Question

Asexual reproduction in sponges takes place with the help of
A. Multiple fission
B. Binary fission
C. Gemmule formation
D. Gemmae

Answer 1

Hint: Sponges are pore bearing animals and belong to phylum Porifera. They have cellular organization, cell aggregate plan and are mostly asymmetrical.

Complete answer:
Their(sponges) body wall is formed of two layers- outer dermal layer or pinacoderm of flat pinacocytes and inner gastral layer or choanoderm of flagellated collar cells or choanocytes whose flagella beat and maintain a water current.
Porifera have an endoskeleton of either calcareous spicules or siliceous spicules or of sponging fibres.
They are divided into three classes based on the endoskeletal elements:
Class Calcispongiae or Calcarea
Class Hexactinellida or Hyalospongiae
Class Desmospongiae
They have basically two types of pores- numerous and smaller ostia and one or few larger osculates which act as inlets and outlets of water currents. They have a peculiar canal system whose central cavity is called paragastric cavity or spongocoel.
Most sponges are bisexual or hermaphrodite or monoecious. Fertilization is internal and development is indirect and involves the formation of a free-swimming amphiblastula larva or parenchymella larvae.
Asexual reproduction occurs by fragmentation or external budding or gemmules.
Gemmule is an internal bud of the Spongilla which is a freshwater sponge. It is formed of a mass of archaeocytes surrounded by a coat of amphi disk spicules. It helps in perennation.
These act as spores of sponges while their formation is called gemmation. Gemmules are also found in some marine sponges, e.g. Ficulina, Tethya, etc.
So, the correct answer is “Option C”.

Note: Sponges are diploblastic animals and there are about 5000 living species of them. They are mostly marine but about 150 sponge species inhabit fresh water, e.g. Spongilla.