1. What do these animals have in common?

8. Phylum Cnidaria “the jellies”

9. What is a cnidarian? invertebrates more than 9000 species jellyfishes, corals, sea anemones, and hydras. worldwide all but a few are marine

10. two distinct body forms during their life cycles Polyp Medusa

11. polyp = sessile form mouth surrounded by tentacles. - sea anemones, corals, and hydras. medusa = free-swimming form - jellyfish

12. The Medusa -an umbrella-shaped, - floating body = a bell, with mouth on underside. Tentacles Body Form

13. The Polyp Attached to substrate, mouth on top surrounded by tentacles mouth Body Form

14. Body form One body form may be more often seen than the other. In hydras, polyp form is most common form of hydras. In jellyfishes, the medusa form is usually observed. http://www.microscope-microscope.org/gallery/Mark-Simmons/pages/hydra2.htm

15. Body form Most cnidarians undergo a change in body form during their life cycles. Polyp Medusa At some point, most Cnidarians exist as both a polyp and a medusa.

16. Body structure radially symmetrical one body opening two cell layers How is this similar to sponges? Mouth Cavity Bud Disc Outer cell layer Jellylike layer Inner cell layer Tentacle

17. Body structure cell layers are organized into tissues with specific functions - true tissues - inner layer mainly assists in digestion -surrounds the GASTROVASCULAR CAVITY Mouth Tentacle Cavity Bud Disc Outer cell layer Jellylike layer Inner cell layer

18. Body structure two cells layers allows easy diffusion of: - Oxygen - dissolved in water, it can diffuse directly into body cells. - Carbon dioxide /other wastes - moves out of the body cells directly into the surrounding water.

19. Reproduction in cnidarians sexual and asexual reproduction Sexual reproduction occurs in only in the Medusa phase if it has both forms in life cycle IF there is NO medusa stage, then the polyp can reproduce sexually.

20. Male Female Eggs Blastula Larva Polyp Asexual Reproduction Bud Sexual Reproduction in Cnidarians Both the medusae and polyps are diploid (2n) animals. Diploid = 2 full sets of chromosomes Per body cell Fertilization

21. Nematocyst before discharge Nematocyst after discharge

22. Digestion in cnidarians Predators - capture or poison prey using nematocysts - a capsule that contains a coiled, threadlike tube. -tube may be sticky or barbed, and may contain toxins - located in stinging cells that are on tentacles

23. Digestion in cnidarians Once captured by nematocysts, prey is brought to the mouth by contraction of the tentacles. Mouth Medusa Mouth Gastrovascular cavity Polyp

24. Food enters gastrovascular cavity digestive cells release enzymes to break down prey undigested materials are ejected back out through the mouth.

25. Diversity of Cnidarians There are four classes of cnidarians: Hydrozoa Anthozoa Scyphozoa Cubozoa

26. Class Hydrozoa 2 groups - hydroids (hydra) - siphonophores (Portuguese man-of-war) marine animals Most hydrazoans go through both stages Hydra - polyp stage only reproduce by budding found attached to piers, shells, and other surfaces. #1 budding developmentSea monkey daphnia

27. The siphonophores - floating colonies -drift about on ocean’s surface. The Portuguese man- of-war, Physalia, is an example of a siphonophore hydrozoan colony Different functions for different individuals Class Hydrozoa

28. Class Anthozoa exhibit only the polyp form. Corals Sea anemones Sea fans Sea apple feeding

30. live in colonies of polyps in warm ocean waters around the world. secrete protective, cuplike calcium carbonate shelters around their soft bodies. Colonies of many coral species build the coral reefs provide food and shelter for many other marine species. Corals

31. Corals that form reefs are = hard corals. soft corals= do not build calcium carbonate structures – not reef builders. Corals

32. Living portion of a coral reef is a thin, fragile layer grows on top of the shelters left behind by previous generations. Often found in shallow, nutrient-poor waters, thrive because of symbiotic relationship with microscopic, photosynthetic protists called zooxanthellae. Corals

35. Bleaching Worldwide

36. Zooxanthellae produce oxygen and food that corals use, Uses carbon dioxide and waste materials produced by the corals cause bright colors found in coral reefs. free-swimming, sometimes leave the corals Caused by warming ocean temperatures and Increasing acidity due to increased CO2 in atmosphere Corals die without them = “bleaching” 70% bleached in 20-30 yrs; 35 million acres so far

38. Coral reefs provide habitat for 25% of marine fish About 1 billion people rely on fish as their primary food source Tourism – over a billion dollars is spent every year in the Caribbean, Australia (3.9 billion/year), and the Pacific Islands 1.2 Billion in Florida each year Most diverse ecosystem – “Ocean Rainforest” 4000 species of fish, 800 species of coral

39. Corals are used for pharmaceuticals Chemical extracts from corals have helped create drugs to treat AIDS, Cancer, Arthritis, Inflammatory disorders, and pain killers Beneficial for patients with heart, kidney, and liver transplants.

40. Class Scyphozoa = jellyfish Fragile sometimes luminescent bodies Some are transparent May be pink, blue, or orange. Medusa form is the dominant stage in this class.

41. Class Scyphozoa muscle-like cells in outer cell layer can contract When these cells contract, the bell contracts propels the animal through the water.

42. Class Cubozoa Box jellyfish Originally included in Class Scyphozoa. Differences: –Their bells are square-shaped, instead of round –They have primitive brians –They have eyes –They swim, not float –They sleep

43. Class Cubozoa The Irukandji in Australia is one of the most dangerous animals It is very small, only 2.5 cm from bell to tentacles

45. Giant Jellyfish Japan has been invaded by Nomura’s jellyfish – the giant jellyfish.

46. Research: What are Nomura’s Jellyfish? Where are they found? Just Japan? What causes them to get so big? Are they dangerous? Are they new? Or are they only now getting noticed?

47. Giant Jellyfish 6.5 ft wide and 450 lbs More common in China and Korea Only recently in Japan

48. Giant Jellyfish Not much is known, Japan studying mating/migration habits Choking fishing nets Possible warmer seas (global warming) causes increase in population http://video.google.com/videoplay?docid=2208948115892996006&q=giant+jellyfish&t otal=103&start=0&num=10&so=0&type=search&plindex=0

49. The earliest known cnidarians also date to the Precambrian, about 630 million years ago. The earliest coral species were not reef builders, so reefs cannot be used to date early cnidarians. The larval form of cnidarians resembles protists, and because of this, scientists consider cnidarians to have evolved from protists. Where did they come from?