Our maps illustrate that there is a measure of coherence between the biogeochemical regions identified by Longhurst (1998). However, data based by presence and absence is probably not the best criterion for assessing such coherence since individual animals appear to be able to persist after being advected across boundaries, thus blurring the patterns. Using relative abundances of species can be expected to give clearer indications, assuming the halocyprids are responsive to the changes in the biogeochemical regime. We expect the principle oceanic fronts and flows will influence the distributions of some, if not all, species, and so the halocyprid species have the potential value to serve as biological markers and indicators. One example is Macroconchoecia caudate. This unmistakable species is quite common in the Indian Ocean but quite uncommon in the South Atlantic. A reasonable hypothesis is that its presence in the South Atlantic results from mesoscale eddies spawning from the Agulhas Retroflection advecting this species into the South Atlantic. Thus we postulate that the presence of the species indicates an Indian Ocean origin for the water body in which they are sampled.

The maps also reveal some inconsistencies in the data. For example when plotting the data for the Southern Ocean endemic Boroecia antipoda, a few records from tropical seas stood out as being anomalous. These records came from Poulsen’s (1975) analyses samples from the Dana Expedition that were collected outside the normal range of this species. We have re-examined the specimens and found them to belong to a new species, albeit very similar to B. antipoda. The Atlantic maps show a number of examples of disjunct distributions which may also be indicative of taxonomic problems. There is uncertainty about many early records for species that have subsequently been split, For example, Angel (1972) split Proceroecia procera into three, so records previous to 1972 could be of any (or all) of the three species. We have accepted all published records for which we have no objective reason to disregard the records, although some will be erroneous.