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diversity 2 - Mapping body plan characters without a on the tree Key concepts ARTHROPODA

NEMATODA • Simple animals may be ANNELIDA

MOLLUSCA evolutionarily successful, have PLATYHELMINTHES

CNIDARIA RADIAL SYMMETRY diverse life styles and behavior! MOUTH PORIFERA ECHINODERMATA • Basic of CHORDATA Porifera/ / AND Platyhelminthes/ Nematoda TRUE COELOM MOUTH AND ANUS

BILATERAL SYMMETRY TISSUES 1 EXTRACELLULAR DIGESTION 2 PROTISTAMULTICELLULARITY

Today: phyla without a true coelom Diversity of

PROTOSTOMES A. Body plan - ARTHROPODA DEUTEROSTOMES NEMATODA cells in ANNELIDA

MOLLUSCA extracellular PLATYHELMINTHES

CNIDARIA matrix, tube RADIAL SYMMETRY MOUTH PORIFERA ECHINODERMATA structure CHORDATA with flow of AND 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. 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 , 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 (fertilized choanocytes, released egg) gives into the environment rise to swimming Choanocytes of other - 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

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Many cnidarians have both forms in their Diversity of Cnidaria life cycle, in others, one form predominates Feeding Which form predominates in ? In Adaptations for feeding and defense sea anenomes? In ? - nematocysts - organelles that Polyp Medusa function like miniature harpoons

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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 ‘harpoon’ have toxins fatal to humans b Capturing prey Defense against predators Defending territories (video a trigger segment)

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Diversity of Cnidaria: 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

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Diversity of Cnidaria Corals in particular A is millions of coral Where are the autotrophs in the coral reef 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

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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 “-” 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 - budding off ANNELIDA

MOLLUSCA from polyps PLATYHELMINTHES

CNIDARIA RADIAL SYMMETRY - 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 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 lines the body wall but doesn’t surround the gut

Have a one-way digestive system: a mouth and an anus

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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

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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

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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 for control of pests

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Nematoda - roundworms Nematodes that cause river blindness, elephantiasis in humans 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!

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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?

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