Nemertina
Vertical profiles and hydrographic data

There are few accurate data on the depth distribution of bathypelagic nemertines, principally because so many of the early records were made from specimens collected in nets which were hauled open to the surface. Brinkmann (1917a) concluded that Nectonemertes mirabilis lived in a fairly well defined layer of water where the temperature was 6ºC or less and the salinity did not exceed 35%o , this layer occurring at depths of 500-2000 m between Newfoundland and Ireland in the North Atlantic where this species was collectedNe 4.

Collections of pelagic nemertines made between 1980-1983 by the Amsterdam Mid North Atlantic Plankton Expeditions (AMNAPE), however, both yielded hydrographic data and enabled Van der Spoel (1985) to further analyse the vertical distribution of Nectonemertes mirabilis in detail. He found that Nectonemertes mirabilis at latitudes north of 41ºN lives at rather shallow depths of about 300 m during the winter, whereas at other times of the year it descends to 500 m or deeper. At depths of less than approximately 1750 m the species reaches further south in spring than in summer, whereas its northernmost abundance is highest during the autumn. Near 55ºN its uppermost distribution appears to follow the 9ºC isotherm. Shallow (approximately 25-100 m depth) summer night samples may illustrate vertical migration. Van der Spoel (1985: 21) concludes that pelagic nemertines "as a group, are bathypelagic animals with an upper limit of distribution between 500 and 1000 m depth." Depth data for species recovered during the AMNAPE cruises are summarised inNe 5.

Data on the nemertines found in the South Atlantic are sparse; they are accordingly listed with the species descriptions.