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: -Spongin fibers are fine threads consisting of a soft granular axial core externally surrounded by concentric layers of spongin. Spongin contains large amounts of iodine.

Detailed explanation-4: -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-5: -Spongin is the flexible material that makes up the body wall of the sponge, while spicules are hard, spiny secretions that help to provide a reinforced structure. The cells lining the inside of the sponge are called choanocytes (’collar cells’), which have a ‘tail-like’ flagellum.