This taxon is typically found in marine plankton assemblages, but may also occur in littoral regions of the oceans. Specimens found in the Great Lakes are almost certainly either fossil, derived form diatomites used as filtration media, etc., or anomalous occurrences derived from accidental transport by birds or ocean-going ships. It is extremely doubtful that any members of this genus presently grow in the Great Lakes (Hendey 1964).