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Diversity of Life – Animals
PORIFERA – The Sponges
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A Phylogeny of the Eukaryotes
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A Phylogeny of the Animal Phyla
Porifera No true tissues Cnidaria radial symmetry diploblastic Ctenophora Platyhelminthes Acoelomates Rotifera Pseudocoelomates Nematoda Nemertea Mollusca Protostomes true tissues Annellida Arthorpoda Bilateral symmetry triploblastic Bryozoa Lophophorate phyla Body cavity Phoronida Coelomates Brachiopoda Echinodermata Chordata Deuterostomes
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First Step – Evolution of Multicellularity
Three Theories 1. Symbiotic Theory: Two or more unrelated organisms "cooperated" in a symbiotic relationship - became so specialized and dependent on one another that they fused genetically into a single organism. Validity? Unlikely – lots of symbiotic relationships with no genetic fusion 2. Syncytial Theory: Multinucleate protists or slime molds may have evolved cellular membranes between their floating nuclei (organisms with multinucleate cytoplasms are said to be syncytial). Validity? Unlikely – nuclei in syncytial organisms have different functions
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First Step – Evolution of Multicellularity
Three Theories Colonial Theory: Involves symbiosis within a species - such relationships can be seen in extant species (Volvox, etc.). Validity Theory with the most evidence supporting it.
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First Step – Evolution of Multicellularity
Three Theories Colonial Theory – Hypothesized steps 1. Flagellated protists Chlamydamonas Euglena 2. Groups of flagellated cells surrounded by a capsule Volvox 3. Large colonial groups Pandorina Eudorina
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Choanoflagellates
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Choanoflagellates Monosiga
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Hypothesized Origins of Sponges
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Porifera - the sponges Description Sponges are
• sessile (= don’t move) • have no true tissue • suspension feeders
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Porifera - the sponges Come in a wide variety of shapes and sizes
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Sponge structure Atrium Osculum (= spongocoel) Ostia Body wall
General structure Cell types Support Water flow and feeding Reproduction Sponge structure Atrium (= spongocoel) Osculum Ostia Body wall
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Sponge structure - Cell types
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Cell types
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Sponge structure - Cell types
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Cell types Choanocytes - flagellated ‘collar cells’ used in feeding Epidermal cells - the cells forming the outer layer of the animal- the pinacoderm Spicules - rods of silica, or carbonate that are used for support Mesohyl - a gelatinous matrix between two layers of cells Arachaeocytes (amoebocytes) - amoeba-like cells that transport food, make ‘skeletal’elements
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Mesohyl - gelatinous matrix Fibrinonectin Collagen Galectin
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Without support the mesohyl would collapse mesohyl
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Sponges get support from a network of spicules embedded in the mesohyl Same principle as putting straw in mud bricks
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Spicules can be made from different materials Siliceous [Silica (SO2)] Calcareous [Calcium (CaCO3)] Spongin [Protein]
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Spicules can be made from different materials -siliceous and calcareous spicules are secreted by specialized amoebocytes
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Sponge structure - Support
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Support Arrangement of spicules can be haphazard or very precise
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction Sponge structure - Feeding Water flows out through the osculum Water flows in through the ostia
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction General structure Cell types Support Water flow and feeding Sponge structure - Feeding Water flows out through the osculum Water flows in through the ostia
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction Sponge structure - Feeding Water flow is generated by the beating of the flagella in the choanocytes
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction Sponge structure - Feeding Food particles trapped on collar Food particles transferred to ameobocyte Food particles transported down the collar Food particles absorbed by cell
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction Sponge structure - Feeding ostium osculum organics digestion • • • • inorganics Water flow egested >50 m digestion
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Sponge structure - Feeding
General structure Cell types Support Water flow and feeding Reproduction Sponge structure - Feeding digestion • • • Water flow Velocity of water
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Types of Sponges Asconoid Syconoid Leuconoid Increase in efficiency Increase in SA/Vol ratio
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Types of Sponges Asconoid Stagnant area Syconoid Leuconoid
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Sponge Reproduction 1. Asexual a. Fragmentation General structure
Cell types Support Water flow and feeding Reproduction Sponge Reproduction 1. Asexual a. Fragmentation
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Sponge Reproduction 1. Asexual a. Fragmentation b. Budding c. Gemmules
General structure Cell types Support Water flow and feeding Reproduction Sponge Reproduction 1. Asexual a. Fragmentation b. Budding c. Gemmules spicules amoebocytes
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Sponge Reproduction 2. Sexual All sponges are hermaphrodites
General structure Cell types Support Water flow and feeding Reproduction Sponge Reproduction 2. Sexual All sponges are hermaphrodites Development of sperm choanocyte chamber Sink into mesohyl Form spermatic cyst or choanocyte
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Sponge Reproduction 2. Sexual All sponges are hermaphrodites
General structure Cell types Support Water flow and feeding Reproduction Sponge Reproduction 2. Sexual All sponges are hermaphrodites Development of eggs archaeocyte engulfs adjacent cells (yolk) yolk
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Sponge Reproduction 2. Sexual All sponges are hermaphrodites
General structure Cell types Support Water flow and feeding Reproduction Sponge Reproduction 2. Sexual All sponges are hermaphrodites Eggs and sperm form Sperm ejected into water flow And leave through osculum Taken into nearby sponge Delivered to egg by archaeocyte Larva
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Classification of Sponges
Calcarea Porifera Demospongia Hexactinellida
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Numbers of species
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