Difference between Pinacoderm and Choanoderm

Pinacoderm and choanoderm are layers of cells unique to sponges belonging to the Phylum Porifera. Sponges are multicellular organisms that do not have specialised organs for respiration, digestion or circulation. They have a hollow body lined by specialised cells. Read further to know the differences between pinacoderm and choanoderm.

Refer: Characteristics & Examples Of Phylum Porifera

What Is Pinacoderm?

Pinacoderm is an outer layer of cells made up of pinacocytes in sponges that is almost equivalent to the epidermal layer of other animals. The pinacocytes are flat epithelial cells that form a squamous sheet on the outer surface and canals of sponges. This layer of cells serves as an external barrier to protect the underlying cells from the outer environment.

They are nucleated T-shaped cells. The pinacoderm has small inhalant apertures called ostia and large exhalant apertures called oscula. The cells are thin and broad. Based on their location and morphology, there are a few different types of pinacocytes known, exopinacocytes (layering the outer surface), endopinacocytes (layering the internal canals), basopinacocytes (those that form the base of sponges), prosopinacocytes and apopinacocytes.

What Is Choanoderm?

Choanoderm is a layer of cells called choanocytes that are flagellated cells. Choanocytes are cells that have a single flagellum that is surrounded by a net-like collar of microvilli. The choanocytes perform two major functions in the sponges, it creates a flow of water inside the body and captures food particles.

The choanoderm covers the inner surfaces of the sponge body. Some sponges possess choanocyte chambers which directly connects with the exhalant and inhalant canal.

Pinacoderm vs. Choanoderm




Pinacoderm is a layer of cells that cover the external surfaces of sponges.

Choanoderm is a layer of cells that cover the internal surfaces of sponges.

Cell Composition

It is made up of pinacocytes.

It is made up of choanocytes.

Cell Structure

The pinacocytes are nucleated, flat and broad cells that form a T-shape.

The choanocytes are flagellated cells that are covered with a collar of microvilli.

Surface Coverage

It covers the external surfaces of the sponges.

It covers the internal surfaces of the sponges.


It forms an external barrier for underlying cells.

It functions to create a water flow and also captures food particles.

Explore BYJU’S Biology for more information.

Also Read:

Frequently Asked Questions on Difference between Pinacoderm and Choanoderm


What is the function of pinacoderm?

The pinacoderm forms an external barrier on the surface and canals of sponges to protect it from the outer environment.


What are the four main types of cells found in sponges?

Sponges do not have determined organs in their body. They have four specialised cells called choanocytes, amoebocytes, pinacocytes and porocytes that perform all bodily functions.


What do poriferans eat?

Poriferans are primary feeders that consume microorganisms, organic debris and dissolved organic substances.


Who eats sponges?

Sponges are consumed by sea turtles and nudibranchs.


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