Two centimetres long, and it glues itself to the underside of a weed blade.
Among the smallest cephalopods in the world, mature at about 1 cm and rarely exceeding 2. The body is a short transparent cylinder with small round fins near the rear, the whole animal so clear that the internal organs and the eyes are the most visible parts. Chromatophores fire across the surface in single dots, which at this size is visible only through a macro lens.
The distinguishing feature is on the back. A glandular patch on the upper mantle secretes an adhesive that lets the animal stick itself, usually upside down, to the underside of a seagrass blade or a piece of weed, where it hangs motionless waiting for mysid shrimps. It is one of very few cephalopods that attaches itself to anything. Found in the top few metres over seagrass and weed, almost always at night, and almost always by a guide who knows which patch of weed. Life span is a few months. Photographing one is a matter of the tiniest subject on this list against a blade that moves with every surge.
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.
