Gemmule

This article is about the internal buds of freshwater sponges. For the proposed mechanism of heredity, see pangenesis.

Gemmules are internal buds found in sponges and are involved in asexual reproduction. It is an asexually reproduced mass of cells, that is capable of developing into a new organism i.e., an adult sponge.

Role in asexual reproduction

Asexual reproduction in sponges occurs via budding, either by external or internal buds. The internal buds are called gemmules. Only endogenous types of buds develop into new sponges.

Characteristics

Gemmules are resistant to desiccation (drying out), freezing, and anoxia (lack of oxygen) and can lie around for long periods of time. Gemmules are analogous to a bacterium's endospore and are made up of amoebocytes surrounded by a layer of spicules and can survive conditions that would kill adult sponges. When the environment becomes less hostile, the gemmule resumes growing.