1. The Wonderful World of Animals!

2. What is true about ALL animals? They are eukaryotic They are multicellular They are heterotrophs (If they make their own food, they are not animals) They lack cell walls They possess nervous tissue and muscle (at least myosin and actin in some form) Generally, they reproduce sexually

3. How do we begin to classify animals? 1. How many “layers” do they have? Uniblastic Diploblastic: only an endoderm and ectoderm Triploblastic: endoderm, mesoderm, ectoderm – Vast majority of animal phyla are triploblastic

4. How do we begin to classify animals? 2. What type of “symmetry” do they have? Radial symmetry: best for animals that don’t have to move much…

5. How do we begin to classify animals? Bilateral symmetry: great for animals that need to move fast With bilateral symmetry came “cephalization” – The movement of sensory organs and nervous tissues in a head at the anterior of the animal – Good to have this all up front…it’s what encounters a new environment 1 st

6. How do we begin to classify animals? With bilateral symmetry also came “segmentation” Developing a series of ‘body units’ (like an earthworm) Allowed animals to develop specialized parts…legs, wings, antennae

7. How do we begin to classify animals? 3. What do their body cavities look like? Coelom: “body cavity” A. Acoelomate: no body cavity; everything between body wall and internal organs is filled with mesenchyme Flatworm

8. Body Cavities B. Pseudocoelomate: mesoderm lines the inside of the body wall but NOT the internal organs Ascaris: A Parasitic Roundworm

9. Body Cavities C. Coelomate: Both inside body wall and internal organs are lined by mesoderm “peritoneum”

10. Phylum Porifera Sponges! – Uniblastic – If any symmetry at all, it is radial – Sessile

11. Phylum Cnideria Usually radial symmetry Diploblastic: Has 2 cell layers: endoderm and ectoderm Blind gut: mouth and anus are the same opening All are carnivores; possess nematocysts Jellyfish, sea anemones, corals

12. Ctenophores (Comb Jellies) Complete guts (separate mouth and anus) Usually radial symmetry Diploblastic: Has 2 cell layers: endoderm and ectoderm Sticky tentacles, not nematocysts

13. Protostomes vs. Deuterostomes Stome: Mouth Proto: First Deutero: Second Protostome: Mouth forms 1st from blastopore Deuterostome: Anus forms 1 st from blastopore, mouth arises elsewhere 2 nd

14. What is a blastopore anyway? Spot in the embryo where vegetal pole folds inward This is a sea urchin embryo…Is it a protosome or a deuterostome?

15. Comparison/Contrast Protostomes Triploblastic Bilateral symmetry Cephalized (anterior brain) Blastopore becomes the MOUTH VENTRAL nervous system Deuterostomes Triploblastic Bilateral symmetry Cephalized (anterior brain) Blastopore becomes the ANUS DORSAL nervous system

16. Protostomes (many phyla) Lophotrochozoans Grow by adding size Flatworms (Platyhelminthes) Rotifera Annelids (Segmented worms) Mollusks Ecdysozoans Grow by molting Nematodes (cuticles) Arthropods (segmented external skeleton) – Crustaceans – Insects – Arachnids

17. Those who grow by adding size Platyhelminths (flatworms)

18. Those who grow by adding size Rotifers

19. Those who grow by adding size Annelids (includes the earthworm)

20. Circulatory System of an Annelid The circulatory system is CLOSED Blood is enclosed within vessels and does not mix with other body fluids As you might expect, this is also characteristic of all vertebrates

21. Those who grow by adding size Mollusks From snails to clams to octopus to giant squid

22. Body plan of a mollusk Visceral mass, mantle, & foot

23. Circulatory System of a Mollusk The circulatory system is OPEN Arthropods will be like this too. Blood mixes with other body fluids

24. Those who grow by molting These animals have an “exoskeleton” Nematodes (Roundworms) – External cuticle: flexible but unsegmented Arthropods: Segmented external skeleton – “Jointed foot”

25. Arthropods Crustaceans Insects Arachnids

26. Crustaceans Marine animals 3 body segments Head, thorax, and abdomen

27. Insects 1.4 MILLION species

28. Arachnids Scorpions and spiders

29. On to Deuterostomes Two major classifications 1. Echinoderms 2. Chordates – Characterized by dorsal notochord which becomes the vertebrae in Vertebrates

30. Echinoderms Starfish, sand dollars, sea urchines

31. Chordates Features at some point during development – Pharyngeal slits – A dorsal hollow nerve cord – A dorsal supporting rod (notochord) – A tail extending past the anus – A ventral heart

32. Relationship of Chordates We’ll draw a picture here!

33. How the Circulatory Systems Differ Among the Chordates

34. Fish

35. Lungfish

36. Amphibians

37. Crocodile

38. Reptiles

39. Birds and Mammals