A large amphipod that is entirely transparent, and whose head is almost all eye.
A hyperiid amphipod that reaches about 15 cm, far larger than the rest of the group, and so completely transparent that in a light the animal reads as a shape in the water rather than as a body. The gut and a pair of orange-red retinas are the only parts that hold colour. The head is taken up almost entirely by the eyes: two enormous compound eyes lie flat under the top of the head, looking upward, with the retinal tissue spread out beneath them. An animal seen from above appears to have a flat plate for a face.
Everything about it is arranged for a life spent looking up into faint downwelling light for the silhouettes of prey. The transparency is defensive and is unusually complete; the leg and body surfaces carry a fine layer of nanoscale structures that cut reflection, so the animal does not give itself away as a glint when a predator’s light or a diver’s beam crosses it.
It lives in the mesopelagic, several hundred metres down, and is met on blackwater dives when it comes up at night. Handling and current damage it easily, and animals that have been in the beam of several cameras drift away deformed, which is an argument for one photographer at a time. Species within the genus are not separable in the water.
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.
