Siphonozooids

Siphonozooids are specialized polyp individuals found in siphonophores, which are colonial marine animals belonging to the phylum Cnidaria. Siphonozooids are distinct from other zooids within the colony, such as pneumatophores (float), nectophores (swimming bells), and gastrozooids (feeding polyps). Their primary function is related to the circulation of fluids within the colony.

These structures are essentially highly modified gastrozooids that have lost their digestive and mouth structures. Instead, they possess a prominent mouth that opens into a central canal system, known as the gastrovascular canal. This canal system runs throughout the entire siphonophore colony. Siphonozooids actively pump water and nutrients into this canal system, ensuring that all zooids within the colony receive the necessary resources for survival and growth.

The pumping action of siphonozooids is crucial for maintaining the integrity and functionality of the siphonophore colony. By facilitating the distribution of digested food and other essential substances, they contribute significantly to the overall colonial metabolism and coordination. The exact number and arrangement of siphonozooids can vary depending on the specific species of siphonophore. Their unique morphology and function highlight the complex organization and division of labor characteristic of siphonophore colonies.