1. The Origin of Animal Diversity

2. What is an animal? Animals are:
Multicellular
Heterotrophic
Eukaryotic
Animals store energy as glycogen (not starch, as in plants)
Animals have nervous and muscular tissue
Animal cells do not have cell walls

3. The Origin of Animals
Most scientists believe that animals originated from a colonial protist (Choanoflagellate) which developed into a “proto-animal”

4. Phylogeny of the Animal Kingdom
Animals are divided into phyla (DKPCOFGS) based on evolutionary relationships and anatomical similarities
Organisms that split apart further back in the evolutionary tree (phylogeny) are the least related

5. Phylogeny of the Animal Kingdom
Division 1: Presence or Absence of Tissues
Parazoa vs. Eumetazoa
Parazoa do not have
true tissues (specialized
groups of cells)
Phylum Porifera
(sponges)
Eumetazoa have true
tissues
All other animals

6. Phylogeny of the Animal Kingdom
Division 2: Body Symmetry & Germ Layers
Radiata vs. Bilateria
Radiata have radial symmetry
top & bottom, but no left/right, no
anterior (head) or posterior (tail)
Phyla Cnidaria (jellyfish, corals,
anemones) & Ctenophora
(comb jellies)
Radiata also have only 2 germ layers:
- endoderm & ectoderm
Bilateria have bilateral symmetry
Top & bottom
Left & right
Anterior (head) & posterior (tail) end
Bilateria have 3 germ layers:
Endoderm, ectoderm, and mesoderm

7. Phylogeny of the Animal Kingdom
Division 3: Presence or Absence of a Coelom
Acoelomates vs. Coelomates
Acoelomates
do not have a coelom (body cavity
lined with mesoderm tissue)
Phylum Platyhelminthes
(flatworms)
Pseudocoelomates
Have a coelom (body cavity) that is not completely lined with mesoderm tissue
Phyla Rotifera (rotifers) and
Nematoda (roundworms)
Coelomates
Have a true coelom
(body cavity lined with mesoderm tissue)

9. Phylogeny of the Animal Kingdom
Division 4: Protostomes vs. Deuterostomes
Protostomes
The blastopore develops into the mouth
Phyla Mollusca (clams, snails), Annelida (segmented worms), & Arthropoda (crustaceans, insects, spiders)
Deuterostomes
The blastopore develops into the anus
Phyla Echinodermata (sea stars, sea urchins) & Chordata (lancelets, vertebrates)