera (sponges)
     |
     |      =================================== Cnidaria (jellyfish, anemones, corals, etc.)
     |      |
     |      |  ================================ Ctenophora (comb-jellies)
     |      |  |
     |      |  |       ======================== Platyhelminthes (flatworms, tapeworms,etc.)
     |      |  |       |
     |      |  |       |  =(branch uncertain)== Aschelminthes (nematodes, rotifers,etc.)
     |      |  |       |  |
<<=M=|      |  |   =P==|  |   ================= Nemertea (ribbon worms) 
     |      |  |   |   |  |   |
     |      |  |   |   |  |   |        ======== Mollusca (snails, clams, squids, etc.)
     |  =E==|  |   |   ===|   |  ======|
     |  |   |  |   |      |   |  |     ======== Sipuncula (peanut worms)
     |  |   |  |   |      =C==|  |
     |  |   |  |   |          |  |        ===== Annelida (segmented worms)
     |  |   |  |   |          ===|     ===|
     |  |   |  |   |             |  ===|  ===== Pogonophora (beard worms, vent worms)
     |  |   ===|   |             |  |  |
     |  |      |   |             ===|  ======== Echiura (proboscis worms)
     |  |      |   |                |
     ===|      |   |                |  ======== Onychophora (velvet worms)
        |      |   |                ===|
               =B==|                   ======== Arthropoda (insects, spiders, crabs, etc.)
        |          |
                   |   ======================== Chaetognatha (arrow worms)
        |          |   |
                   =D==|  ===================== lophophorates (bryozoans, brachiopods, etc.)
        |              |  |
                       |==|     =============== Echinodermata (starfish, urchins, etc.)
        |                 |  ===|
                          ===|  =============== Hemichordata (acorn worms, pterobranchs)
        |                    |
                             ================== Chordata (sea squirts, vertebrates, etc.)
        |
        = = =(phyla of uncertain affinity)= = = Placozoa, Monoblastozoa, Rhomobozoa, Orthonectida


TRAITS SUPPORTING EACH CLADE (** plesiomorphic- a primitive state, not unique to clade):
M= METAZOA:
a) true multicellularity (no endoderm, no true gut)
b) radial symmetry**
c) monociliated cells**
d) radial, indeterminate cleavage
e) blastula stage larva
f) diplosome**
g) type IV collagen


E= EUMETAZOA:
a) true tissues
b) diploblastic organization
c) gastrula stage
d) blind gut (no anus)


B= BILATERIA:
a) bilateral symmetry
b) cephalization
c) triploblastic organization (extensive mesoderm)
d) organ-system level of organization
e) protonephridia
P= PROTOSTOMIA:
a) spiral, determinate cleavage
b) mesoderm from mesenchyme cells
c) fate of first derm cell set at 5th cleavage
d) mouth (and sometimes anus) from blastopore
e) multiciliated cells
f) trochophore-like larva


C= COELOMATE PROTOSTOMES:
a) 4D cell is entomesoblast cell
b) coelom via schizocoely
c) complete gut (anus present)**


D= DEUTEROSTOMIA:
a) radial, indeterminate cleavage**
b) mesoderm from epithelial cells
c) coelom via enterocoely
d) blastopore yields anus
e) tripartite coelom & body plan
f) monociliated cells**



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Copyright © 2002 by A. Richard Palmer. All rights reserved.
(revised Jan. 6, 2002)