Flora index
Fauna index
guide to the mangroves of singapore
Horseshoe crabs
Peter K L Ng and N Sivasothi (editors)
Mangrove horseshoe crab
Carcinoscorpius rotundicauda
Family Limulidae

up to 40 cm in length (plus tail)

The horseshoe crab is a survivor unlike other mangrove animal alive today. It is what biologists call a 'living fossil' an organism which has remained basically unchanged for millions of years! In fact, fossils of horseshoe crabs over 400 million years old look almost identical to the species alive today. Slow and steady nonetheless, they have withstood the ultimate challenge Mother Nature has thrown at them - the test of time!

Mangrove horseshoe crabs are basically scavengers, but they also feed on bivalves. They are found throughout Southeast Asia. The telson or tail is used to right itself up when overturned and not as a weapon as some believe!

Their large eggs, which hatch into miniature versions of the adults, are laid in the upper parts of the mangroves. Males (usually much smaller than females), cling on to and follow their potential mates around for long periods before egg-laying. Not surprisingly, some locals identify this crab with matrimonial fidelity.
close-up of mating pair
Mating pair of Mangrove
horseshoe crabs
(the male is the smaller animal)

close-up of larva
Larva of horshoe crab

close-up of underside
Book gills on underside

close-up of crab righting itself with its tail
The sabre-like telson of
the horseshoe crab is used
to right itself up
The eggs of these crabs are eaten in some areas, with locals cutting open the body and eating the unlaid eggs directly after cooking. There have been some reports, however, of the crabs being toxic. The blood of the crab is important in the biomedical world as a purified version can help detect baterial toxins, important in disease detection as well as ensuring the cleanliness of equipment.

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What is mangrove?

The Ecosystem


Indirect uses
Potential uses

About Mangroves
in Singapore

Mangroves to visit
From "A Guide to Mangroves of Singapore", Peter K. L. Ng and N. Sivasothi (editors)
Volume 1: The Ecosystem and Plant Diversity and Volume 2: Animal Diversity
Authors: Kelvin K. P. Lim, Dennis H. Murphy, T. Morgany, N. Sivasothi, Peter K. L. Ng,
B. C. Soong, Hugh T. W. Tan, K. S. Tan & T. K. Tan
BP Guide to Nature Series published by the Singapore Science Centre, sponsored by British Petroleum
2001 Raffles Museum of Biodiversity Research, The National University of Singapore & The Singapore Science Centre