This year a totally male-dominated crowd of hatchlings is expected to come out of the Olive Ridley eggs at their mass nesting site at Rushikulya rookery coast in Ganjam district of Odisha, predict zoologists and wild life experts.
“This would be due to the unique temperature-dependent sex determination or environmental sex determination found in reptiles like turtles,” said Bivash Pandav, scientist of Wildlife Institute of India (WII). Usually Olive Ridley eggs buried in the beach incubate because of warmth of the sand and hatch in 45 days. But this year incubation of eggs at this coast has taken longer time because of lowering of sand temperature due to tidal and other environmental factors. It is expected that these environmental changes would increase the incubation period to 60 days. Reptiles lack sex chromosomes so in their eggs sex determination occurs during a thermo-sensitive or temperature-sensitive period (TSP) that lasts for 7 to 15 days.
As per zoologists at cooler temperatures ranging between 22.5 and 27 degrees Celsius mostly male turtles are formed in turtle eggs and at warmer temperatures more than that only female turtles arise. Flow of tidal water on the beach during four major lunar tides, the sand of the coast cooled down during the temperature-sensitive period at Rushikulya rookery coast, said Mr Pandav. This lowering of temperature is also a major reason behind delay in incubation. It is interesting to note that unlike turtles this phenomenon of sex determination is reversed in lizards and snakes where lower temperature gives rise to female offsprings.
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