What is gemmules? Give examples.

Hint: An asexually produced mass of cells capable of developing into a new organism or an adult freshwater sponge is referred to as a Gemmule.A freshwater sponge reproduces both sexually and asexually.

Complete answer:
They are small bud-like cells formed by sponges to withstand unfavourable environmental conditions. Asexual reproduction is mainly by budding and also by gemmulation. The inner buds formed by freshwater sponges are called gemmules. These gemmules are hard and coated with a dormant cluster of embryonic cells. Freshwater sponges are multicellular, marine living species of the Kingdom of Phylum – Porifera. Sponges, Ficulina ficus, sea sponges and much more are the species of this kingdom. All species are related to the same kingdom and have the same characteristics.

Internal buds, gemmules, are resistant to dehydration, freezing and can survive even without the supply of oxygen. The outer layer of the gemmule is enclosed and protected by an endospore surrounded by a layer of spicules that helps the gemmule out of all other unfavourable environmental conditions and also helps the gemmules grow into an adult freshwater sponge.

Gemmules are typically found in a round or ball-like structure, along with a central mass of amoeboid cells and a thick peripheral layer of a small siliceous spicule.Micropyle, Spicule, Inner Layer, Archaeocyte, and Outer Pneumatic Layer make up the structure of Gemmules.The micropyle is the outer layer of a cell with a minute opening and the outer layer is made up of a thick pneumatic layer and air chambers that help gemmules to float in water bodies. The spicule is a sharp-pointed structure that protects the gemmules from predators while also providing structural support. Archaeocytes are reproductive cells, and the spicule is a sharp-pointed structure that helps protect the gemmules from predators.

Note: Gemmule is produced by a few species of freshwater sponges such as Spongilla and some marine species, including ficulina ficus, sea sponges and other porifera species, which produce gemmules to survive under unfavourable conditions and to germinate and produce new sponges.