Long-distance dispersal

Dispersal by dormant stages

Many animal species, especially freshwater invertebrates, are able to disperse by wind or by transfer with the aid of larger animals (birds, mammals or fishes) as dormant eggs, dormant embryos or, in some cases, dormant adult stages. Tardigrades, some rotifers and some copepods are able to withstand desiccation as adult dormant stages. Many other taxa (Cladocera, Bryozoa, Hydra, Copepoda and so on) can disperse as dormant eggs or embryos. Freshwater sponges usually have special dormant propagules called gemmulae for such a dispersal. Many kinds of dispersal dormant stages are able to withstand not only desiccation and low and high temperatures, but also the action of digestive enzymes during their transfer through digestive tracts of birds and other animals, high concentration of salts, and many kinds of toxicants. Such dormant-resistant stages have made possible the long-distance dispersal from one water body to another and broad distribution ranges of many freshwater animals.