ABSTRACT
This chapter talks about marine sponges. It is the simplest of the multicellular invertebrate animals, possess neither nervous system nor internal organs. Based on the composition of the skeletal elements, sedentary animals are divided into four classes: calcarea; hexactinellida; sclerospongiae; and demospongiae. Marine sponges vary greatly in their external appearance. Sponges create unidirectional water flow throughout their body to facilitate food and oxygen intake and send out the waste. This water enters the sponge through Ostia and leaves through a larger opening. Most sponges reproduce sexually, although asexual reproduction may also occur. Sponges are generally hermaphroditic. However, some sponge species are sequential hermaphrodites. The marine sponges gained great interest due to their association with a wide variety of microorganisms. These microorganisms are known to be a rich source of secondary metabolites that exhibit a broad range of bioactivities such as inhibition of enzyme activities and cell division, and antiviral, antimicrobial, anti-inflammatory, antitumor, cytotoxic, and cardiovascular properties.
