Hydromedusa refers to the free-swimming stage of certain jellyfish, particularly those in the class Hydrozoa. Unlike their sessile polyp stage, hydromedusae are typically bell-shaped and possess tentacles that help them capture prey. They are often found in marine environments and can vary in size and color. These organisms play a crucial role in aquatic ecosystems, serving as both predators and prey. Hydromedusae feed on small planktonic organisms and, in turn, are consumed by larger marine animals, such as fish and sea turtles. Their life cycle includes both the medusa and polyp stages, contributing to their ecological significance.