Mastigophores

Mastigophores are a type of zooid found in certain colonial hydrozoans, a group of marine invertebrates. These zooids are specialized for locomotion and defense. Their defining characteristic is the presence of a long, whip-like appendage, known as a mastigophore or flagellum, which they use to propel the colony through the water or to deter predators. Mastigophores are typically sterile zooids, meaning they do not reproduce.

These specialized structures are often found alongside other types of zooids within the colony, such as gastrozooids (for feeding) and gonozooids (for reproduction). The mastigophore's whip-like structure can be extended and retracted, and it may also possess stinging cells (nematocysts) similar to those found on tentacles of other cnidarians, providing an additional defensive capability. The exact structure and function of mastigophores can vary depending on the specific species of hydrozoan. Their presence contributes to the overall survival and mobility of the colonial organism.