KG

Phylum Porifera

  • Reminder:

    Protist = unicellular eukaryotes, no undergo gastrulation or tissue development

    Metazoans = multicellular eukaryotes undergo gastrulation and tissue development

  • Basal Metazoan - early development

Porifera

  • sponges

  • benthic organisms ( bottom sea floor)

  • Not protist but also not metazoans

    • multicellular organism that has specialized cells for life functions

    • posses some metazoan characteristics

  • Characteristics

    • multicellular from embryonic layering

    • cell-cell communication

    • animal-like reproduction, with larval stage

    • Aquiferous system: water current channel powered by flagellated cells called choanocytes

      • nutrition: brings water containing food through the sponge where cells can phagocytize food particles

      • respiration: water contains oxygen where individual cells can carry out gas exchange

      • waste management: metabolic and digestive waste carried out through water currents

    • on cellular level: specialized cells carry out life function

  • Cellular Organization:

    • Cell types

      • organized into specific areas but are not true tissues

      • All cells = totipotent ( important for making up cell with aquifer)

      • pinacocyte: forms outer layer of sponge

      • amoebocyte: digestive and transports nutrients through body

      • porocyte: single cell, creates pores for water flow

      • choanocyte: all-purpose cells; water flow in, feeding, gas exchange, and waster

  • Body Type

    • Asconoid sponge

      • simplest

      • water flow through ostia

      • large cavity = spongocoel

      • water flows out through osculum

      • choanocytes line spongocoel

    • Syconoid sponge

      • bit more complex

      • water flow through ostia

      • channels line choanocytes

      • large cavity = spongocoel

      • water flows out through osculum

    • Leuconoid sponge

      • most complex

      • water flows through dermal pore ( ostia)

      • multiple canals and chambers

      • water flows out through osculum

      • choanocytes line chambers

    • Hexactinellid sponge

      • greater degree of radial symmetry

      • no pinacoderm

      • cellular distribution is sparse and forms trabecular network

Spicules

  • help give sponge form, shape, and support

  • type of spicules = taxonomy of sponge

  • Spicules Type:

    • silicious

    • calcareous

    • spongin

Feeding & Nutrient

  • filter feeders ( use choanocytes to create currents)

  • digestion carried out by individual cells

  • phagocytosis

  • pinocytosis

Sensory Capabilities

  • no evidence of use of neurons or discrete sense organs

  • still rely on individual cell responses

Reproduction and Development

  • sexual ( mostly)

  • cells release gametes ( sperm or eggs) into environment

  • Zygote = free-swimming larvae (they land somewhere and take root)

  • some budding ( asexual, clone off themselves and spread off, must contain archaeocytes)

  • Archaeocytes: totipotent cells capable of becoming anything

  • Gemmules: packets of archaeocytes protected by skeleton

Taxonomy

  • Class Calcarea

    • spicules of calcium carbonate

    • the 3 body types

    • all marine

  • Class Demospongia

    • spicules of silicon or sponging

    • Leuconoid

    • marine, brackish, and freshwater

  • Hexactinellida

    • spicules of silicon, 3 or 6-ray

    • trabecular network

    • glass sponge

    • all marine