1. Symmetry

2. Body Cavity

3. Stages of Animal Evolution

4. Sponges – Phylum Porifera
Sessile – does not move
Mostly marine
Multicellular – but has no tissues
No body symmetry
Gets nutrients through pores

5. Sponges

6. Sponge Anatomy

7. Phylum Cnidaria – stinging animals
Soft bodies with tentacles and stinging cells
Radial symmetry
One opening - both mouth and anus
Nerve net
Two cell layers – ectoderm and mesoderm
Polyp and medusa
Hydra, jelly fish, sea anemone

8. Cnidarians

9. Cnidarian Anatomy

10. Tentacles

11. Phylum Platyhelminthes - Flatworms
Flat bodies with bilateral symmetry
Nerve ladder with brain
3 cell layers – ectoderm, mesoderm and endoderm
Mostly parasitic
One opening
Planaria, flukes, tapeworms

12. Tapeworm

13. Planarian

14. Phylum Rotifera
Very small
Pseudocoelom
Crown of cilia for feeding

15. Phylum Nematoda - Roundworms
Bilateral symmetry
Tough outer covering - cuticle
Digestive cavity
Can be parasites
First to have body cavity – pseudocoelom
Ex. Roundworms, pinworms, heartworms

16. Nematodes

17. Phylum Annelida – Segmented Worms
Ringlike segmented bodies
Bilateral symmetry
Tubelike digestive tract
Organ systems
Setae on segments
Dorsal vein
Ventral nervous system
True Coelom
Ex. Earthworms, leeches

18. Annelids

19. Annelids

20. Phylum Mollusca – Soft bodied invertebrates
Soft bodies with shells
Move with muscular foot
Have a mantle that secretes the shell
Bilateral symmetry
True Coelom
6. Ex. Clams, scallops, squid, octopus, snails, slugs

21. Bivalves

22. Clam anatomy

23. Gastropods

24. Cephalopods

25. Phylum Arthropoda - Insects
Segmented
Jointed Appendages
Exoskeleton made of Chitin
Head, thorax, abdomen
Crustaceans – crabs, lobster, shrimps
Millipedes and Centipedes
Insects

26. Crustaceans

27. Insects

28. Metamorphosis

29. Echinoderms Deuterostome development – blastopore becomes the anus
Star fish, brittle stars, sea urchin

30. Sea Star

31. Echinoderms

32. Protostome and deuterostome development
Protostomes – determinate cleavage where early cells have predetermined fate
Deuterostomes – indeterminate cleavage where early cells can be the whole organism

33. Phylum Chordata Notochord, dorsal hollow nerve cord Gill slits
Deuterostome development
Vertebrates, lancelets, tunicates

34. Lancelets

35. Tunicate

36. Classes within Cnidaria
Hydrozoa – Hydra – alternates between medusa and polyp
Scyphozoa – medusa more prevalent
Anthozoa – sea anemones, coral (calcified skeleton)
Ctenophora – comb jellies

37. Classes within Platyhelminthes
Turbellaria – planarians – free-living, marine
Trematoda – flukes - parasitic
Cestoidea – tapeworms – parasitic

38. Classes within Annelida
Oligocheata – earthworms
Polychaeta – marine worms
Hirudinea - leeches

39. Classes within Arthropoda
Arachnida – spiders
Diplopoda – millipedes
Chilopoda – centipedes
Insecta – insects
Crustacea – lobsters, crayfish, crabs, shrimp

40. Classes within Echinodermata
Asteroidea – sea stars
Ophiuroidea – brittle stars
Echinoidea – sand dollar, sea urchin
Holothuroidea - sea cucumbers

41. Evolution of segmentation
Arthropods and annelids had a shared ancestor, but maybe not as close as once thought.
Hox genes in segmented animals will determine which organs will develop in each segment