Sponges are suspension feeders that lack true tissues, though they have a few specialized cells.

• Epidermal cells form a outer layer of tightly packed calls called the epidermis.

• Porocytes allow water to enter a cavity (spongocoel) and out through the Osculum.

• Choanocytes beat their flagella to draw water in from the porocytes through its collar.

• Amoebocytes transport nutrients to other cells and also secrete the spicules.