The fiddler on the beach

If we take a quick look at the history of Mumbai we realise that the city today is formed by reclaiming and connecting the seven southern islands of erstwhile Mumbai viz Colaba Little Colaba Bombay Mazagaon Parel Worli and Mahim to the larger islands of Salsette and Trombay Islands in the north What most of us donrsquot realise is that Mumbai even today after massive reclamation is an island Sadly neither we nor our urban planners behave like islanders This lack of respect for our geography and the limitation of resources it imposes on the possibility of urban and industrial growth put our citys environment and biodiversity at a huge riskFiddler crabs are one of the most important detrivores creatures feeding on dead matter and perform the ecological role of bioturbulators or tillersOn hearing about the announcement of the coastal road and transharbour link towards Nhava Sheva my first reaction was ldquoWhat will happen to all the marine diversity found along the coast of Mumbairdquo Im a big fan of the coastline and sea as I think all islanders should be I have taken literally hundreds of students and adults for beach and mangrove walks right from Colaba in the south to Haji Ali Sewri Dadar Mahim Juhu Vikhroli Mulund Manori Gorai Uttan and further up till Vasai and Palghar too These sandy and rocky beaches harbour diverse creatures and the most lookedatrsquo or appreciated species tend to be the various shells conches and clams And sadly for me my favourite marine crabs are least focussed on I fell in love with marine crabs Brachyurans during my college days when I found a 1957 research publication booklet of the Department of Fisheries Bombay titled Marine Crabs of Bombay State written by Dr B F Chhapghar The booklet covered 81species of marine crabs found right from Okha now Gujarat down till Karwar now Karnataka The coloured plates and detailed sketches just drew me to that group of creatures And thatrsquos how I began crab watching They were intriguing and peculiar with their 10 stilted legs and pincers Ferrarilike foldable eyes deep burrows and rolled up sand balls But among all these crabs I found the fiddler crabs to be the most unusualFiddler crabs belong to the genus Uca Also called calling crabs they are semiterrestrial and unique in a way that the males possess one abnormally enlarged claw or chela pincher The males use this claw to wave and challenge other male crabs and to signal to potential females The size of the male crabrsquos claw and his vigorous wave indicates higher strength and virility mdash which is preferred by females It is not uncommon to see thousands of red creamish or yellow fiddler crabs armwrestling and combating other males during low tide in a mangrove mudflat Accidents are common and if a male loses his large claw the smaller claw grows in successive moults And thus we see fiddler crabs that are lefthanded and righthanded In females both the claws are small and of the same sizeThe name lsquofiddler crabrsquo doesnrsquot come from the wave or large claw It comes from the smaller clawrsquos unusual habit of picking up dead and decaying food under the protection of the bigger claw this looks like the crab is playing a fiddle Fiddler crabs are one of the most important detrivores creatures feeding on dead matter and perform the ecological role of bioturbulators or tillers They dig deep burrows throw the sand above the ground in the shape of balls They then take the food and dead material deep into the marshes which allows oxygenation cycling of soil and prevents anaerobic conditions which can kill the roots of mangrove plantsPredators such as gulls herons and jackals regularly feed on these fiddler crabs But a much bigger threat to their survival is the rapidly increasing oil leakages from the engines of fishing boats slicks caused by collisions of crude oil container ships and deep sea drilling and dredging for fossil fuels The oil not only covers the book gills of adults thus choking them but also coats and kills the eggs laid on the sea bed and the floating larvae of the crabs It will be an oversimplification to state that fiddler crabs are the lifeline of mangrove and coastal ecosystems So the next time if you chance upon fiddler crabs waving frantically at you remember that it doesnrsquot mean they are panicking and signalling for help In fact they may well be warning us humans that with the destruction of mangroves creeks coastlines and seas and disappearance of fiddler crabs we may be waving goodbye to our own race