Kranji Mudbath

06Jul08

The setting for today’s adventure involves a significant amount of mud and thus, however one would like to look at it, cannot quite be described as glamorous. Things are perhaps justified by the subject, which is undeniably interesting: the horseshoe crab, living fossil, humble scavenger, and -  to lovingly bastardise Hughes’ poetry -  god of mud. This is horseshoe habitat, at low tide. Horseshoe crabs trawl the bottom of mudflats and mangrove swamps as they forage for worms, clams, dead animals and other such delicacies…

 

 

Research involves trudging and glomping through the thick, deep mud to collect crabs. They are then brought ashore briefly to be measured and recorded, and subsequently returned. There is also the opportunity to chance, not too rarely, upon horseshoe couples doing their horseshoe thing. No photos of this unfortunately, as was collecting crabs (and at one point retrieving hat, which had unceremoniously fallen into the sludge).

 

 

Two species of horseshoe crab can be found in Singapore, the smaller and more common of which is pictured here. The other species is rarely recorded, and considered vulnerable. Numbers are believed to have declined in recent decades, although more data is needed – information which is being contributed by the Horseshoe Crab Rescue and Research program. The program is run by Dr Hsu and, for those who are interested, offers informal certification for budding Rescuers and Researchers.

 

 

(Above: note tiny crablets!) Horseshoe crabs are not true crabs, and are of conservation value for a number of reasons. Their blood is blue, as copper (rather than iron, the element common to vertebrates) is what helps transport oxygen in their system. Horseshoe crab blood also possesses a substance that is sensitive to, and can hence help detect, bacteria; this is already being used in the medical field. With simple light sensors rather than complex eyes, horseshoe crabs have also contributed to current knowledge on eyesight.

 

 

Just when you thought invertebrates couldn’t be cute…

 

 

Pails of crabs after measuring and recording, ready for release. In previous months horseshoe crabs have had to be rescued from the nets of fishermen. Trapped in the nets, they cannot escape when the tide recedes.

 

 

Today’s session was conducted in conjunction with the nature society’s Fun with Nature program, which offers educational hands-on lessons for kids. ‘I hate mud,’ one hapless little person, caked all over with the stuff, proclaimed vehemently on the way to the hose. Collecting horseshoe crabs is hot, laborious, dirty work. But it is also gloriously addictive, and I’d like to come back.

 

 

References:
See Sungei Buloh page on horseshoe crabs here.

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