pneumatophore

A pneumatophore is a specialized structure with two primary functions. In wetland plants like mangroves, it's an upward-growing root that protrudes above mud or water to facilitate oxygen intake and gas exchange for submerged roots. In certain marine colonies called siphonophores, a pneumatophore is a gas-filled sac that acts as a float, allowing the colony to maintain buoyancy.123

A cnidarian zooid refers to an individual within a colonial cnidarian. These colonies can exhibit polymorphism, where different zooids are specialized for specific functions such as feeding, defense, or reproduction. For example, in the order Siphonophora, specialized zooids include pneumatophores for flotation, nectophores for movement, and bracts for protection.3