Poymius

Poymius is a genus of small deep-sea cephalopods described in the early 2010s, currently containing a single described species, Poymius abyssalis. Members are distinguished by a translucent mantle, two short fins, and a network of bioluminescent organs along the mantle, arms, and auxiliary fins. The genus is of interest for studies of deep-sea adaptation and bioluminescence.

Taxonomy and naming. It belongs to the family Poymiidae within the order Sepiolida of subclass Coleoidea, class Cephalopoda. The name Poymius is derived from roots intended to evoke variability in pigmentation and depth; the epithet abyssalis refers to its abyssal depth habitat.

Description. Size mantle length 2–3 cm; eight arms with small suckers; skin semi-transparent with visible internal organs in life. The dorsal surface bears photophores capable of blue-green light. The animal shows rapid color modulation through chromatophores for camouflage.

Distribution and habitat. Known from the western Pacific, around seamounts and submarine canyons at depths of roughly 800–1,500 meters. Prefers cold, low-light, high-pressure environments.

Biology and ecology. Diet consists of tiny crustaceans and polychaetes; predation is likely ambush-based. Solitary and primarily nocturnal. Reproduction involves females laying gelatinous egg capsules attached to the substrate; males use a modified arm to transfer spermatophores.

Discovery and status. Collected during deep-sea expeditions in 2009–2010 and described in 2012 by Ito and Singh. Current knowledge is limited; the species is not evaluated by major conservation bodies, and its deep-sea habitat faces threats from mining and pollution.