J
jennifer
Guest
Hi Pamela, many microscopic aquatic animals have some kind of "hibernating" phase. This allows them to survive if their pond dries up, and allows them to spread from pond to pond in a dry form. For example, daphnia (aka "water fleas") form ephippia, which are basically small dry seed-like specks, which can stay dry for years, then spring back to life when soaked. Some nematode worms have a dauer form, which can also survive for years dry. This is how such critters could, conceivably, travel into our houses on dirt from outdoors.