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Andivers2'06h.O.Pdf Animal diversity 2 - Animals Mapping body plan characters without a coelom on the tree Key concepts PROTOSTOMES ARTHROPODA DEUTEROSTOMES NEMATODA • Simple animals may be ANNELIDA MOLLUSCA evolutionarily successful, have PLATYHELMINTHES CNIDARIA RADIAL SYMMETRY diverse life styles and behavior! MOUTH PORIFERA ECHINODERMATA • Basic biology of CHORDATA Porifera/ Cnidaria/ AND Platyhelminthes/ Nematoda ANUS TRUE COELOM MOUTH AND ANUS BILATERAL SYMMETRY TISSUES 1 EXTRACELLULAR DIGESTION 2 PROTISTAMULTICELLULARITY Today: phyla without a true coelom Diversity of Sponges PROTOSTOMES A. Body plan - ARTHROPODA DEUTEROSTOMES NEMATODA cells in ANNELIDA MOLLUSCA extracellular PLATYHELMINTHES CNIDARIA matrix, tube RADIAL SYMMETRY MOUTH PORIFERA ECHINODERMATA structure CHORDATA AND with flow of water ANUS TRUE COELOM bringing MOUTH AND ANUS food to cells BILATERAL SYMMETRY TISSUES EXTRACELLULAR DIGESTION 3 PROTISTAMULTICELLULARITY 4 B. Feeding If choanocytes specialized for Diversity of Sponges feeding, how are other cell types nourished? C. Reproduction via another cell type Asexual - branches may ‘pinch’ off and - amoeboid cells regenerate that move Sexual - most are hermaphrodites throughout the Hermaphrodite - single individual produces sponge, collecting both male and female gametes and further digesting material from choanocytes, then passing it on to other cells... 5 6 Page ‹#› Diversity of Sponges Diversity of Sponges Sperm are produced from modified The zygote (fertilized choanocytes, released egg) gives into the environment rise to swimming Choanocytes of other larva - sponges ‘capture with choanocytes on sperm’ in intracellular outside for capsules, then movement transform into migrating amoeboid cells, carry sperm to an A ‘smoking sponge’ egg! releasing sperm 7 8 Diversity of Sponges Diversity of Cnidaria C. Reproduction Two basic body forms Larva eventually settles, gives rise to The polyp and the medusa - a mature sponge sedentary and mobile form Polyp Medusa 9 10 Many cnidarians have both forms in their Diversity of Cnidaria life cycle, in others, one form predominates Feeding Which form predominates in jellyfish? In Adaptations for feeding and defense sea anenomes? In coral? - nematocysts - organelles that Polyp Medusa function like miniature harpoons 11 12 Page ‹#› Nematocysts Trigger senses ‘foreign’ chemical profile Diversity of Cnidaria ‘Harpoon’ released - can pierce a crab shell What do cnidarians use their nematocysts for? Releases toxin - some species ‘harpoon’ have toxins fatal to humans b Capturing prey Defense against predators Defending territories (video a trigger segment) 13 14 Diversity of Cnidaria:Corals in Corals in particular… particular… Corals - polyp-form cnidarians, live in Corals - polyp-form cnidarians, live in large large colonies, and secrete calcium colonies, and secrete calcium carbonate carbonate When old polyps die, new ones build on top 15 16 Diversity of Cnidaria Corals in particular A coral reef is millions of coral Where are the autotrophs in the coral reef skeletons with living ones on the community? Corals live in shallow, clear, periphery nutrient-poor water... Corals get much of their energy from photosynthesizing plant-like protists - “zooxanthellae” that live within their cells Coral polyps with zooxanthellae 17 18 Page ‹#› Corals in particular Diversity of Cnidaria Zooxanthellae are dinoflagellates that have Environmental threats developed a mutualism with corals to the coral - Mutualism; interaction between species in zooxanthelle which both partners benefit interaction Ocean pollution - light can’t penetrate cloudy waters “Coral bleaching-” corals lose their zooxanthellae - a recent serious problem 19 20 Coral bleaching: The “adaptive Coral bleaching: What causes it? bleaching hypothesis” Various factors, pollution, UV Bleaching can be adaptive if irradiation, and most importantly, corals give up heat zooxanthellae adapted to Because of global warming, some old environment and pick up new ones, with for predictions that coral reef example, increased heat communities may be extinct within tolerance 50 years Some evidence for this but But there’s some still controversial hope the corals And it’s a high risk strategy - are ahead of us in corals have a limited solving this problem amount of time to reaquire Dead coral being zooxanthellae before colonized by algae 21 they’re dead 22 Flatworms (Platyhelminthes) and Diversity of Cnidaria Roundworms (Nematoda) Reproduction PROTOSTOMES ARTHROPODA DEUTEROSTOMES NEMATODA Asexual reproduction - budding off ANNELIDA MOLLUSCA from polyps PLATYHELMINTHES CNIDARIA RADIAL SYMMETRY Sexual reproduction - fertilized eggs MOUTH PORIFERA ECHINODERMATA give rise to mobile, planktonic CHORDATA forms AND ANUS Plankton - small ocean organisms TRUE COELOM that drift with water movement MOUTH AND ANUS BILATERAL SYMMETRY TISSUES 23 EXTRACELLULAR DIGESTION 24 PROTISTAMULTICELLULARITY Page ‹#› Platyhelminthes Platyhelminthes Body plan Feeding No body cavity Some free-living, many parasites In most mouth but no anus i. Some of the parasites with complex life Lack circulatory, respiratory cycles: several different forms and more system, absorb O2 through than one host body wall Movement? Human liver fluke slowly, through muscle must pass contraction through two other and/or beat cilia in slime trail! hosts to complete life cycle 25 26 Platyhelminthes The platyhelminth parasite Schistosoma Example of a human platyhelminthes parasite: Schistosoma Humans (where parasite reproduces) the definitive host 1) Parasite 1) Parasite eggs shed Snails the intermediate host eggs shed in human in human waste, waste, gets into gets into water water 4) Burrow 4) Burrow into human into human skin, infect 2) Eggs hatch, infect snails skin, infect 2) Eggs hatch, infect snails organs, organs, 3) Snails shed 3) Snails shed reproduce 27 reproduce 28 swimming stage swimming stage The platyhelminth parasite, Platyhelminthes Schistosoma Body plan - causes schistosomiasis Feeding - found throughout tropical Asia, sub- Saharan Africa, mid-East and Latin Reproduction America - some asexual - e.g. can cut - 200 million people infected, chronic Planaria in two infection damages the liver, intestines, - sexual, most hermaphrodites - lungs, 20 million develop ‘severe two hermaphrodites lie next to each other, consequences’ each donates sperm to the other’s egg sac - What changes could help reduce disease transmission? 29 30 Page ‹#› Nematoda - roundworms Nematoda - roundworms Body plan - very simple - “a tube within a tube” Body plan Have a pseudocoelom for body cavity Mesoderm lines the body wall but doesn’t surround the gut Have a one-way digestive system: a mouth and an anus 31 32 Nematoda - roundworms Nematoda - roundworms 20K species, range in length Feeding from 0.3 mm to 8 m (in whale placenta *) Many free living decomposers and * What was it doing there? parasites of almost everything - plants and animals 33 34 On cooking pork... Nematoda - roundworms Trichinella, a roundworm parasite of mammals, including rodents, pigs and Feeding humans Many free living decomposers Pigs get infected from eating uncooked meat scraps or from rodent and contamination, humans from eating parasites of everything - plants undercooked pork and animals Example - Trichinella 35 36 Page ‹#› On cooking pork... On cooking pork... Trichinosis not very common any more •Trichinella worms lay eggs in intestine, young larvae travel through arteries and In 1940, 16% of US human population infected encyst in muscles - can live for years In 1970, 4% • Short-term symptoms - abominal pain, In 1991-1996, average of 38 cases per year vomiting, fatigue and fever Why the improvement? • Then, headaches, fever, aching joints and muscles No raw meat fed to hogs, rodent control, stringent inspections, and freezing and • Later most symptoms subside - chronic thorough cooking of pork more common infection Still a concern with wild game, esp. bear meat 38 37 What about Wilbur? Nematoda - roundworms When parasites are our allies - the use of insect-parasitic nematodes for control of pests 39 40 Nematoda - roundworms Nematodes that cause river blindness, elephantiasis in humans Nematode parasites sometimes have also have mutualist bacteria mutualistic bacterial associates Just recently led to new therapies Insect-parasitic nematodes release bacteria in the host, the bacteria kill with antibiotics the host Some of these bacteria are luminescent! 41 42 Page ‹#› Nematoda - roundworms Nematoda - roundworms Reproduction Reproduction Sexual - some species have The record for reproductive output? both sexes, some are Ascaris the parasitic roundworm, hermaphrodites produces 100,000 - 200,000 eggs per day! Assuming population isn’t growing, what does this say about mortality of immature stages? 43 44 Page ‹#›.
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