Sponge Anatomy

Sponges, belonging to the phylum Porifera, are simple multicellular organisms with a unique body plan. They lack tissues and organs but possess specialized cells that perform various functions.

The outer layer of the sponge is the ectoderm. Sponges have numerous tiny pores called ostia on their outer surface. These pores lead into a system of channels and chambers that make up the sponge's body. Water enters the sponge through the ostia and flows through the channels, carrying oxygen and food particles while removing waste products. Water flows out of the sponge through a larger pore called the osculum.

Choanocytes are specialized cells lining the inner surface of the sponge's body. They have a distinctive collar of microvilli surrounding a flagellum. The flagellum creates water currents, drawing water through the sponge. Amoebocytes are amoeba-like cells that move within the body, and are involved in nutrient digestion.

Some sponges have structural elements within called spicules. Spicules provide support and protection to the sponge's body, helping to maintain its shape.

Label the Sponge:


Ostia | Osculum | Choanocyte | Ectoderm | Amebocyte | Spicule

Related Activities

Google Slides on Sponges and Cnidarians

Color a Sponge

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