Gastrotricha

Gastrotricha are microscopic aquatic animals that belong to the phylum Gastrotricha. They are commonly known as hairy bellies due to the presence of cilia on their ventral surface, which they use for locomotion. These tiny creatures, typically measuring between 0.05 and 0.3 millimeters in length, inhabit a wide range of aquatic environments, including freshwater, marine, and brackish waters. They are often found in interstitial spaces of sediments, such as sand and mud, as well as on submerged vegetation.

The body of a gastrotrich is elongated and unsegmented, with a distinct head region and a tail. They possess a complete digestive system and exhibit sexual reproduction, with most species being hermaphroditic or parthenogenetic. Gastrotrichs are detritivores and feed on bacteria, algae, protozoa, and other organic matter. Their small size and simple body plan make them an interesting subject for studying the evolution of metazoans. Despite their ubiquity, gastrotrichs are often overlooked due to their minuscule size and the challenging nature of their collection and study. Their ecological role, though small, contributes to the nutrient cycling and decomposition processes in their respective habitats.