Micro-animal

• Microscopic arthropods, including dust mites, spider mites, and some crustaceans such as copepods and certain cladocera.
• Tardigrades
• Rotifers, which are filter feeders that are usually found in fresh water.
• Some nematode species
• Many loricifera, including the recently discovered anaerobic species, which spend their entire lives in an anoxic environment.