1. The Animal Kingdom Heterotrophic by ingestion
Motile; behaviorally complex
No cell walls
Structure based on extracellular proteins, especially collagen.
Characteristic cell junctions.
Similarities in ribosomal RNA

3. Evolutionary Trends in Body Plan
Symmetry:
None (sponges)
Radial (jellyfish, sea stars)
Bilateral (arthropods, vertebrates, etc.)
Cephalization: Evolution of a “head” with sensory and feeding organs.
Digestive system:
Ingestion into individual cells (sponges)
Gastrovascular cavity (blind sac) (jellyfish)
Digestive tract with mouth & anus (most other groups)
Body cavities: Evolution of a true coelom lined with peritoneum.

7. Sponges – Phylum Porifera
Simple body plan.
Choanocytes beat their flagella to create water flow.
Amoeboid cells feed by endocytosis.
Also review pores, osculum, and spicules

9. Phylum Cnidaria Only two cell layers – acoelomate.
Gastrovascular cavity (blind gut): opening acts as mouth and anus.
Radial symmetry.
Polyp and medusa body forms.

10. Classes of Cnidaria Anthozoa: sea anemones and corals (lack medusa)
Hydrozoa: Hydra and Portuguese man-of-war (colonial)
Scyphozoa: jellyfish (medusa dominates life cycle)

13. Portuguese Man-of-War Colonial hydrozoan, with stinging structures called nematocysts

14. Phylum Ctenophora – comb jellies
Like Cnidaria but with a complete gut (mouth and anus)

15. Protostomes vs. Deuterostomes
blastopore becomes the mouth
ventral nerve cord(s)
worms, insects, etc.
Deuterostomes
blastopore becomes the anus
dorsal nerve cord
sea stars, vertebrates

16. 2 main groups of protostomes
Lophotrochozoans – soft body, hydrostatic skeleton
Ecdysozoans – exoskeleton that molts

18. Platyhelminthes – the flatworms
simplest lophotrochozoans
acoelomate
gastrovascular cavity

19. Rotifers – small, structurally complex (complete digestive tract, ciliated structures)

20. Phylum Brachiopoda
Marine animals with a 2-part shell, similar to bivalve mollusks.
But they are NOT mollusks – they have a lophophore (ring of tentacles around the mouth.
Few living species; diverse in the Paleozoic

21. Annelida – segmented worms
True coelom
Segmented body
Soft flexible body wall.

22. Mollusca – the mollusks
coelomate
bilaterally symmetrical
body plan based on
muscular structure called a “foot”
“visceral mass” – internal organs
“mantle” – covers the visceral mass; secretes shell

23. Familiar mollusk groups
Bivalves: 2-part shell (clams, oysters)
Gastropods: snails, conchs, whelks, etc.
Cephalopods: octopus and squid (internal shell)

24. Ecdysozoans – animals with exoskeletons or tough cuticle