EVERYDAY SCIENCE

Detailed explanation-1: -Spongin, a modified type of collagen protein, forms the fibrous skeleton of most organisms among the phylum Porifera, the sponges. It is secreted by sponge cells known as spongocytes. Spongin gives a sponge its flexibility.

Detailed explanation-2: -The skeletal elements of the sponge are produced by the amoebocytes. The amoebocytes produce spongin, the soft fiber that forms natural bath sponges. These sponges feel soft and springy to the touch because they have soft skeletons made of flexible fibrous spongin.

Detailed explanation-3: -Demosponges, which contain spongin and may or may not have spicules, constitute about 90% of all known sponge species, including all freshwater ones, and have the widest range of habitats.

Detailed explanation-4: -Spicules are often categorized by size, the larger being megascleres and the smaller microscleres. Some spicules are formed of the mineralized substances calcium carbonate and silica, while others are made of an organic substance called spongin.