1. Animal Phyla

2. It all started with the tiny little ancestral protist.
First evolutionary milestone:
Multicellularity!!
First multicellular animal was probably the…..

3. Phylum: Porifera
Multicellular
Lack “true” tissues
Sponges

4. Phylum: Cnidarians Next evolutionary milestone: TRUE TISSUES!!!
Diploblastic (2 tissue layers):
Ectoderm & Endoderm
Polyps (sea anemones) or medusas (jellyfish)
Radial Symmetry: symmetry around a central axis
Examples: hydras, jellyfish, coral

5. Phylum: Platyhelminthes
Evolutionary Milestone:
Triploblastic (3 tissue layers):
Ectoderm
Mesoderm
Endoderm
Bilateral Symmetry
Acoelomate – without body cavity
Cephalization: sense organs at the anterior end
Examples: flatworms - planaria, tapeworms, flukes

6. Phylum: Nematoda “Pseudocoelomates” Examples: Evolutionary Milestone:
A space between the tissues called a:
“Coelum” but…..
Nematodes are acually:
“Pseudocoelomates”
Cavity is just between the 2 tissue layers.
Examples:
roundworms – pinworms, hookworms

7. Protostome vs Deuterostome?
This next step isn’t really a “milestone,
… it’s more like a “fork in the river”.
Blastopore: the first opening into embryo, it will become mouth in protosomes and the anus in deuterosomes.
Protostome- Coelom originates
from a cell mass.
Deuterostome- Coelom originates
from a digestive tube.
The next several Phyla are all protostomes…..

8. First Protostome: Phylum: Mollusca
A true coelom!
(albeit reduced)
Soft bodied animals (slugs, clams, snails, squids, octopuses
3 main body parts – muscular foot, visceral mass, mantle
Hard shells made of calcium carbonate
Organs not really compartmentalized.

9. Phylum: Annelids Evolutionary milestones: Segmentation!
Allows for more compartmentalization and specialization
Also a true coelom!
A split within the mesoderm provides “mesentaries” from which organs can suspend.
Segmented worms (earthworms, leeches)
(also have a closed circulatory system…. More about that to come…)

10. Phylum:Arthropods Evolutionary Milestone: Jointed Appendages!!
Insects, arachnids, millipedes, centipedes, crustaceans
Reminders:
Arthropods (as well as annalids) are segmented.
We are still on the branch of protostomes.
…but now let’s go back to the dueterostome branch:

11. First Deuterostome: Phylum: Echinodermata
Sea stars and sea urchins
Coelomates with secondary radial anatomy
Larvae: bilateral
Adults: radial
Water vascular system used for moving, feeding, and gas exchange
Actually have a type of internal skeleton.
This leads us to our last Phylum:

12. Phylum: Chordata Lancelets, tunicates, vertebrates
Coelomates with notochord
Dorsal, hollow nerve cord
Hagfish 
Chondrichthyes (Sharks/Rays) 
Osteichthyes (Bony Fish) 
Amphibians (Frogs, Salamanders) 
Reptiles (Snakes, Turtles, Crocs) 
Aves (Birds) 
Mammals
(Mice, dogs, cats, chimps, you, me)

13. Body plans Asymmetry Radial symmetry – central axis
Bilateral symmetry – distinct left and right sides
dorsal (back side) ventral (belly side) anterior (head) posterior (tail)

14. Terms Zygote – fertilized egg Cleavage
Blastula (hollow ball of cells) pinches inward to form three GERM LAYERS:
Ectoderm
Mesoderm
Endoderm
Blastopore: opening into gastrula, it will become mouth in protosomes and the anus in deuterosomes