Xenocarcinus depressus
A rarely-logged whip coral crab found on Bali's reefs in warm water between 22.6 and 29.5°C, uncommon even where it occurs.
A small, flattened crab that hugs the branch of a whip coral or gorgonian rather than standing off it, which is the main giveaway underwater. Its body is depressed (flattened top to bottom) and mottled to match the coral host, breaking up its outline against the substrate. Legs are held close to the body rather than splayed, and it relies on stillness and camouflage rather than movement to avoid notice.
Divers find it parked motionless on a single whip coral or gorgonian branch, matched closely enough to the host's colour and texture that it takes a slow, deliberate scan to spot. It doesn't scuttle off when a torch or camera gets close, relying on camouflage rather than flight. Best found on guided macro or muck dives where the divemaster already knows which coral colonies to check.
Its flattened shape and colour-matched body are a permanent disguise fitted to one specific type of coral host, so finding the crab is really about finding and searching the right whip coral or gorgonian colony first.
Sighting data doesn't show a clear season, and with a comfortable range of 22.6 to 29.5°C it likely sits on its host coral year-round in Bali's tropical waters. Treat any time of year as fair game and focus effort on finding the right whip coral or gorgonian instead.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Currently logged from Bali, Indonesia, making it the one confirmed region for this species in diver observation data. Look for it on whip coral or gorgonian colonies on Bali's reef slopes, the kind of habitat this crab depends on for camouflage.
Mapping where Depressed Spider Crab is logged…
The only confirmed sightings logged so far are from Bali, Indonesia, where it turns up on whip coral and gorgonian colonies on the reef slope.
There's no detected seasonal pattern in sightings, and its warm-water niche of 22.6 to 29.5°C suggests it's present on Bali's reefs throughout the year.
Look for a small, flattened crab pressed tightly against a whip coral or gorgonian branch, coloured and textured to match its host. It stays still rather than moving, so a slow scan of coral colonies is the best way to spot one.
No, it's logged as uncommon even at the one site where divers have recorded it, so spotting one usually takes a guide who knows which coral colonies to check.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Sally Lightfoot Crab
2,422 sites
