Arrow Crab (Stenorhynchus seticornis)

Nothing else on the reef moves quite like an arrow crab — a triangular head tapering to a point, legs so long and thin they look borrowed from a much bigger animal, the whole thing balanced on stilts. That build exists for hunting bristleworms after dark, picking them out of rockwork crevices other cleanup crew members can't reach, though it'll take a swipe at small ornamental shrimp if given the chance.

Care level: Easy · Temperament: Semi-aggressive to small inverts · Max size: ~5" leg span · Min tank: 20 gal · Reef safe: Yes (with caution) · Diet: Omnivore, scavenger