NEET BIOLOGY

Detailed explanation-1: -Sponge skeletons are made of rod-like silica structures called spicules that are cemented to rocks and to each other with collagen.

Detailed explanation-2: -Tentacles surround mouth and have stinging cells (cnidocytes) containing stingers (nematocysts).

Detailed explanation-3: -The skeleton of Sycon is made up of spicules that arise from the scleroblasts and are organized to safeguard the delicate parts. A common observance is the presence of tetraradiate or triradiate spicules. The mesenchyme is composed of a gelatinous proteinaceous matrix containing spicules and many amoeboid cells.

Detailed explanation-4: -Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.