Hadal cephalopods: first squid observation (Oegopsida, Magnapinnidae, Magnapinna sp.) and new records of finned octopods (Cirrata) at depths > 6000 m in the Philippine Trench

During a manned submersible dive in the Philippine Trench, a solitary oegopsid squid of the monogeneric family Magnapinnidae was observed swimming close to the seafloor at 6212 m. The estimated mantle length of the squid was ca. 10 cm. The long slender terminal arm and tentacle filaments characteristic of adult Magnapinna were not obvious in the video. The filaments may have been contracted or may not yet have developed. This observation is the first record of squid at hadal depths and extends the known bathymetric range for any squid by 1477 m; an increase of ca. 30%. We also observed four cirrate octopods between 6212 and 6224 m. Although the video quality was poor, these octopods did not appear to be the same species as those reported previously in the Java Trench. These observations extend the known hadal occurrence of cirrates, and cephalopods in general, from the Indian Ocean to the equatorial North Pacific Ocean, suggesting that their global presence in depths > 6000 m may be more extensive than previously recognized.