Question
Write an account on skeleton of sponges.
✓
Answer
The body of sponges contains a supporting exoskeleton. It is made up of either spicules or spongin fibres or both. Spongin fibres are protein fibres. They are either highly branched or show anastomosis. Spicules are calcareous or siliceous with hard spine-like structures.
- Depending on the branching the spicules are:
- Monoaxons (single axis).
- Triaxons (three axis forming six rays of hexactinal spicules).
- Tetraxons (four rays or tetra actinal).
- Polyaxons (several rays).
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