Thursday, January 14, 2016

Temperature decides the sex of Sea Turtle

Temperature decides the sex of Sea Turtle

Do you know the difference between Turtles and Tortoises? Both are reptiles. Turtles live in the water some or nearly all of the time and the Tortoises dwell on land. 

Sea turtles beck is lighter as compare to tortoises. Moreover, its front and back legs are adapted to swim in water and with help of them it can swim at the speed of 55 km/hr. Due to more holding capacity of oxygen in blood, it can swim continuously for 3 hrs in one breathe. It is believed that it takes 30 years to gain adult stage and several decades to reach sexual maturity. It can live up to 100 years. Normally sea turtle feeds on algae and sea grass.

The mature turtles migrate, sometimes for thousands of miles, to reach breeding sites. Male and female turtles mate in the water, and the males return to deep sea to feed. For several weeks, female sea turtles alternate between mating in the water and laying their eggs on land. Before laying her eggs, a female turtle will dig a hole in the sand with her hind flippers. She covers it with sand and 
returns to the ocean. About two months pass for the eggs to incubate under the sand. The eggs hatch generally at night to avoid predation and the hatchlings crawl to the sea. They then swim out to sea to begin their own cycle of maturing and reproducing. Sea turtles can continue this cycle until they are 80 years old. 

Globally, there are seven species of sea turtle observed in the Oceans. However, four species of turtle believed to be observed in the state of Gujarat (Gulf of Kutch), only the Olive ridley (Lepidochelys olivacea) and Green turtle (Chelonia mydas) are reported to breed while Leatherback (Dermochelys coriacea) and Hawksbill (Eretmochelys imbricate) are seen occasionally.

Sea turtle, even at the diminished population levels, can play an important role in Ocean ecosystems by maintaining healthy sea grass beds and coral reefs. This helps in providing key habitat for other marine animals, thus helping to balance marine food webs and facilitating 
nutrient cycling from water to land.

Over a time, nest predation by animals and consumption of eggs by local people are common threat to sea turtle. Incidental catch in fishing gear, marine pollution, unregulated development of marine areas and disease are reasons for decline in 
sea turtle population. Climate change and Oil spill pollution may also cause a threat to sea turtles.

To conserve these endangered creatures such as green sea turtle and olive ridley turtle the artificial breeding activity (hatching of eggs and subsequent release of young ones in natural environment) has been undertaken by the Marine National Park at Okhamadhi and Madhavpur beach area (Gujarat), the nesting sites of the turtles. The success is encouraging (75%) more than 15,000 hatching of green sea turtle and olive ridley turtle have been released in the sea.

It is interesting to know that the temperature of the earth where the eggs are laid decide the sex of the hatchling. If the temperature is high, it becomes female turtle and if it is low, it becomes male turtle. Turtles have temperature dependent sex determination.

In humans the sex is determined by the pair of sex chromosomes (male: XY, female: XX).  XY decides the sex of the offspring. But many a times it is noticed that some females deliver more baby boys and some deliver more baby girls. Hormonal and pH conditions within the female reproductive tract vary with time, and this affects the sex ratio of the sperm that reach the egg. In the era of molecular biology of sex determination, the inter play of pro males, pro females, anti males, anti females genes make the system complicated. 

Taking clue from the turtles, the internal temperature of ovary may be one of the reasons to be checked for the male Y chromosome to achieve or fail in conception. Ayurveda treatment (what to eat and what not to eat) and medicines for getting male child is mostly working on cooling off the internal system of the female. God knows, but turtle theory of temperature deciding the sex may be useful for the Asians who are blindly exploding the population in want of a male child. 

Forget that chromosome jargon, if you haven't seen the Sea Turtles, one of the wonders of Nature, don't wait much, pick up transport and drive down to Okhamedhi and Madhavpur on Gujarat Sea Coast. There are bright chances to see Dolphins too. Some big adults turtles will swim in the sea waves to make your trip joyful.

Punamchand
14 January 2016

NB: Madhavpur is also known for its historical importance as Lord Krishna  and Rukmani wedded in Madhavpur.

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