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Phylum Arthropoda | Class Merostomata | Order Xiphosura > Family Limulidae
Coastal horseshoe crab
Tachypleus gigas
Family Limulidae
updated Nov 2019
Where seen? This is our larger horseshoe crab and it is sometimes encountered on some of our shores, on sandy shores near reefs and seagrass meadows. They are often seen in pairs, with the smaller male on top of the larger female. Elsewhere it is found in mangroves, sandy beaches and muddy bottoms.

Features: Diameter to about 25cm. The circular shell is greyish sometimes brown. Identified by longer spines on the side of the body, the tail is triangular in cross-section near where it joins the body, with a groove on the underside and with a serrated edge on the upperside. The male's special legs for holding on to the female has one 'finger'.

Sometimes confused with the Mangrove horseshoe crab (Carcinoscorpius rotundicauda). More on how to tell them apart.

Often seen in a pair.
Sentosa, Jun 06

Underside with encrusting animals.
Changi, Apr 09

Spines on the side of the body longer.

Male's special legs for holding
onto the female has one 'finger'.

Tail with a groove on the underside
near the body.

Tail near the body is triangular in cross-section
with small spines on the upperside.
Status and threats: The Coastal horseshoe crab is listed as 'Endangered' on the Red List of threatened animals of Singapore. It is mainly threatened by habitat loss.

According to the Singapore Red Data Book: "In the last two decades, many good natural shorelines have been developed or 'improved' through a variety of 'beach improvement' schemes, reclamation and other developments, so much so that the Coastal horseshoe crab has become less common and the species should be regarded as endangered in the Singapore context."

Coastal horseshoe crabs on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Changi, Oct 20
Photo shared by Marcus Ng on facebook.

A male, with its modified first claws.


Beting Bronok, Jun 18
Photo shared by Loh Kok Sheng on facebook.

Tuas, Jun 15
Photo shared by Loh Kok Sheng on facebook.

Tanah Merah, Jun 09
Photo shared by James Koh on his blog.


Changi, Mar 17
Photo shared by Marcus Ng on facebook.

Coney Island, Apr 19
Photo shared by Richard Kuah on facebook.


Berlayar Creek, Oct 15
Photo shared by Marcus Ng on facebook.

Berlayar Creek, Jan 17
Photo shared by Marcus Ng on flickr.


Sentosa Tg. Rimau, Jun 17
Photo shared by Abel Yeo on facebook.


Pulau Hantu, Jan 11
Photo shared by Russel Low on his blog.

Pulau Semakau South, Jul 15
Photo shared by Jianlin Liu on facebook.


Pulau Semakau North, Aug 16
Photo shared by Russel Low on facebook.

Pulau Semakau, Oct 18
Photo shared by Marcus Ng and flickr.

Links

References

  • 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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