A shrimp you can read a text through. Three centimeters (1.2 in) of glass with a few white and violet lines, sitting on an anemone or a soft coral, its gut and eggs the only clearly visible parts of it.
Transparency is a defense with a cost. It works well in open water where there is nothing to cast a shadow against, and much less well on a host - which is why these shrimps also spend their lives on animals nothing wants to bite. Between the two, the shrimp is effectively unreachable.
Finding one is a matter of looking at hosts rather than at the reef. Work over an anemone slowly with a torch and the shape resolves out of the background: first the eyes, then the gut, then the animal. This is the group macro photographers spend whole dives on, and it is why the same coral head repays a second visit.
It feeds on detritus and mucus from the host and takes parasites off it, which puts it somewhere between a lodger and a cleaner - one of the many small arrangements a reef runs on that nobody notices until they go looking.
- body entirely transparent apart from fine white and purple markings
- internal organs and gut visible through the shell
- always on a host - anemone, soft coral or urchin
- length up to 3 cm
