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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > prawns and shrimps >
Family Palaemonidae
Machine gun coral shrimp
Coralliocaris graminea
Family Palaemonidae
updated Jan 2020
Where seen? This fat little green shrimp is sometimes living among branching corals such as Acropora corals (Acropora sp.) and Montipora corals (Montipora sp.). It is usually well hidden and hard to spot and photograph.

Features: About 1cm long. Body is short and fat, with a bent back. Large eyes wide apart. Usually dark green with fine stripes of white, black, red and blue.

Double snap: It has a pair of huge flattened pincers that can be larger than its body. Like the snapping shrimps (Family Alpheidae), the pincer has an enlarged tooth and a special catch. When the catch is released, the tooth makes a loud snapping sound. Unlike the snapping shrimp which only has one such 'snapping' pincer, the Machine gun shrimp has two such pincers, hence its common name. But the 'snaps' of the Machine gun shrimp is not as powerful as those of the snapping shrimps.

The shrimps probably use their snapping pincers to protect their home from animals that might damage the coral. They are not believed to eat their host and simply use the coral as shelter.

Usually, a pair is seen in a single coral colony.

Cyrene Reef, Aug 10

Pulau Hantu, Jan 11

Machine gun coral shrimps on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Tanah Merah, Jun 10
Photo shared by James Koh on his blog.

Tanah Merah, May 13
Photo shared by Loh Kok Sheng on his blog.

Tanah Merah, Jun 11
Photo shared by Loh Kok Sheng on his blog.

Labrador, Sep 19
Photo shared by Loh Kok Sheng on facebook.

A juvenile.
Sentosa Serapong, May 12
Photo shared by Loh Kok Sheng on his blog.

Sentosa Serapong, May 12
Photo shared by Marcus Ng on flickr.

Kusu Island, Jun 15
Photo shared by Marcus Ng and flickr.

Kusu Island, Jun 10
Photo shared by Loh Kok Sheng on his blog.

Kusu Island, Jun 21
Photo shared by James Koh on flickr.

Pulau Senang, Jun 10
Photo shared by Marcus Ng on flickr.

Terumbu Semakau, Nov 12
Photo shared by Loh Kok Sheng on flickr.



  • Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach. Division of Biology, School of Science, Nanyang Technological University & Department of Zoology, the National University of Singapore. 160 pp.
  • Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • Jones Diana S. and Gary J. Morgan, 2002. A Field Guide to Crustaceans of Australian Waters. Reed New Holland. 224 pp.
  • Humann, Paul and Ned Deloach. 2010. Reef Creature Identification: Tropical Pacific New World Publications. 497pp.
  • Kuiter, Rudie H and Helmut Debelius. 2009. World Atlas of Marine Fauna. IKAN-Unterwasserachiv. 723pp.
  • Debelius, Helmut, 2001. Crustacea Guide of the World: Atlantic Ocean, Indian Ocean, Pacific Ocean IKAN-Unterwasserachiv, Frankfurt. 321 pp.
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