Fragilaria are chain-forming diatoms that are joined side-by-side. Fragilaria crotonensis is very common in Lake Erie. F. crotonensis is only joined at the center of the cells. F. crotonensis can form very long chains that look like a ribbon twisting. Fragilaria capucina is common in the nearshore areas of Lake Erie where nutrients are higher. F. capuncina cells are completely joined along the edges.