Difference Between Choanocytes and Pinacocytes

Choanocytes are body cells of sponges and pinacocytes are flat shaped cells that make up the pinacoderm of sponges. The key difference between choanocytes and pinacocytes is that choanocytes contain flagella while pinacocytes do not contain flagella.

Spongiology is the branch of biology that focuses on the study of sponges. Sponges belong to the phylum Porifera. They are multicellular organisms that have pores in the body which facilitate water circulation.

CONTENTS

1. Overview and Key Difference
2. What are Choanocytes
3. What are Pinacocytes
4. Similarities Between Choanocytes and Pinacocytes
5. Side by Side Comparison – Choanocytes vs Pinacocytes in Tabular Form
6. Summary

What are Choanocytes?

These are cells that line the interior of sponges that include all three body type groups: asconoid, syconoid, and leuconoid. They all possess flagella. Choanocytes closely resemble choanoflagellates and generate a flow of water during movement. And thus, help the sponges to accumulate high amount of oxygen and nutrients. Furthermore, it improves the respiratory and digestive functions. Its other functions include carrying out ingestion and exporting digested materials to amoebocytes.

Though sponges do not contain reproductive organs, the choanocytes possess the unique ability to convert to spermatocytes when needed for sexual reproduction. The spongocoel of asconoid sponges and radial canals of syconoid sponges contain these cells. Further, in leuconoid sponges, these cells are present in chambers.

What are Pinacocytes?

Pinacocytes are flat cells present in the outer most cell layer of sponges. They do not have a flagellum. Pinacoderm is the common name for the outermost cell layer of these cells. Furthermore, there are three main types of these flat cells. They are, basipinacocytes (in contact with the surface to which the sponge is attached), exopinacocytes (cells on the surface of the sponge), endopinacocytes (cells that line the canals of the sponge).

Further, these cells possess many granules that are capable of contraction. Moreover, these flat cells maintain the size and structure of the sponge through contraction and relaxation.

What are the Similarities Between Choanocytes and Pinacocytes?

• Choanocytes and Pinacocytes are cells that belong to the phylum Porifera.
• Both cells are present within the body of sponges.

What is the Difference Between Choanocytes and Pinacocytes?

Summary – Choanocytes vs. Pinacocytes

Sponges belong to the phylum Porifera. Choanocytes are cells with a flagellum while pinacocytes make up the pinacoderm of sponges. Both provide important cellular advantages to the sponge. Choanocytes help in accumulating oxygen and nutrients while pinacocytes provide a shape to the body through contraction and relaxation. This is the key difference between choanocytes and pinacocytes.

Reference:

1. “Choanocyte.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
2. “Choanocytes.” Sciencentre, Available here.
3. “Pinacocyte.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.

Image Courtesy:

1. “Image from page 108 of “The Porifera and coelentera” (1900)” by Internet Archive Book Images via Flickr (No known copyright restrictions)
2. “Aplysina archeri (Stove-pipe Sponge-pink variation)” By Nhobgood (talk) Nick Hobgood – Own work (CC BY-SA 3.0) via Commons Wikimedia