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