Sponges - Biology

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  • Believed to be amongst earliest multicellular animals on eart. Oldests fossil = 600 million years old.
  • found in seas all over the world, few species live in fresh water. 
  • Sponges are animals as they have cells with no cell walls.
  • Some have flagella, beating rhythmically, creating a water current that flows through sponge's body where they can extract food material.
  • Flagella cells also have microvilli - increase surface area, therefore making food absorption more efficient. 
  • Other cells are tubula, providing pores where the water current can circulate. Others secrete collagen, others secrete little spicules of calcium carbonate (silica) which provide a skeleton for the sponge.
  • Like most multicellular organisms, have specialised cells. 
  • However, they don't posses true tissues…

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