Those who have been diving in Costa Rica, know that the waters around Playas del Coco and further out at Catalinas and Bats Islands are teeming with schools of tropical fish, rays, sharks and sea turtles. What many divers do not know is that we also have a great selection of macro diving. Amongst octopus, nudibranchs, spider crabs, frog fish and other little critters our favorites are the harlequin shrimp.
In this blog we dive into the interesting life of these colorful and very interesting little creatures.
The harlequin shrimp, is a saltwater shrimp species inhabiting coastal waters within the tropical regions of the Indian and Pacific Oceans. While traditionally regarded as the sole species in the Hymenocera genus, some classifications propose a division into two distinct species: H. picta, prevalent in the central and eastern Pacific, distinguished by deep pinkish-purple spots with a yellow edge, and H. elegans, found in the Indian Ocean and western Pacific, characterized by more brownish spots with a blue edge.
Harlequin Shrimp are renowned for their striking appearance, boasting vibrant colors and intricate patterns that make them stand out. These small crustaceans showcase a unique combination of bright purple, blue, and orange hues, arranged in a distinctive harlequin-like pattern across their bodies. This flamboyant coloration serves both aesthetic and functional purposes, aiding in camouflage and communication within their habitat.
Harlequin shrimp posing in front of his latest catch.
2. Ferocious and skilled Hunters
Despite their modest size – typically reaching around 5 centimeters in length – Harlequin Shrimp are highly skilled hunters.
Enter the intriguing world of the harlequin shrimp, where these masterful hunters showcase a unique culinary preference: starfish. Picture this underwater spectacle – a dynamic duo, typically consisting of one female and one male, skillfully flipping over a slow-moving starfish onto its back and then drag the victim to their usual hideout. With precision and finesse, they feast on the tube feet and soft tissues, gradually making their way to the central disk.
Armed with claws that can pierce even the toughest of starfish skins, these shrimp employ their feeding legs not only for navigation but also to assist in the intricate maneuvering required to access their prey's delectable portions. It's a dance of survival and sustenance beneath the waves.
In a remarkable display of adaptability, the starfish sometimes resorts to shedding the very arm that the shrimp has targeted, an evolutionary defense mechanism. While the starfish may attempt to regrow its lost limb, the wounds inflicted by the harlequin shrimp often leave it too compromised for a full recovery.
And there's more to the harlequin shrimp's menu ! These crustaceans may occasionally turn to sea urchins as an alternative source of sustenance. Sea urchins, like starfish, boast tube feet, making them a viable – albeit rare – option for the harlequin shrimp's culinary exploration. However, this shift in diet is more of an exception, occurring only when starfish are in short supply.
A pair of Harlequin shrimp posing in front of their latest catch.
3. Unusual Pair Bonding
Harlequin Shrimp exhibit a fascinating form of monogamous pair bonding, a behavior uncommon among crustaceans. Once a male and female form a pair, they remain together for a prolonged period, often for their entire lifespan. This unique partnership is not only a testament to the intricacies of marine life but also plays a vital role in their reproductive success. The pair collaborates not only in hunting but also in the intricate process of caring for their eggs.
4. Elaborate Courtship Rituals
The courtship rituals of Harlequin Shrimp are a spectacle in themselves. The male engages in elaborate displays of movements and tactile interactions to attract the female. Once a connection is established, the pair embarks on a joint exploration of their surroundings, reinforcing their bond. This intricate courtship not only ensures successful mating but also strengthens the cooperation necessary for their hunting endeavors.
5. Precarious Reproductive Strategy
Harlequin Shrimp employ a reproductive strategy that involves meticulous care for their eggs. After successful mating, the female carries the fertilized eggs, for two weeks beneath her abdomen until they hatch into miniature larvae. During this period, the male remains vigilant, guarding the female and their precious cargo. The symbiotic relationship between the pair extends to parenting duties, showcasing a level of cooperation and care rarely observed among crustaceans.
6. Vulnerability to Environmental Changes
While Harlequin Shrimp exhibit remarkable adaptations to their environment, they are not immune to the threats posed by environmental changes. Coral reef degradation, pollution, aquarium trade and rising sea temperatures can impact both their prey availability and the delicate balance of their ecosystems. Conservation efforts are crucial to preserving the habitats that sustain these colorful crustaceans and maintaining the biodiversity of the Eastern Pacific Ocean. Here in Costa Rica the Harlequin shrimp are rare but found throughout the year on some of our local dive sites. Coral reef degradation and pollution are luckily not common in our local waters but rising sea water temperatures might affect their reproduction rates.
7. Importance in Coral Reef Health
Harlequin Shrimp play a vital role in maintaining the ecological balance of coral reefs by controlling the population of crown-of-thorns starfish. These starfish, if left unchecked, can cause significant damage to coral formations by voraciously consuming the coral polyps. By keeping the population of crown-of-thorns starfish in check, Harlequin Shrimp contribute to the overall health and resilience of coral reefs, which are essential ecosystems for numerous marine species. Note that on the Costa Rican side of the Pacific we do not have any crown of thorn star fish.
8. Scientific Interest and Study
The unique behavior, vibrant appearance, and ecological significance of Harlequin Shrimp have captured the attention of marine scientists and researchers. Studying these fascinating creatures provides valuable insights into marine ecology, predator-prey relationships, and the delicate web of life within coral reef ecosystems. Ongoing research aims to uncover more about their reproductive biology, behavior, and responses to environmental changes, contributing to our broader understanding of marine biodiversity.
Harlequin shrimp are ferocious predators and skilled hunters.
9. Best dive sites to spot harlequin shrimp
Harlequin shrimp are found throughout the year on our local dive sites. The might be there for several weeks or months at the time if the conditions are favourable. Ask our expert dive guides to spot them for you as they are very hard to find !
10. Tips for Harlequin Shrimp Photography
Harlequin shrimp fall in the category of macro photography. If you want to get great shots you will need patience to capture a unique behavior. And you will need a good macro lense. My favorite setup is a sony fullframe camera with a 90mm lens and to get the details like eggs I even add a 10x diopter. To bring out the spectacular colors of the shrimp you will need one or two strobes or a video light. Please use any lighting devices with caution as they will harm the shrimp as they do not have eyelids. (Imagine how you would feel when someone is blasting their strobes in your face !) A good way to avoid harm to the animal is to take a few test shots of a rock or any other subject nearby to make sure you get the correct exposure. Shoot in RAW so you can make exposure and color adjustments in post processing.
Harlequin Shrimp, with their flamboyant colors, intricate behaviors, and crucial ecological role, stand out as a testament to the wonders of the Eastern Pacific Ocean. From their meticulous hunting techniques to their unusual pair bonding and intricate courtship rituals, these small crustaceans continue to captivate the imagination of marine enthusiasts and researchers alike. As we delve deeper into the mysteries of the ocean, the Harlequin Shrimp remains a symbol of the interconnectedness of marine life and the importance of preserving the delicate balance of our oceans.
If you want to dive with Harlequin Shrimp. Then contact us directly at:
Rich Coast Diving
Mrs. Céline Monfort
WhatsApp +506 8610 0914