spicule

Examples of spicule in the following topics:

• Phylum Porifera

  • Sponges lack true tissues, have no body symmetry, and are sessile; types are classified based on presence and composition of spicules.
  • The presence and composition of spicules and spongin are the differentiating characteristics between the classes of sponges .
  • Hemoscleromorpha sponges tend to be massive or encrusting in form and have a very simple structure with very little variation in spicule form (all spicules tend to be very small).
  • Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silica.
  • Sponges are classified based on the presence and types of spicules they contain.

• Pre-Cambrian Animal Life

  • They are believed to show the existence of hard body parts and spicules that extended 20–40 cm from the main body (estimated about 5 cm long).

• Types of Skeletal Systems

  • An example of a primitive endoskeletal structure is the spicule of sponges.

• Bone Remodeling and Repair

  • Some bone spicules may also appear at this point.

• Morphology of Sponges

  • Some of these more-specific cell types include collencytes and lophocytes, which produce the collagen-like protein to maintain the mesohyl; sclerocytes, which produce spicules in some sponges; and spongocytes, which produce the protein spongin in the majority of sponges.

• Physiological Processes in Sponges

  • In gemmules, an inner layer of amoebocytes is surrounded by a layer of collagen (spongin) that may be reinforced by spicules.

• Phylum Nematoda

  • Specialized structures at the tail of the male keep him in place while he deposits sperm with copulatory spicules.

• Classification of Phylum Mollusca

  • These animals lack a calcareous shell, but possess aragonite spicules on their epidermis.