Yellowline Arrow Crab

Stenorhynchus seticornis 

Maximum Size:

2.5 in (6 cm)


Around 5 years.

Typical depth:

10–130 ft (3–40 m)


Yellowline arrow crabs are small spider-like creatures with a triangular body and small purple claws. They are often found inside tube sponges, and among the tentacles of anemones and the spines of sea urchins. At night, they forage for algae, detritus, tube worms and bristleworms.


Grouper, puffers, triggerfish, wrasses and grunts.

Did you know?

Arrow crabs occasionally “decorate” their body spines with bits of algae and sponge. This decoration helps camouflage the crab from predators. At certain times of the year, female arrow crabs can be found carrying over 100 eggs in a flap beneath their body.