The following contributions are part of a more comprehensive project
dealing with the constructional morphology of "secondary soft bottom
dwellers". These are aquatic organisms of various affiliations, that earlier
in their phylogenetic history had become sessile suspension feeders on hard
rocky bottoms. Their inherited loss of active mobility became the main
handicap in getting established in soft bottom environments, because it
not only blocked active burrowing (see previous contribution by JEFFERIES,
SAVAZZI & SIGNOR), but it also made special adaptations necessary to maintain
and restore the suitable life position. Five basic strategies can be
distinguished in secondary soft bottom dwellers: