Final answer:
The Portuguese man of war maintains buoyancy with a gas-filled pneumatophore that regulates its position in water. This colonial organism is made up of specialized zooids that work together for tasks such as movement, feeding, and defense. Buoyancy results from the displacement of water by this gas-filled structure.
Step-by-step explanation:
The Portuguese man of war maintains buoyancy through a specialized structure called a pneumatophore, which fills with carbon monoxide gas. This float is part of its body and functions to regulate its position in the water. Contrary to single organisms, the Portuguese man of war is a siphonophore - a colony of multiple organisms working in union. These organisms, called zooids, have specialized functions for motility and buoyancy, feeding, reproduction, and defense, leveraging their combined abilities to survive.
Specifically, the gas-filled pneumatophore allows the colony to float on the surface and move with ocean currents, while it deploys tentacles laden with nematocysts for defense and capturing prey. Understanding buoyancy, in general, involves recognizing that an object submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object. This principle explains how the Portuguese man of war, despite being a free-floating entity in the ocean, achieves its buoyancy.