An open-ocean squid that comes up at night and glides above the surface on flared fins to escape.
Mantle 12 to 25 cm in the ordinary form, but giant equatorial individuals reach 72 to 82 cm. That is a real difference between forms rather than a disagreement between sources. The medium form carries a patch of light organs on top of the mantle; smaller forms do not.
The Humboldt squid has no dorsal light patch.
It spends the day below six hundred metres and rises to twenty or twenty-five at night, which is why it belongs to blackwater and night drift diving rather than to any reef. It moves in shoals of two to eight hundred. Total biomass is estimated at eight to eleven million tonnes and it is commercially significant.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
