choanocyte

biology

Also known as: collar cell

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Last updated

June 24, 2026

Quick Summary

Choanocytes, also known as collar cells, are specialized cells found in sponges. Each choanocyte has a flagellum surrounded by a collar of cytoplasm. The flagellum's movement creates a water current that draws food particles into the collar, where they are captured. These captured food particles are then transferred to other cells within the sponge for digestion. Choanocytes are crucial for the sponge's feeding and water circulation systems. They are also remarkably similar in structure to choanoflagellates, a type of protozoan.1234

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reproductive behaviour
Protozoans and sponges
…up by specialized cells called choanocytes and carried to the egg. Fertilization takes place when a choanocyte fuses with the egg. The free-swimming larval stage that is produced is of short duration, after which the organism settles on the bottom and becomes a new adult sponge.
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…up by specialized cells called choanocytes and carried to the egg. Fertilization takes place when a choanocyte fuses with the egg. The free-swimming larval stage that is produced is of short duration, after which the organism settles on the bottom and becomes a new adult sponge.
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sponge
Sexual reproduction
…specialized flagellated cell called a choanocyte, or collar cell, in another sponge. The choanocyte then transforms into an amoeba-shaped cell called a carrier cell, which gives up the spermatozoan to an egg, lying near a chamber formed by choanocytes and containing long lashlike appendages called flagella.
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…specialized flagellated cell called a choanocyte, or collar cell, in another sponge. The choanocyte then transforms into an amoeba-shaped cell called a carrier cell, which gives up the spermatozoan to an egg, lying near a chamber formed by choanocytes and containing long lashlike appendages called flagella.
Read More