This work aims to study nectophores growth of Muggiaea atlantica and Muggiaea kochi and their eudoxids. Data obtained reveal that the maximal average numbers of M. atlantica & M. kochi nectophores were encountered during May when the
surface temperature was raised (20.22 0C) and surface salinity decreased (37.55 ‰). On the other hand, the least numbers recorded were encountered during March where surface temperature was lowered (13.20 0C) and surface salinity increased (38.37‰). Average lengths of M. atlantica & M. kochi nectophores tend to increase during
March & April (3.19 mm & 2.93 mm, respectively), and decrease during May & June (2.78 mm & 2.73 mm, respectively). As might be expected from the small size of the adult colonies, the appearence of blooms of Muggiaea atlantica & Muggiaea kochi during May and June indicates that the life-cycle is short at temperature I9 0C while it is longer at 13 0C as shown during March and April. Therefore, life cycle of this coelenterate is strictly temperature dependent.