The Anemone Shrimp (Periclimenes longicarpus)

by B. N. Sullivan

Here is an interesting little critter: the Anemone Shrimp (Periclimenes longicarpus), which is endemic to the Red Sea and the Arabian Sea. This shrimp lives commensally among the tentacles of certain anemones. The anemones' tentacles have stinging cells, called nematocysts, which most potential predators of the shrimp cannot tolerate, thus the shrimp's choice of home affords it some protection from predation.

Like many other shrimps of its genus, this Anemone Shrimp makes its living as a cleaner, in a manner similar to the little cleaner fish that we discussed last year.

This nearly transparent shrimp is very tiny. Its body is barely 2 cm (3/4 inch) long from its rostrum (i.e., snout) to the end of its tail. Its body has a pale lavender tinge to it, and its appendages and tail are marked with violet spots, and edged in white.

We think this shrimp is quite good-looking. It is a great subject for macro photography, although its very small size and transparency can make it difficult to find, unless you know where to look. We have seen them most often in two species of anemone: the Bubble Tip Anemone (Entamacea quadricolor), and the Sun Anemone (Gyrostoma helianthus). The trick is to learn to identify these anemone species so you can spot them, then look closely to see if there are any Anemone Shrimps among the tentacles.

In the Red Sea, these Anemone Shrimp very often share their quarters with the Two-bar Anemonefish (Amphiprion bicinctus) -- AKA Red Sea Clownfish. The photo at left shows a juvenile Two-bar Anemonefish as well as an Anemone Shrimp. Note that the baby fish is even smaller than the shrimp!

For those interested in taxonomy, this Anemone Shrimp belongs to the family Palaemonidae. The family is relatively large, and is divided into two sub-families. The Periclimenes genus, of which this shrimp is a member, belongs to the sub-family Pontoniinae, characterized by their short, flattened rostrums. Most of the shrimps in this taxonomic group are known to live commensally with other invertebrates.

I photographed the two individuals on this page in the Red Sea, at a place on the coast of Tiran Island called Khush Khasha. Both were living in the same anemone. You can click on either of the photos for a larger view.