Harlequin Shrimp – Thailand’s Cruel Crustacean

Harlequin Shrimp – Thailand’s Cruel Crustacean

Harlequin Shrimp – Stunning Critter With A Touch of Macabre

Sure harlequin shrimp are incredibly beautiful, a rare sight that excites guides as much as guests. However they do have a very macabre way of filling their little shrimpy bellies. They are reasonably frequent finds on our Phuket dive tours and have been spotted from the Racha’s to Phi Phi. Harlequin shrimp are very difficult to find, it’s usually just sheer luck but occasionally a maimed starfish or two can point you in the right direction.

The Basics

Officially there’s only one species (Hymenocera picta) that has a range across the tropical Indian and Pacific oceans. At one stage there was thought to be two different species, our Indian Ocean locals given the scientific name Hymenocera elegans. Researchers, in an effort to justify funding and blag some free scuba diving are still confusing matters. It’s still hard to find a definitive answer so for now we’ll stick with picta

Plenty of research, observation and of course dissecting still remains to be done before a conclusion can be made. The dissecting may seem a little harsh but as you’ll find out later it’s just a taste of their own medicine.

Harlequin shrimp form a monogamous pair and can live up to seven years but that’s rare in the wild. Pufferfish, mantis shrimps and large crabs can all stop harlequin shrimp from living a full life.

Females are generally larger than males and can grow to 5cm in length without the interruption of the above predators. The only definite way of telling male from female is to flip them over, only the female has markings underneath the abdomen. We obviously don’t recommend that you do that.

the female is most likely the larger animal on the left

the female is most likely the larger animal on the left

A Big Bluff?

The outrageous colours that make them so attractive to macro photographers, suggest they are toxic. The predominant prey is starfish which certainly carry toxins and so the shrimp could possibly absorb some. As of yet, no toxins have been found to be present so the garish outfit could just be a big bluff. A ballsy move indeed

The Dark Side

So this is where our cute, colourful little shrimp turns into a bloodthirsty butcher. They feed almost exclusively on starfish but occasionally urchins get the slice and dice treatment. They have incredibly sensitive antennae that very efficiently locate starfish. Once found they begin a team effort to subdue their prey.

harlequin shrimp feeding on the severed leg of a large starfish

harlequin shrimp feeding on the severed leg of a large starfish

One of the pair will nip of the gripping feet of the starfish while the other turns it over to render it helpless. On smaller starfish, the entire animal can be taken back to the lair to be slowly eaten alive over a period of weeks. Harlequin shrimp have even been observed to feed their meal to keep it alive and fresh.

With larger starfish that are too heavy to carry, they will cut off one the limbs and take it back to their hole in the reef. Any starfish is fair game for these savage shrimp even the coral crunching crown of thorns is on the menu. So if you’re seeing a fair number of starfish with missing limbs in a small area, there’s probably a pair of harlequin shrimp in the vicinity.

If you want to get a photo of this magnificent crustacean the get in touch with Local Dive Thailand. If there are any around, our fantastic guides will be sure to know about it.

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By Justin Hartrey

I've been enjoying the incredible marine life in our oceans for over 25 years. 13 years ago I became a PADI professional, hoping to introduce as many people as possible to the incredible beauty of the seas.

Having been fortunate enough to dive all over south east and especially Thailand, I enjoy sharing my experience and passion on this blog.

Posted in Rare & Peculiar Critters on .

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