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Freshwater Bryozoans of Virginia

 

This guide to the Freshwater bryozoans of Virginia is a work in progress.  So far collections are limited to  sites in the southern part of the state.   So far 9 species have been found (about two dozen or so species known from the United States).  Although freshwater bryozoans are much less diverse than their marine relatives, they are sometimes very common and (in the case of  one species, Pectinatella magnifica) large enough to attract public attention.  There are two groups of bryozoans that live in freshwater.  Most species belong to the order Phylactolaemata.  A very few species of ctenostome bryozoans (members of the order Gymnolaemata, most of which are marine or estuarine) also occur.

Habitats

There are two basic kinds of freshwater habitat, lentic, flowing water, as in streams and rivers and lotic, non-flowing, as in ponds, lakes, and reservoirs.  Freshwater bryozoans may be found in both, but some species are much more characteristic of one than the other.

Identification

The most important characteristics used in distinguishing freshwater species are the shape of the lophophore, round or horseshoe shaped, the form of the colony, and (because this can vary with habitat and stage of growth) the shape of the resting stages called statoblasts that colonies may contain.  These are distinctive to each species and provided the most accurate means to distinguish different species. 

 

Species List

The following species have been found so far.

Phylactolaemates

    Fredericella indica

    Plumatella repens

    Plumatella emarginata/casmiana

    Hyalinella punctata

    Pectinatella magnifica

Ctenostomes

    Paludicella articulata

    Pottsiella erecta

Descriptions

An illustrated description of each is given below.

Fredericella indica

Plumatella repens

Plumatella emarginata/casmiana

Hyalinella punctata

Pectinatella magnifica

Paludicella articulata

Pottsiella erecta