Harlequin shrimp

The harlequin shrimp (Hymenocera picta) is a highly specialised crustacean that was officially described by Dana in 1852. You can recognise it instantly by its cream-white body adorned with striking blue, purple and pink spots. Some historical dive literature separated these animals based on regional colour variations. Scientists now recognise them as a single species across the Indo-Pacific. The World Register of Marine Species confirms this classification.

The animal has massive leaf-like claws known as chelipeds alongside complex paddle-like sensory antennae. They typically live in monogamous pairs within the deep crevices of coral structures or under tabular Acropora corals. These physical adaptations allow them to sense their prey from a distance. The broad claws help them flip a heavy sea star onto its back.

They occupy specific niches distinct from the open sand flats of the Celebes Sea. You will find them listed in the species inventories for the Tun Sakaran Marine Park and the undisturbed reefs of Tabawan Island within Darvel Bay. Harlequin shrimp are a lucky find during a dive week around Mabul and Kapalai. Their localised population relies entirely on the abundance of sea stars. Because they hide deep in the reef matrix rather than foraging out on the open muck they require dedicated searching.

Local guides intimately know their specific multi-generational resident crevices. Ask them to check known burrows during your dive. A notable scientific record confirms their presence further across the Pacific ecosystem. Their distribution in Sabah remains highly localised. Check the Kapalai house reef with your guide to see if a resident pair has established a burrow near the resort structures.

They are obligate predators of the Asteroidea class of sea stars. In the Indo-Pacific they famously hunt and immobilise much larger sea stars including the destructive Crown-of-Thorns starfish (Acanthaster planci) and Phataria species. They venture out only to flip and paralyse their prey. They drag amputated limbs back to their lair to feed slowly over several days.

When you watch them in the water they are cooperative and slow-moving subjects. They are fiercely protective of their food source. They rarely flee when a diver approaches quietly. Their strategy of keeping their prey alive ensures a fresh food supply over an extended period. This behaviour allows critters of Semporna to survive in isolated pockets where food might otherwise be scarce.

The challenge for your photograph is reaching them with light inside their crevice. The shrimps are usually found deep within tight dark reef crevices where ambient light cannot reach. Photographers rely heavily on snooting to capture them effectively. A cone attached to a strobe narrows the light beam to punch a single ray into the dark crevice. This highlights the shrimp against a stark black background.

You will need super-macro diopters like the SMC to capture the tiny serrations on their leaf-like chelipeds and their intricate sensory antennae. Because they are slow-moving you have time to adjust your settings and wait for the perfect pose. Be sure to check your strobe angles carefully to avoid casting harsh shadows inside the tight coral space. You can join underwater photography packages to practise these specific lighting techniques. Some photographers even try to locate them during night diving sessions when the reef transforms entirely.

Keep the animal's safety ahead of the photograph. These species rely exclusively on specific micro-habitats and delicate symbiotic relationships for survival. You must never move an animal out of its host or habitat for a cleaner photograph. Do not attempt to prod or unearth them from their coral ledge to force them into the open. A subject moved from its camouflage is exposed instantly to fatal predation.

The skill is in your buoyancy, lighting and patience as you photograph these well-hidden animals where they live. Approaching their burrows carefully ensures that future divers can enjoy the same encounter.

The coral rubble and massive coral structures of Darvel Bay face localised threats from marine litter. Studies have documented abandoned fishing nets and plastic bags impacting the reefs around Tabawan Island. Maintaining these environments is vital for the long-term survival of specialised predators that cannot adapt to degraded reef systems.

The harlequin shrimp relies entirely on a healthy population of sea stars to survive. Protecting the broader coral reef ecosystem helps sustain their food source. Sabah Parks manages the protected zones to limit destructive practices and allow these fragile benthic communities to thrive.

You can dive with harlequin shrimp by booking a trip that includes Tun Sakaran Marine Park or the emerging sites of Darvel Bay. Operators running macro and muck packages from the Semporna islands sometimes locate them on the local reefs around Mabul. The Mabul house reef occasionally hosts a resident pair if the conditions are right.

Ask your guide to check known crevices during your dives. You will maximise your chances by diving with professionals who map these active burrows season after season.

• Mantis shrimp
• Crocodilefish
• Critters of Semporna
• Diving in Kapalai
• Underwater Photography

Send the team your travel dates, the names of everyone coming and your certification levels. The team will come back to you with an itinerary that targets the best macro sites in the region.