| abstract | The number of halacarid genera and the approximate number of species in deep and shallow waters are listed, together with the halacarid species recorded from depths of over 1000 m. The vertical and horizontal distribution of genera are discussed, as well as morphological adaptions to life in the abyss. Eurybathic species are rare, and endemic deep-sea genera presumably do not exist. Algibiont and arenicolous genera have not been found in the abyss. Striking morphological features such as long legs, epimeral and anal protuberances, and dense coatings with cuticular filaments are independent of water depth and hydrostatic pressure, but correlate with life in very soft sediments. The deep-sea species, Lohmannella cygna nov. spec., is described. |