Peering into a crevice, you stumble upon what looks to be a beautiful underwater flower. Taking a closer look, you notice it has legs and its holding a starfish captive. What is this unique little creature? It’s a Harlequin shrimp, also known as Hymenocera picta. These flamboyant shrimp can be found in tropical waters of the Pacific and Indian Oceans. They are brightly colored, ornate crustaceans. In the animal kingdom, this kind of appearance usually means, “stay away, I am deadly”, but this is not the case with Harlequin Shrimp. Although some believe they may absorb toxins from their prey, it has not be scientifically proven. The bright spots on a Harlequin shrimp are a sort of “false advertisement”. Whether they are toxic or not, their bold body pattern serves to deter predation, allowing them to hunt out in the open along the reef.
Harlequin shrimp are fierce predators. With a taste for starfish, these inch-long shrimp take on prey hundreds of times their size. Although they prefer smaller, more sedentary starfish, not even the Crown-of-thorns is safe from the grasps of a Harlequin shrimp. They sense prey with their flattened antennules: flipping it upside down, immobilizing and consuming its fleshy undersides while its still alive. The lucky starfish get away by shedding the arm that has been attacked. Once caught, a starfish will provide food for days, even weeks. The shrimp have even been seen feeding the starfish to keep it alive while they dine on it.
Usually found in two, the pair consists of a male and a female. This is because once they find a mate they form a monogamous, territorial bond for life. They hunt, feed, and guard their home together. The slightly larger female produces anywhere between 100 and 5,000 eggs per season. She tends to and cleans them until the day they hatch. These eggs are almost always found in mating pairs whom can be found in the same area along a reef for months at a time, if not years.
Here in Manuel Antonio, these shrimp are considered local residents. They can be found at numerous dive sites but are only occasionally seen by divers. Many times they are found only because the starfish they are feeding on gets noticed first. Hiding in crevices amongst the rocks, you have to be lucky to catch a glimpse of them. Usually unfazed by divers’ presence, they make great subjects for photographers.
Harlequin shrimp are one of the most interesting critters found here in Manuel Antonio. Whether a seasoned professional or a first time diver, no one can deny they excitement they feel when they see the slow, methodical dance of the Harlequin shrimp as they wave their paddle-like claws in a continuous circular motion as if trying to hypnotize you. They are truly one of the most visually stunning creatures found on the reef.