EVERYDAY SCIENCE

Detailed explanation-1: -The mesohyl, formerly known as mesenchyme or as mesoglea, is the gelatinous matrix within a sponge. It fills the space between the external pinacoderm and the internal choanoderm.

Detailed explanation-2: -The plasma membrane is the border between the interior and exterior of a cell. As such, it controls passage of various molecules-including sugars, amino acids, ions, and water-into and out of the cell.

Detailed explanation-3: -These spicules serve to provide additional stiffness to the body of the sponge. Additionally, spicules, when present externally, may ward off predators. Another type of protein, spongin, may also be present in the mesohyl of some sponges.

Detailed explanation-4: -The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges.