Pelagic cephalopods seem to occupy a variety of habitats within this zone. Abralia trigonura Berry inhabits the zone only as adults; A. astrosticta Berry may inhabit the inner boundary zone, and Pterygioteuthis giardi Fischer appears to be a facultative inhabitant. Three other mesopelagic species, Liocranchia reinhardti (Steenstrup), Chiroteuthis imperator Chun, and Iridoteuthis iris (Berry), are probable inhabitants; the latter two are suspected to be nonvertical migrants. The mesopelagic-boundary region also contains a variety of other pelagic cephalopods.