Lecture 5 – Porifera & Placozoa Student Version PDF

Lecture 5 – Porifera & Placozoa Sponges Placozoans and other mesozoan phyla Phil Dustan photo Metazoans but NOT Bilaterians  Phylum Porifera: Sponges Literally, “pore-bearing” Parazoan – lack true embryological germ layers True tissues absent; multicellular but cells to...

Lecture 5 – Porifera & Placozoa Sponges Placozoans and other mesozoan phyla Phil Dustan photo Metazoans but NOT Bilaterians  Phylum Porifera: Sponges Literally, “pore-bearing” Parazoan – lack true embryological germ layers True tissues absent; multicellular but cells totipotent Sessile, suspension feeders with unique system of water canals http://waterquality.ec.gc.ca/WaterQualityWeb/media/cabin/bugs/Porifera.jpg  http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/spongeREAGG.jpg Re-aggregation  Additional Characteristics of Sponges Asymmetrical or +/- radially symmetrical Unique water-collar cells: choanocytes ecographica.blogspot.com/2009_04_01_archive.html  Sponge Skeleton & Taxonomy Spicules – Calcium carbonate → Class Calcarea – Siliceous & 6-rayed → Class Hexactinellida – If siliceous, not 6-rayed; or made of collagen (“spongin”) → Class Demospongiae oceanlink.island.net/LEYS/images/SPICULES.gif *Image courtesy Indigo® Instruments.  Class Calcarea Spicules of calcium carbonate laid down as calcite All marine Leucosolenia eleanor http://coris.noaa.gov/glossary/calcarea_186.jpg  Class Hexactinellida 6-rayed, siliceous spicules All marine, mainly deep water Glass sponges oceanexplorer.noaa.gov/.../glass_sponge.html http://www.palaeos.com/Invertebrates/Porifera/Images/Allonia.jpg  Structural design of Venus’ flower basket Design mirrored in civil and mechanical engineering Swiss Tower (London) Hotel De Las Artes (Barcelona) Eiffel Tower scienceforward.blogspot.com/2008_04_01_archiv...  Glass sponges: First light transducers Light transduced along glass spicules Allows light into otherwise dark cavities – Permits photosynthetic symbionts to survive Tethya aurantium (Credit: Univ. of Stuttgart / Zoology)  Class Demospongiae Siliceous spicules but not 6-rayed Spicules may be replaced with collagenous network (“spongin”) Marine, brackish & freshwater, all depths Images of representative demosponges en.wikipedia.org/wiki/Demosponge © James Watanabe Cliona californiana  Ogulin Cave Sponge Only known subterranean freshwater sponge Croatia http://www.ruffordsmallgrants.org/rsg/projects/jana_bedek_0  Sponge Bauplan http://johnson.emcs.net/life/_derived/invert.htm_txt_sponge.gif  Show & Tell In which Class do these sponges belong?  Car Wash Sponge https://shop.advanceautoparts.com/p/autocraft-giant-bone-car-wash-sponge-ac247/6140025- p?product_channel=local&store=9458&adtype=pla_with_promotion&product_channel=local&store_code=9458&&&&&gad_source=1&gclid=CjwKCAjwxNW2BhAkEiwA24Cm9B9iVJ0hmOb0JPzlefSZ LuQEwWdEo-l8irYvim4dmmJxJcGXUmkIlxoCLAgQAvD_BwE&gclsrc=aw.ds  Luffa https://images.app.goo.gl/1N1tkZ2CHf8vikJZ9  Water Transport Networks and Sponge Size Asconoid – Simple, continuous choanoderm, one cell thick – Small (< 10 cm), vase shaped Syconoid – Choanoderm folded – Typical of many calcareous sponges Leuconoid – Choanoderm subdivided into distinct individual chambers – Typical of most calcareous sponges and all demosponges  Asconoid Sponge Leucosolenia File:Porifera body structures 01.png rydberg.biology.colostate.edu/Dissections/CPl... http://www.marlin.ac.uk/imgs/o_leubot.jpg commons.wikimedia.org/wiki/File:Porifera_body... commons.wikimedia.org/wiki/File:Porifera_body...  Syconoid Sponge Scypha File:Porifera body structures 01.png www.horta.uac.pt/.../Scypha_ciliata.html commons.wikimedia.org/wiki/File:Porifera_body... commons.wikimedia.org/wiki/File:Porifera_body...  Leuconoid Sponge www1.fccj.cc.fl.us/dbyres/images/comm40.jpg Leuconia Schematic of cross-section through a leuconoid sponge, showing extensive pocketing lined with choanocytes, plus incurrent and radial canals. SC0001s commons.wikimedia.org/wiki/File:Porifera_body... www.habitas.org.uk/.../porifera/SC0001s.jpg  Feeding Sponges are filter feeders Water enters through ostia – Controlled by surrounding porocyte cells Water movement partially passive – Result of sponge architecture Beating of flagellated choanocyte cells also move water pigeonchess.com/.../  Clearance rates Sponges filter massive amounts of water Clearance rate of Spongia officinalis var. adriatica = 210 ml h−1 g−1 DW (Stabili et al. 2006: doi:10.1016/j.watres.2006.06.012 ) Caribbean sponges filter the equivalent of their entire sea in one day! Video: https://www.youtube.com/watch?v=pTZ211cIjX8&v l=en  Nutrition Food particles trapped on outside of choanocytes and phagocytized – Food particles not digested by choanocytes – Passed to amebocytes in the mesohyl, which migrate to cells requiring food http://cas.bellarmine.edu/tietjen/images/sponges.htm  Excretion & Gas Exchange How do sponges respire and excrete? http://www.emc.maricopa.edu/faculty/farabee/BIOBK/sponge_2.gif  Asexual Reproduction Sponges reproduce asexually by fragmentation, budding or production of gemmules Gemmules typical of freshwater sponges; essentially “survival pods” Corvoheteromeyenia heterosclera with recently formed gemmules www.flmnh.ufl.edu/ucamara/specieslists.htm  Sexual Reproduction Most species monoecious – Sperm produced by choanocytes – Eggs formed by archeocytes Mass spawning Video of barrel sponges spawning in the FL Keys: https://www.youtube.com/watch?v=5zWrSmpkV_I  Sponge Larvae Two types of larvae – Parenchymella larvae = solid – Amphiblastula larvae = hollow Both types ciliated www.palaeos.com/.../Porifera/Demospongiae.3.html www.palaeos.com/.../Porifera/Demospongiae.3.html  Ecological Success of Sponges Common in unpolluted freshwaters and very abundant in marine environment Sessile, often large & brightly colored – why are sponges not eaten?  Ecological Importance of Sponges Water-filtering Symbiotic with small shrimps & fishes Used as camouflage by decorator crabs Bioerosion – boring sponges – Use specialized cells (etching cells) that chemically and mechanically chip calcareous materials http://www.prionace.it/Cliona%20orientalis.jpg www.pznow.co.uk/.../marine/spongeholes.jpg  Economic Importance of Sponges Bath sponges – harvested commercially in Mediterranean & Tarpon Springs, FL Palomares, D., Derrick, B., Chu, E., & Pauly, D. (2020). The global catch of commercial sponges (1950 to 2019). Fisheries Centre Research Reports, 30, 85.  Phylum Placozoa Mesozoans – A grade of organization – Multicellular but lack many other metazoan characteristics – Recent phylogenetic analyses suggest that Placozoa is a sister group to Cnidaria, or to the clade of Cnidaria + the Bilateria  Phylum Placozoa Greek Plakos = flat, zoon = animal 2-3 mm diameter, two cell layers with mesochymal ameboid cells sandwiched between them Ciliated Ventral surface invaginates for feeding Trichoplax adherens Video: Stanford researchers decode an ancient, Smallest genome extraordinary animal https://www.youtube.com/watch?v=pnKXuVV5C18 of all animals  Placozoan bauplan & reproduction Srivastava, M., Begovic, E., Chapman, J. et al. The Trichoplax genome and the nature of placozoans. Nature 454, 955–960 (2008). https://doi.org/10.1038/nature07191