Abstract
The scavenging deepwater isopod Natatolana borealis (LILLJEBORG) was caught off Bergen on the West coast of Norway in baited traps. N borealis attained sexual maturity from 6-7 instar. The oostegites were formed in a biphasic parturial-ecdysis. FOllr marsupial instars were identified and described. The marsupia ofthe laboratory breeding females contained from 23 to 77 eggs, while the ovaries contained from 28 to 120 oocytes. The time needed for the development ofthe brood in the laboratory was estimated to be 3-4 months. Breeding females were not caught in the traps. Reproduction took place throughout the year with varying intensity. After the brood release the surviving females went into an intergenerative phase of breeding. The females could have 1-2 broods during lifetime.