What Divers Should Know About Harlequin Shrimp

The harlequin shrimp, Hymenocera picta, is a truly distinct sight on Indo-Pacific coral reefs. Reaching a modest 5 cm in length, these small crustaceans are easily identified by their cream or white bodies adorned with vibrant spots. Spot coloration varies geographically; divers in the central and east Pacific might observe deep pinkish-purple spots with yellow edges, while those in the Indian Ocean and west Pacific often encounter individuals with brownish spots bordered by blue. Hawaiian specimens showcase a mix of purple and red. Their flattened, almost petal-like claws and sensory antennules give them a unique, almost ethereal appearance as they move slowly across the reef.

Often encountered in male-female pairs, harlequin shrimp are specialists, feeding exclusively on starfish. They are remarkably skilled predators, capable of flipping over a starfish and systematically consuming its tube feet and soft tissues. This specialized diet includes the formidable crown-of-thorns starfish, which they effectively subdue within a few days. These beautiful shrimp are typically found below the intertidal zone in warmer reef waters, though their rarity is increasing due to changing coral reef conditions. Their deliberate, wave-like movement and constant, almost hypnotic motion of their large claws make them a captivating subject for patient divers to observe.