What is an Animal? Chapter 24

1. What is an Animal?Chapter 24 Animal Movie (15 min)

2. 24-1 Animal Characteristics • Eukaryotic • Multicellular • Heterotrophic • Mobile at some stage

3. Support • Support • Invertebrates – lack backbones • May have external skeleton- exoskeleton • May have internal skeleton – endoskeleton • Vertebrates – have backbones & endoskeleton

4. Animal Development • Most have Sexual Reproduction • Egg + Sperm = Fertilization • Can be internal or external fertilization • Forms a single celled zygote • Undergoes cell division during cleavage to form two cells • Hermaphrodites – have both male and female reproductive parts

5. Cell Division • Once it is two cells, now called an embryo • Cells keep dividing to form a hollow ball called a blastula • Cells begin to fold inward to form a gastrula, this forms an outer layer (ectoderm) and an inner layer (endoderm) • Ectoderm develops into skin and nervous tissue • Endoderm develops into digestive track and organs associated with digestion

6. Cell Division

7. Gastrulation

8. Tissue Development • Endoderm – inner layer that develops into digestive organs and the lining of digestive tract • Mesoderm - middle layer that develops into muscles, circulatory system, excretory system, and in some respiratory system • Ectoderm – outer layer that develops into nervous tissue and skin • Sea Urchin - Blastula

9. Germ Layer Development

10. 24-2 Animal Body Plans

11. See Page 699!

12. Symmetry View of the left side of a bilaterally symmetrical animal.  Drawing by John Norton.

13. Symmetry • Asymmetry – no symmetry • Ex. Sponges

14. Radial Symmetry • Radial – can be divided along any plane through a central axis • Examples: Hydra and Jellyfish

15. Bilateral Symmetry • Bilateral – can be divided down its length into mirror images • Examples: Humans and dogs

16. Body Plans • Acoelomate – has three body layers, but no cavity • Example – Flatworm

17. Acoelomate

18. Pseudocoelomate • Pseudocoelomate – have three body layers, with a fluid-filled body cavity between the endoderm and mesoderm layers • Example: Roundworms

19. Pseudocoelomate

20. Coelomate • Coelomate – have three body layers, with a fluid-filled body cavity within the mesoderm layer • Examples – earthworms, insects, fish

21. Coelomate

22. Protostome vs. Deuterostome • Protostome animals develop the mouth first • Examples include earthworms and insects • Deuterostome animals develop the anus first • Examples include echinoderms and vertebrates

23. Chapter 24.3 Sponges, Cnidarians

25. Phylum Porifera Sponges: • Invertebrates • Sponges can live to be 100+ years old. Yellow Tube Sponge

26. Porifera Body Structure • Asymmetrical • No Tissues (ecto-, endo-, mesoderm) • Just two layers of cells with a jelly-like substance in between • Porus

27. Porifera Body Structure • Pore cells: These surround the pores on the outside of the sponge. The pores are where water and food enter the sponge • Epithelial cells: These are the outer ‘skin’ of a sponge. These cells can contract to close the pores, if needed • Collar cells: These line the inside of the sponge. These cells have flagella that cause the current of water

28. Sponge Anatomy http://lcmrschooldistrict.com/roth/Biology_animate/Ch26/ActiveArt/

29. Porifera Body Strurcture Spicules: Between sponge cells • Not cells • Make up the ‘skeleton’ support system • Sponge structure video - sponge movie

30. Porifera Support • Archaeocytes cells • Can move and change shape • Involved in digestion • Make egg and sperm • Make spicules (small needle-like structures)

31. Porifera Support • Some freshwater sponges can produce gemmules, a seedlike unit that can survive cold temperatures. • Spicules provide support. • Can be sharp (made of calcium carbonate matter) • Can be made out of silica • Can be more flexible (like the fibrous protein spongin)

32. Porifera Motility • Larvae: Free-swimming • Adult Sponge: sessile, usually on the sea floor

33. Porifera Feeding and Digestion • Filter feeder - food particles pass through the pores. - Particles cling to cells - Cells digest food individually.

34. finger or eyed sponge • bright yellow sponge

35. Porifera Reproduction • Sexually • Most sponges are hermaphrodites, have both sexes, which help insure fertilization with sessile animals. • Most sponges are fertilized internally. • Sperm that is carried by water currents. • The larvae can swim for a few days until they attach to a surface. • Asexually • fragmentation • budding

36. 3 Classes/Types of Sponges • Demospongiae • spongin • Calcarea • calcium • Hexactinellida • silica

37. System Type Sponges System Muscular-Skeletal A sponge is a hollow tube with many pores or openings. The skeleton is made of calcium carbonate, silicon or spongin spicules. Digestion A sponge takes in food via the water that flows through the pores. Nervous A sponge has a very low level reaction to the world around it and does not have a brain per se. Circulation A sponge has water flow in through the pores. The water contains the food and oxygen the sponge needs. Respiration A sponge takes in water through its pores, and then canals that move the water all throughout the sponge. Then the oxygen from the water is used. Reproduction A sponge reproduces by budding, fragmentation and also sexually. Excretion A sponge has carbon dioxide and other wastes removed as the water moves in and out through the pores. Symmetry A sponge is asymmetrical or has radial symmetry. Coloration A sponge is white, red, orange, green, yellow, brown, purple, black Sponge Review

38. Cnidarians Jellyfish and Sea Anemones

39. Jellyfish

40. Cnidarian Features • Mostly marine organisms • Radial symmetry • Two cell layers with only one body opening • Tissues made of ectoderm and endoderm • Simple nervous system called the nerve net • Obtain oxygen by diffusion

41. New Scyphozoan Jellyfish Discovered (May 2003) Tiburonia granrojo (Big Red) was taken during a remotely operated vehicle (ROV) dive on the Gumdrop Seamount off the coast of California. Can be up to 1 m in diameter. Lives between 650-1500 m deep.

42. Sea Anemones Coral Polyps

43. Cnidarian Digestion • Cnidocytes • Stinging cells on tentacles that capture prey • Comprised of nematocysts • A capsule • A coiled, threadlike tube • Poison • Barbs, sharp enough to penetrate a crab shell

44. It only takes 3/1000ths of a second for the nematocyst to discharge

45. Cnidarian Reproduction • Asexual is through budding • Sexual reproduction is through fertilization of eggs and sperm • Can be internal or external fertilization

46. Cnidarian Reproduction Two life stages of Cnidaria: • Medusa- floating 2.Polyp- sessile

47. Life Cycle of a Jellyfish

49. Cnidarian Classes/Types Class Hydrozoa • Have both the polyp and medusa stages of life • Can form colonies • Two kinds: 1. Hydroids – hydra 2. Siphonophores – colonies of hydra ex. Portuguese Man of War

50. Colony of Hydra