Came across this spiked Horseshoe crab at the shore near Carpark A. It was lying upside down and did not seem very bothered or in a hurry to right itself up. There were some other horseshoe crabs in an inverted position as well and perhaps this was a bevahioural trait for these crabs to be in an upturned position. (??)
Spiked Horseshoe crab @ Kranji 24Mar2011 from SgBeachBum on Vimeo.This particular crab had a forked tail with the extra spike on the anterior part of the main tail pointing upwards about a third of the way from the base of the tail. The cross-section of the main tail was also not symmetrical perhaps to accommodate the extra spike and the combined length of both the shorter main tail as well as the spike seemed to correspond proportionally to the single tails of the other Horseshoe crabs.
Siva suggested that the spike mutation could be due to pollution in the Johore Straits. We did not see any other unusual tails whilst on the shore.
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