A flattened, scallop-edged lobster that spends the day pressed into the roof of a cave.
A flattened lobster reaching about 20 cm, broad and shield-shaped, with no claws and with the second antennae modified into flat plates carried out in front like a pair of shovels. The margins of the shell and of those plates are cut into a row of rounded teeth, giving the whole outline a scalloped edge, and that edge is the character to go by. Colour is mottled grey, brown and purple, close to the rock it sits on. The other slipper lobsters in the region are straightforward to rule out: Scyllarides species are much thicker-bodied and heavier with smooth or bluntly rounded margins, and the small Scyllarus and Chelarctus are a fraction of the size. The species name is a historical relic and says nothing about where the animal lives; it is a tropical species with a circumtropical distribution.
Nocturnal. The day is spent inside caves, under ledges and in wrecks, very often upside down and pressed flat against the roof, where the flattened shape and the broken outline make it close to invisible. At night it moves out onto rubble and sand to feed on molluscs and carrion. Disturbed, it swims backwards in short hard bursts by flexing the abdomen, which is the usual way a diver loses one. On muck sites the records are mostly of animals sheltering in debris — inside pipes, tyres and broken wreckage rather than in reef caves.
Sightings are patchy and the record is thin. Part of that is the animal being cryptic and nocturnal, and part of it is fishing: slipper lobsters are taken for food across the region, and at shallow accessible depths near settlements the animals encountered tend to be few and small.
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.
