SPONGES

Sponges enjoy shadows or darkness as they can only tolerate a small amount of light. They do not like water with a high content of nitrates or filamentous algae, which smother them. They reproduce, either sexually - rarely achieved in an aquarium - or through asexual division, with a detached piece of sponge evolving into a new specimen.

A sponge is a kind of "sack" devoid of any specialized organs. Water penetrates the walls, circulates in the canals, as a result of the movements of thousands of strands protecting the cells, and leaves via the opening in the top. The water provides oxygen and the particles on which the sponge feeds, particularly the micro-algae of phytoplankton.

Removing a sponge from water has fatal consequences, as air bubbles enter the canals where the water circulates and block them. The sponge, unable to eliminate the bubbles, eventually dies.

Sponges are fed in the same way as Coelenterates, with a preparation based on mussels, or special liquids available commercially from specialist suppliers.