Class notes (Proifera)

About 8,000 species, mostly marine

Sponge features:

  • No organ system
  • Most are asymmetrical
  • Have highly specialized cells
  • Many sponge cells are totipotent; can differentiate into many different cell types
  • cells can be dissociated, separated, and then they will reaggregate


Proifera diversity

  • Class Calcarea
  • Class Demospongiae
  • Class Hextactinellida


Sponge reproduction

  • Asexual – buds breaking off or fragmentation, gemmules (for freshwater)
  • Sexual – internal fertilization, monoecious (sequential hermaphrodites)
    • Sperm is produced by choanocytes, exits via the oscula, captured by another sponge’s choanocytes, transferred to the mesohyl where eggs are fertilized, embryo develops in the mesohyl, then larvae breaks out into spongocoel, exits through the oscula


Sponges can use physical or chemical defenses

  • Manufacture a broad spectrum of biotoxins (allelochemicals)
  • Use “chemical warfare (allelopathy) to compete for space with other benthic organisms
  • Some have been isolated for their potential pharmaceutical use as antibiotic, anti-tumor, or anti-inflammatory activity

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