👉 The term "hydrophilidae" refers to a group of marine invertebrates that are characterized by their ability to swell and expand when they come into contact with water. This characteristic is often referred to as "water buoyancy." The order Hydrophilidae includes several families, including the Siphonophora, which are known for their ability to absorb sunlight and create a natural light source in the dark sea. These invertebrates are also found in saltwater environments and have been