GENERAL HISTOLOGY

Detailed explanation-1: -All adult sponges are sessile, meaning they live permanently attached to rocks or other submerged objects and do not move about on their own. Some sponges grow in thin encrusting layers over surfaces (Fig. 3.18 A).

Detailed explanation-2: -All adult sponges are sessile aquatic animals, meaning that they attach to an underwater surface and remain fixed in place (i.e., do not travel) while in larval stage of life they are motile.

Detailed explanation-3: -Sponges are sessile, meaning they cannot move, they filter water to obtain their food. They don’t have brains, stomachs, or other organs. They do not even have true tissues. Instead, their bodies are made up of specialized cells (cell-level organization) that do specific jobs.

Detailed explanation-4: -Sponges are very primitive organisms that are made of cells, but their cells are not organized into true tissues. They have an irregular body shape, lacking any type of symmetry, and they are not segmented. Sponges also have no pseudocoelom, which is an internal body cavity.

Detailed explanation-5: -Adult sponges are basically sessile, meaning that they are immobile. But some marine and freshwater species can move very slowly across the sea bed as a result of amoeba-like movements of cells. A few species can contract their whole bodies, and many can close their small mouth-like apertures, or oscula, and the ostia.