spicule

(noun)

a sharp, needle-like piece

Related Terms

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.