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Chapter 5:                       Porifera & PlacozoaBIOL 201:                               Rob Swatski                   ...
PhylumPoriferaPorifera = the “pore- bearing” spongesNot considered to be   eumetazoansPosses epithelioid &   rudimentary c...
PoriferaOverview  8000 species, most   marine, 150 FW Primitive, sessile filter         feeders  Most asymmetrical,   but ...
Sponge Body PlansAsconoid   Syconoid   Leuconoid                                  4
AsconoidSponges Simplest body plan:  hollow tube with   base attached to      substrate   Ex: Leucosolenia     Have 1 larg...
AsconoidSponges,  cont. Water exits spongocoel  through single large        osculumSmallest & thinnest of all    sponges (...
SyconoidSponges Body wall has incurrent   canals & outpockets     (radial canals or choanocyte chambers) lined with choano...
Syconoid sponge(Sycon)                  8
Leuconoid Sponges    Contains 1000’s of  choanocyte chambers,    further increasing     choanoderm SA Smaller excurrent ca...
10   Leuconoid sponge
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Structure ofSponge Body    Wall   Classified as either  cellular or syncytial   Cellular sponges   have 2 primitive   prim...
Epithelioid Tissue     Pinacoderm                 Choanoderm   Covers outer body & lines                                Fl...
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Mesohyl Tissue       (all cells are dynamic, totipotent & amoeboid)   Archeocytes              Lophocytes          Spongoc...
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Mesohyl Tissue, cont.   Sclerocytes              Myocytes              Germ cells                           Muscle-like ce...
FW Leuconoidsponge               18
Syncytial Sponges Contain simpler,    No pinacoderm &     Collar bodies are    Mesohyl withreduced cells in a   choanoderm...
SyncytialSponges,  cont.     Body wall  resembles 3-D   cobweb-likepattern: trabecular    syncytium Each strand of the    ...
Porifera TaxonomySP Symplasma             Subphylum Cellularia(Hexactinellida)             (Cellular Sponges)             ...
Glass Sponge(SP Symplasma)                 22
SP Cellularia23   (Class Demospongiae)
SP Cellularia(Class Calcarea)                   24
SP Cellularia(Class Calcarea)                   25
SpongeSkeletonDiverse mesohyl actsas an endoskeletonSome skeletons have fine collagen fibers         onlyMay contain spicu...
27
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WaterPumping Most pump a watervolume equal to theirbody volume every 5      seconds   Large SA & flowregulation slows down...
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Locomotion  Some have limited  ability to move (1-4      mm per day)   Result of collective  amoeboid movement  of cells: ...
Nutrition Filter feeders able to  phagocytize food <50µm (dinoflagellates,   bacteria, viruses,         debris)Some are ca...
35
SymbioticRelationships     Some have PSN     endosymbionts:      cyanobacteria,     dinoflagellates,       chlorophytes  S...
InternalTransportGas & waste transport via simple diffusionSponges are “leaky,” sowater penetrates their     entire bodySh...
InternalTransport,   cont. Ammonia is the main   metabolic waste Common nitrogenous   waste in aquatic    environments Arc...
Nervous Tissue  Lack nerve cellsSome have localized action potentials  responsible formyocyte contraction   Glass sponges ...
SpongeEcology Many producetoxins to prevent    predation    Food for  spongivores:nudibranchs, fish,     turtles Hawksbill...
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SpongeEcology, cont.Habitat for animals(shrimps & brittle      stars)  Decorator crabs place sponges ontheir carapaces for...
44
Reproduction  Clonal reproduction  via fragmentation &         budding    Sponges display  incredible powers of      regen...
Reproduction,    cont.   Sponges frequently   reproduce sexually    Hermaphrodites     (monoecious)    Germ cells occur  t...
Reproduction,    cont.  Sperm are broadcasted    into water column       Choanocytes   phagocytize incoming  sperm, but do...
Reproduction,    cont.   Some sponges are   oviparous: release   zygotes into water        column  Most are viviparous:  r...
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Reproduction,    cont.  Larvae are short-lived,  settle in a few days, &  creep across substrate   until suitable spot is ...
PhylumPlacozoaTrichoplax: superficiallyresembles large ameba   (2-3 mm diameter)  Upper & lower cell  layers, 25 µm thickE...
PhylumPlacozoa, cont.     Fiber syncytium: CT   layer of watery ECM &      syncytial network;         contractile    Resem...
PlacozoanPhylogeny Early evolutionary line  of simple metazoans Intermediate between  sponges & cnidarians  (RNA sequence ...
Credits                    by Rob Swatski, 2010      Visit my website for more Biology study resources!                   ...
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BIOL 201 Chp 5 Porifera and Placozoa

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This is a lecture presentation for my BIOL 201 Invertebrate Zoology students on Chapter 5: Porifera and Placozoa (Invertebrate Zoology, 7th Ed. by Ruppert, Fox, & Barnes, 2004).

Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College - York Campus, York, PA.
Email: rjswatsk@hacc.edu

Please visit my website, BioGeekiWiki, for more biology learning resources: http://robswatskibiology.wetpaint.com

Visit my Flickr photostream for anatomy model photographs!
http://www.flickr.com/photos/rswatski/

Thanks for looking!

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Transcript of "BIOL 201 Chp 5 Porifera and Placozoa"

  1. 1. Chapter 5: Porifera & PlacozoaBIOL 201: Rob Swatski Asst. Prof. BiologyInvertebrate Zoology HACC-York 1
  2. 2. PhylumPoriferaPorifera = the “pore- bearing” spongesNot considered to be eumetazoansPosses epithelioid & rudimentary connective tissue Lack true muscle & nervous tissues 2
  3. 3. PoriferaOverview 8000 species, most marine, 150 FW Primitive, sessile filter feeders Most asymmetrical, but some display radial symmetry Erect, branching, or encrusting on substratum 3
  4. 4. Sponge Body PlansAsconoid Syconoid Leuconoid 4
  5. 5. AsconoidSponges Simplest body plan: hollow tube with base attached to substrate Ex: Leucosolenia Have 1 large spongocoel (atrium) lined with 1 layer of choanoderm Choanocytes beat & draw water through ostia (aquiferous system) 5
  6. 6. AsconoidSponges, cont. Water exits spongocoel through single large osculumSmallest & thinnest of all sponges (1 mm diameter) Growth imited by spongocoel diameter If they had larger diameters, their body volume would exceed pumping capacity of choanoderm 6
  7. 7. SyconoidSponges Body wall has incurrent canals & outpockets (radial canals or choanocyte chambers) lined with choanodermIncreases choanoderm SA & decreases spongocoel volume Larger than asconoidsponges (several cm), with thicker body wallsGrantia & Sycon (Scypha) 7
  8. 8. Syconoid sponge(Sycon) 8
  9. 9. Leuconoid Sponges Contains 1000’s of choanocyte chambers, further increasing choanoderm SA Smaller excurrent canals further reduce spongocoel diameter The largest sponges (several cm – 1+ m), with the thickest body walls; indeterminate growth May have more than one osculum 9
  10. 10. 10 Leuconoid sponge
  11. 11. 11
  12. 12. Structure ofSponge Body Wall Classified as either cellular or syncytial Cellular sponges have 2 primitive primary tissues: epithelioid & mesohyl Epithelioid tissue resembles epithelium Mesohyl: middle CT layer of fibrous ECM 12
  13. 13. Epithelioid Tissue Pinacoderm Choanoderm Covers outer body & lines Flagellated cells with a inner chambers (around collar of microvilli choanoderm)Pinacoytes Porocytes Choanocytes 13
  14. 14. 14
  15. 15. Mesohyl Tissue (all cells are dynamic, totipotent & amoeboid) Archeocytes Lophocytes Spongocytes Can differentiate into Produce thick Secrete & maintainany sponge cell; aide in skeletal spongin collagen fibersdigestion (phagocytosis) fibers & internal transport 15
  16. 16. 16
  17. 17. Mesohyl Tissue, cont. Sclerocytes Myocytes Germ cells Muscle-like cells Reproductive Secrete spicules: around osculum that cells: oocytes &skeletal elements made constrict or dilate to spermatocytes of silica or calcium control water flow 17
  18. 18. FW Leuconoidsponge 18
  19. 19. Syncytial Sponges Contain simpler, No pinacoderm & Collar bodies are Mesohyl withreduced cells in a choanoderm; have located archeocytes, syncytium, a collar bodies individually in sclerocytes, & continuous instead collar body germ cells cytoplasm that chambers (not inlacks membranes epithelioid sheets) 19
  20. 20. SyncytialSponges, cont. Body wall resembles 3-D cobweb-likepattern: trabecular syncytium Each strand of the trabecularsyncytium encloses an axis of mesohylContains collagen & spicules 20
  21. 21. Porifera TaxonomySP Symplasma Subphylum Cellularia(Hexactinellida) (Cellular Sponges) Class Class Glass Demospongiae: sponges: Calcarea: 80% of all sponges; calcareous syncytial siliceous spicules & spicules spongin 21
  22. 22. Glass Sponge(SP Symplasma) 22
  23. 23. SP Cellularia23 (Class Demospongiae)
  24. 24. SP Cellularia(Class Calcarea) 24
  25. 25. SP Cellularia(Class Calcarea) 25
  26. 26. SpongeSkeletonDiverse mesohyl actsas an endoskeletonSome skeletons have fine collagen fibers onlyMay contain spicules, spongin, or bothIncredible diversity ofspicules: some project through mesohyl to protect outer sponge body 26
  27. 27. 27
  28. 28. 28
  29. 29. 29
  30. 30. WaterPumping Most pump a watervolume equal to theirbody volume every 5 seconds Large SA & flowregulation slows down velocity Contract or relax myocytes to adjust osculum diameterCan also close ostia &adjust flagellar beat of choanoderm & collar bodies 30
  31. 31. 31
  32. 32. 32
  33. 33. Locomotion Some have limited ability to move (1-4 mm per day) Result of collective amoeboid movement of cells: very dynamic mesohyl environment (remodeling) Osculum contraction by myocytes Whole body contraction 33
  34. 34. Nutrition Filter feeders able to phagocytize food <50µm (dinoflagellates, bacteria, viruses, debris)Some are carnivores &don’t filter; trap small animals such as crustaceans Choanocytes transfer particles to vacuoles for digestion Archeocytes remove wastes & inorganics from system 34
  35. 35. 35
  36. 36. SymbioticRelationships Some have PSN endosymbionts: cyanobacteria, dinoflagellates, chlorophytes Symbionts help create the bright colors of sponges Sponges must live in shallow water for PSN Some obtain up to 80% of nutrients from photosynthate 36
  37. 37. InternalTransportGas & waste transport via simple diffusionSponges are “leaky,” sowater penetrates their entire bodySheets of cells are only 1 cell layer thickMobile amoeboid cells 37
  38. 38. InternalTransport, cont. Ammonia is the main metabolic waste Common nitrogenous waste in aquatic environments Archeocytes transfer wastes & nutrients Some individual cells posses contractile vacuoles 38
  39. 39. Nervous Tissue Lack nerve cellsSome have localized action potentials responsible formyocyte contraction Glass sponges generate AP’s thattravel rapidly across their syncytium Used to stop flagellar beating 39
  40. 40. SpongeEcology Many producetoxins to prevent predation Food for spongivores:nudibranchs, fish, turtles Hawksbill turtlefeces can be up to 95% siliceous spicules! Some releasechemicals that kill sessile competitors (corals ) 40
  41. 41. 41
  42. 42. 42
  43. 43. SpongeEcology, cont.Habitat for animals(shrimps & brittle stars) Decorator crabs place sponges ontheir carapaces for defense & glidingCliona breaks down calcareous shellsBores into shells for protection 43
  44. 44. 44
  45. 45. Reproduction Clonal reproduction via fragmentation & budding Sponges display incredible powers of regeneration Reproduce as a response to wave damage or grazing Gemmules: spore-like masses of nutrient- rich archeocytes enclosed by a shell; undergo diapause 45
  46. 46. Reproduction, cont. Sponges frequently reproduce sexually Hermaphrodites (monoecious) Germ cells occur throughout mesohyl Choanocytes can also release sperm & form eggs 46
  47. 47. Reproduction, cont. Sperm are broadcasted into water column Choanocytes phagocytize incoming sperm, but don’t digest them Choanocytes differentiate into an amoeboid cell & deliver sperm head to egg Most eggs fertilized via phagocytosis (most sponge sperm lack an acrosome) 47
  48. 48. Reproduction, cont. Some sponges are oviparous: release zygotes into water column Most are viviparous: retain zygotes within body Release larvae at a later period Sponge larvae are very diverse: coeloblastula, amphiblastula, parenchymella 48
  49. 49. 49
  50. 50. Reproduction, cont. Larvae are short-lived, settle in a few days, & creep across substrate until suitable spot is found Metamorphose into a juvenile Varied lifespan: live several years in temperate waters; 200+ years in tropics or deep sea Some only grow 0.2 mm/yr & could be 5000 years old with constant growth rate 50
  51. 51. PhylumPlacozoaTrichoplax: superficiallyresembles large ameba (2-3 mm diameter) Upper & lower cell layers, 25 µm thickEnclosed by single layer of epithelioid cellsDensely ciliated ventralsurface for locomotion 51
  52. 52. PhylumPlacozoa, cont. Fiber syncytium: CT layer of watery ECM & syncytial network; contractile Resembles ameba in form & locomotion as it glides across substratum Feeds on algae via extracellular digestion Reproduces asexually via budding & fragmentation; sexual repro & larvae unknown 52
  53. 53. PlacozoanPhylogeny Early evolutionary line of simple metazoans Intermediate between sponges & cnidarians (RNA sequence data)Resembles hypothetical protometazoanEpithelioid layer is moresimilar to true epithelial tissue 53
  54. 54. Credits by Rob Swatski, 2010 Visit my website for more Biology study resources! http://robswatskibiology.wetpaint.com http://www.flickr.com/photos/rswatskiPlease send your comments and feedback to: rjswatsk@hacc.edu This work bears an Attribution-Noncommercial Share Alike Creative Commons license. 54
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