Research
Boxer-Crab Research
A tiny crab carrying two living “pom-poms.”
From observation to nuclear-genome analysis.
A tiny crab carrying two living “pom-poms.”
From observation to nuclear-genome analysis.
Lybia tessellata is only one to two centimetres across. Its defining behaviour is carrying a small sea anemone in each claw, raising them like a pair of cheerleading pom-poms when threatened.
The animal is also called a pom-pom crab—an appealing appearance that conceals a remarkably complex relationship between two species.
Behind its charming appearance is a largely unexplored system of tool use, physical adaptation and interspecies dependence.
It uses sea anemones as weapons and tools, and can divide them to preserve a matched pair.
Repeatedly being held in a claw changes the anemone's colour and shape.
Whether both organisms benefit, or one is primarily being used by the other, has long remained unclear.
I first encountered the crab in a National Geographic feature. With fellow members of the Salesio Gakuin biology club, I then spent three years keeping, observing and experimenting with the species as the lead author of our paper.
The crab accepted an anemone whose natural range does not overlap its own, suggesting it may take whatever suitable anemone is locally available rather than relying on one fixed species.
Tissue sections showed that areas held most tightly contained fewer symbiotic algae. The evidence indicates that bleaching is driven primarily by continuous physical stress.
Starved crabs ate the anemones they carried; removed anemones showed little remaining regenerative capacity; and no food transfer was detected. Together, the experiments point to commensalism with little benefit for the anemone, or a relationship approaching predator and prey.
The nuclear genome of the genus Lybia is not yet registered in any public database; only mitochondrial-genome data are currently available (Gries et al. 2023).
Producing that sequence could create a genuinely new public dataset and bring us closer to the genetic basis of tool use and life with an anemone. Beyond this small crab, I hope the work can eventually contribute to pharmaceutical and life science.
A selection of interviews and reports about the research and the path behind it.