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Phylum Arthropoda | Class Merostomata | Order Xiphosura > Family Limulidae
Mangrove horseshoe crab
Carcinoscorpius rotundicauda
Family Limulidae
updated Oct 2016
Where seen? This is the smaller of our horseshoe crabs and it is sometimes encountered in mudflats and mangroves and shores near them.

Features: Diameter to about 15cm. The circular shell is brownish. Identified by shorter spines on the side of the body, the tail is circular in cross-section near where it joins the body, without a groove on the underside and without spines on the upperside. The male's special legs for holding on to the female has two 'fingers'.

The underside is sometimes encrusted with Flat slipper snails (Crepidula walshi) and bryozoans.

Sometimes confused with the Coastal horseshoe crab (Tachypleus gigas). More on how to tell them apart.

Status and threats: This horseshoe crab is listed as 'Vulnerable' in the Red List of threatened animals of Singapore. According to the Singapore Red Data Book: "It is still relatively common in intact mangroves, and should survive as long as there are enough such habitats conserved."

Using its tail to flip over to the right side
Changi, Jun 05

Spines on the side of the body shorter.

Male's special legs for holding onto the female
has two 'fingers'.

Tail without a groove on the underside.

Tail near the body is circular in cross-section
and smooth on the upperside.

Pulau Sudong, Dec 09
Photo shared by Ivan Kwan on his flickr.

Juvenile horseshoe crab.
Kranji, Jun 08

Mangrove horseshoe crabs on Singapore shores

Photos of Mangrove horseshoe crabs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map



  • 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.
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