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Thursday 26 March 2015

Tale of a Tiny Sand Artist

In this post under GREEN HERITAGE we try to explore the life of an amazing Sand Artist...


Walking on a sandy beach, if you see a galaxy of designs made out of tiny sandy balls, don’t you get excited? Watch closely, you will see small burrows and tiny creatures popping out, looking around with watchful eyes. He is our sand artist- the Sand Bubbler Crab! This little beach dweller is an expert sand sculptor. The intricate unintentional designs are born out of simple necessity- he has to eat to survive!! Motivation is simple, but mechanics are not!! A lot of attention is given to animals in the categories of huge size, strong body, fast feet, but in ‘art category’ certainly the Sand Bubbler Crab is the Unsung Hero. 

Galaxy of designs created by the tiny sand artist!! 

Sand Bubbler Crab, though tiny in size, has special characters. He is humble but mighty- he uses his claws to dig burrows, sifts through sand, feeds on micro-nutrients and can toss sand balls away! He is a sober hard worker- never gives up, when the high tides wash away all the artistic work, he continues patiently to create more! He is very meticulous- cleans and maintains his burrow that protects him from enemies. He is an excellent manager of time- works in breakneck speed without wasting any time to feed as much as possible between tides! He is very practical and clever- throws the sand balls away from the burrow, pushes them away from the entrance of his burrow! He is heroic- fights single handed against the intruders of his territory! He is a stylish walker too!! 


Watch him creating sand balls while feeding !! 


Don’t you think this Hero deserves a bio sketch? Here it goes….. 


The shoreline of west coast of Karnataka harbours mainly three distinct habitats: sandy beaches, rocky shores and estuaries. The sandy bay of the coast is inhabited by innumerable creatures and Sandy Bubbler Crabs are the most interesting ones. Sand bubbler crabs are the small crustaceans, around 1 cm across the carapace, and they are characterised by the presence of 'gas windows' on the merus of the legs.These crabs dig burrows in sand and live. During low tide the crabs come out of their burrows and feed on the organic matter in the sand.The first sign of an emerging crab is a near circular to hole - the opening of the burrow - from which the crab checks several times to see if it is safe to emerge. Once satisfied, it re-enters the burrow and begins clearing it of sand. The crab uses its claws to scoop up small amounts of sand, eats up organic matter on each sand grain particle, rolls little balls of left over sand and tosses them out. These are the remarkable-looking reminders which help them from searching for food in the same sand twice.These tiny balls of sand measure approximately 2-3 mm. The feeding activity continues till the high tide comes.The sand bubblers quickly run into their burrows to protect themselves from high tides. During high tide the balls get washed away and the sea wave action replenishes the sand with micro nutrients. When the high tide subsides, crabs again come out for their next feast!

The crab is getting ready to toss the sand ball!!  

The Sand Bubbler Crabs belonging to the genera Scopimera and Dotilla (Family: Dotillidae) are widely seen in west coast of Karnataka. So far eight species of Dotilla and fifty species of Scopimera are known. The mating behaviour of these tiny creatures is amazing. They mate both on surface and inside burrows. Wandering males mate sequentially with resident females whereas the resident males chase the females, capture them and take them to burrows. The surface copulation has higher success rate than the underground copulation.

Two crabs in confrontation to protect their territories 


 Sea birds prey on sand bubblers. Though there are no direct threats from humans to the population of sand bubblers, we speculate that the increasing number of motorised fishing boats which harbour on the sandy bay in West Coast of Karnataka and the resulting oil spillage might create extensive habitat loss for the sand bubbler crabs over a period of time. Our observations at the Dhareshwara seashore are worth mentioning. A decade ago there were a very few traditional fishing boats. But at present there are nearly 50 mechanised fishing boats at Dhareshwara. The sandy bay at this beach is getting continuously polluted due to fishing boat's oil spillage, which eventually trigger habitat loss. The disturbed ecological niche will subsequently hamper the food chain as well as harmonious living of these tiny creatures.

Practical and clever crab has avoided blocking of the entrance!! Look at the free path!! 


Next time if you walk along the sandy beach, look for intricate patterns of balls. You can’t imagine in your dreams that a littered beach can be so beautiful!! Quickly take out your camera and capture the video of the action packed sequences of Sand Bubbler Crabs. Watch the video on your stressful day. It is really a stress buster!!

CAUTION!!- Crab’s eyes are watching you!! A tiny shade on sand will alert the crab and within a blink of an eye it runs and hides inside the burrows!!



6 comments:

  1. Very nice,very interesting to know about natural creature's routine. Actually I went to beaches so many times but I didn't tried to see such a wonderful things.Really want to say thank you so much to lakshmi madam and ravi sir for sharing with us.

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  2. Thank you Vivek. Next time u try to observe sand bubblers :)

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  3. Thats nice to know about sand bubbles and crab creating sand balls video..very good informations...All the best for the future work ..Ravi Hegde and Laksmi Murthi...(Y)

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  4. thank you. look forward to many more interesting posts :)

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  5. well done Ravi..great job..i am sure it was not easy to picturise them in action..keep going..

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  6. Loved this writeup very informative

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