Gemmule

A gemmule is a structure produced by some sponges for asexual reproduction. Gemmules are internal buds found in sponges and are involved in the process of regeneration and reproduction. They are typically formed in response to adverse environmental conditions, such as changes in temperature or water quality, and allow the sponge to survive until conditions improve.

Structure

Gemmules are composed of a mass of archaeocytes, which are specialized cells capable of developing into any other cell type. These cells are surrounded by a protective layer of spicules, which are made of silica or calcium carbonate. The spicules provide structural support and protection against predators and harsh environmental conditions.

Formation

The formation of gemmules begins with the aggregation of archaeocytes in the sponge's mesohyl, a gelatinous matrix within the sponge body. These cells then become surrounded by a tough outer layer composed of spicules and spongin, a type of collagen protein. Once fully formed, gemmules are released into the surrounding water or remain within the parent sponge until conditions become favorable for growth.

Function

Gemmules serve as a means of asexual reproduction and survival for sponges. When environmental conditions become unfavorable, the parent sponge may die, but the gemmules can remain dormant for extended periods. Once conditions improve, the gemmules can germinate, releasing the archaeocytes, which then differentiate into various cell types and form a new sponge.

Significance

The ability to produce gemmules allows sponges to colonize new areas and survive in environments with fluctuating conditions. This reproductive strategy is particularly important for freshwater sponges, which often face more variable conditions than their marine counterparts.

Related Pages

• Sponge
• Asexual reproduction
• Archaeocyte
• Spicule
• Regeneration (biology)
• Porifera