kiertäimet

Kiertäimet, also known as rotifers, are a phylum of microscopic, aquatic invertebrates. They are characterized by a crown of cilia on their anterior end, which they use for locomotion and feeding. This ciliated crown, called a corona, often resembles a rotating wheel, hence the name "rotifer" which means "wheel-bearer" in Latin. Rotifers are found in virtually all aquatic environments, from freshwater lakes and ponds to brackish and marine waters, and even in damp terrestrial habitats like mosses. They are typically small, ranging from 50 to 500 micrometers in length. Their bodies are unsegmented and usually possess a distinct head, trunk, and foot. The foot often has adhesive glands for attaching to surfaces. Internally, they have a complete digestive system, a nervous system, and a unique hydrostatic skeleton. Many species reproduce by parthenogenesis, where females produce offspring without fertilization, though sexual reproduction also occurs. Rotifers play an important role in aquatic ecosystems as both herbivores and detritivores, and as a food source for larger invertebrates and small fish.