In situ observations of Stygiomedusa gigantea

The resulting dataset confirms that this species is cosmopolitan occurring with records from all Oceans except the Arctic. While the depth range of the four Gulf of Mexico specimens was bathypelagic, there appears to be a pattern of S. gigantea occurring in mesopelagic and epipelagic depth zones at high latitudes, particularly in the Southern Ocean and mesopelagic and bathypelagic depths at mid- and low-latitudes. This pattern may be related to the meridional vertical distribution of temperature or perhaps avoidance of light levels that could degrade porphyrin pigments.

There was no evidence that this species migrates vertically. Two of the individuals in the Gulf of Mexico appeared to be actively clinging to subsea structures and we speculate that this is a consequence of its normal mode of feeding which may entail using its large oral lobes to hold on to, and trap prey.