A highly characteristic genus of large (8-30mm) globular bathypelagic to benthopelagic species, which appears to be ubiquitous to all oceans. The species lack compound eyes, but the naupliar eyes are extremely well developed with large reflectors. They tend to be very fragile, since they regulate their buoyancy by excluding sulphate ions, so the carapace is uncalcified and the body is very watery. Females carry large broods of embryos inside the carapace in the space between the dorsal abdominal wall and the Inner lamella of the carapace. Many of the species are well pigmented with colours ranging from orange to purple-red. Generally these are unmistakable.
Poulsen, 1962 lists five species, two of which have been recorded from the region. G. muelleri can be very abundant in catches from 1000m, whereas G. draconovalis is confined to depths >3000m, but has been caught in large numbers very close to the seabed at depths of 2000m.