This article is about the skeletal structure. See also
Spicule (solar physics). Spicules are
skeletal structures that occur in most
sponges. They provide structural support, as well as deterrence against
predators. Large spicules, visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. Spicules have four major symmetry types: Monaxon (simple cylinders with pointed ends), triaxon, tetraxon, and polyaxon. Sponges can be
calcareous,
siliceous, or composed of
spongin. The meshing of numerous spicules serves as the sponge’s skeleton. The composition, size, and shape of spicules is one of the largest determining factors in sponge
taxonomy.
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SPICOLE. SPIGHE SECONDARIE. SPIGHETTE