Varuna litterata
Small, rarely-logged crab found clinging to floating weed off South Africa's Western Cape and KwaZulu-Natal coasts in 22 to 28 C water.
Small crab, around 4 cm across the shell, with a flattened, squarish body that lets it wedge into floating weed. Colouring runs mottled brown to olive-green, closely matching the sargassum or drift algae it clings to, and the legs are noticeably paddle-like for gripping and swimming through surface rafts rather than crawling reef rock. Look for it low in the water column near or on floating weed lines rather than on the bottom.
Divers find it clinging tight to strands of floating sargassum or drift algae, using its paddle-shaped legs to hang on rather than swim off when a raft is disturbed. It tends to stay low-key and camouflaged against the weed, only becoming obvious once you slow down and scan a weed line closely rather than swim past it. Because it's rare at most sites where it's been logged, most encounters are opportunistic finds during a slow, patient look through drifting weed rather than a planned sighting.
It spends much of its life riding rafts of floating sargassum and other drift algae out at sea, using the weed as both camouflage and transport rather than settling on fixed reef.
Sightings don't show a clear seasonal pattern, and the water-temperature range it's found in (roughly 22 to 28 C) spans much of the South African diving calendar, so treat this as a year-round, low-odds encounter rather than a seasonal target.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Every logged sighting so far comes from South Africa, with the Western Cape the strongest area and KwaZulu-Natal close behind. It is a species tied to floating sargassum and drift weed rather than fixed reef structure, so sightings cluster wherever weed rafts and inshore currents bring that habitat close to divers.
Mapping where Sargassum Crab is logged…
All confirmed sightings are from South Africa, particularly the Western Cape and KwaZulu-Natal coasts, wherever floating sargassum or drift weed collects near dive sites.
There's no detected season in the sighting data, and its temperature range (about 22 to 28 C) covers most of the South African diving year, so it's a year-round but uncommon find.
Look for a small, flat-bodied crab around 4 cm across, mottled brown or olive to match floating weed, with paddle-like legs for gripping drift algae rather than crawling on rock or coral.
They're small, typically around 4 cm across the shell, easy to overlook against a raft of floating sargassum weed.
It lives most of its life clinging to floating rafts of sargassum and drift algae out at sea, using the weed for both camouflage and as a ride on ocean currents rather than settling on the reef.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Sally Lightfoot Crab
2,422 sites
