Lybia tessellata
Spot the Carrying Crab in Bali, Lombok and the Maluku Islands, where it holds tiny anemones in each claw. Warm Indo-Pacific reefs, 27-29 °C.
Look for a small, rounded crab that holds a tiny anemone in each front claw, like a boxer with living pompoms. The carapace (upper shell) displays a tessellated (tile-like) mosaic of reddish-brown and cream. Those permanently clutched anemones are the single most reliable field mark underwater, shared by no other common reef crab. The legs are banded in matching pale and dark tones, blending with rubble and low coral.
Carrying crabs are almost always found slowly picking their way across rubble, coral rubble slopes, or low-profile reef at night or in sheltered shaded spots, using their anemone-bearing claws to deter predators rather than to feed. When approached by a diver they tend to freeze or tuck into a crevice rather than flee, making them easy to observe if you move slowly. Because they are small and cryptic, most encounters are fleeting glimpses under torchlight or by a patient diver scanning rubble carefully.
The anemones held in each claw are not decoration; the crab uses them actively as defensive weapons, thrusting the stinging tentacles toward threats. In return, the anemones gain mobility and access to food scraps from the crab's feeding, a mutualistic relationship that biologists consider one of the most specialised tool-use behaviours known in crustaceans.
No clear seasonal pattern emerges from the available data, so sightings appear possible year-round. The species is consistently associated with warm tropical reef temperatures of around 27 to 29 °C, meaning any visit to its Indo-Pacific range during normal dive conditions is a reasonable opportunity.
Most sightings come from Indonesia, particularly the reefs around Bali, Lombok and the islands of Maluku and Papua. Taiwan is the second-strongest location, with Liuqiu Island and Lanyu (Orchid Island) accounting for most records there. Smaller numbers have been logged in Saipan in the Northern Mariana Islands and on Luzon in the Philippines.
Mapping where Carrying Crab is logged…
Indonesia is by far the top destination, especially the reefs of Bali, Lombok and the Maluku and Papua regions. Taiwan's Liuqiu Island and Lanyu are also well-represented in diver records. Smaller numbers have been observed in Saipan and the northern Philippines.
Available sighting data does not point to a particular season, so encounters are possible throughout the year. The species favours warm tropical reefs around 27 to 29 °C, which are stable year-round across its core Indonesian and Taiwanese range.
The giveaway is immediate: it is the only common reef crab that holds a living anemone in each front claw at all times. The carapace has a distinctive reddish-brown and cream mosaic pattern. The whole animal is small and easy to overlook unless you are scanning rubble slowly, ideally with a torch.
Carrying crabs are very small crustaceans, typically only a centimetre or two across the carapace. Their small size, combined with cryptic colouring, is the main reason they are rated rare at most sites even where they are present.
It uses the stinging tentacles of the anemones as a defence against predators, actively brandishing them when threatened. The anemones benefit too, gaining transport and access to food particles. This mutualism is one of the most well-documented examples of tool use in crabs.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
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