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In this article we will discuss about the structure of Physalia with the help of a diagram.
1. It is a colonial sponge. The colony bears a transparent bluish or pinikish balloon-like large float or pneumatophore at the top.
2. The pneumatophore floats above the surface and the whole colony remains inside water.
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3. A pair of gas glands are located on the lower side along the inner surface and are responsible for floating of the colony.
4. The gas glands secrete gases similar in composition as air. The gas is a mixture of 90%; 1.5-3.5% 02 and other gases 5-7%.
5. The colony is polymorphic and is comprised of bunches of zooids comprising of a large gastrozoid in the centre, a few gonozoids along the base of gastrozoid and numerous dactylozoids around the gastrozoid.
6. The gastrozoid has a distinct mouth but no tentacles and is the nutritive zooid.
