Tahukah anda - The Sex of Turtles

Several years ago, I went to Talang-talang Island, which has been constituted as a National Park under the jurisdiction of the Sarawak State Government. The most impressive thing about the island is the marine turtle conversation. A permit from the Forest Department is necessary for entry to the Park.

The location of Pulau Talang-Talang


Pulau Talang-talang Kecil


One important thing I’d learnt from the officer in-charge is concerning the sex determination of sea turtle. The majority of the world's turtles have environmental sex determination (ESD). This means the sex of sea turtle hatchlings is temperature dependent, with warmer temperatures increasing the number of female sea turtles at the expense of males.

There are two types of ESD:
Type 1
Warmer temperature (above 30°C, around 31 - 34°C) = female
Cooler temperature (below 28°C, around 22 - 27°C) = male
Temperature in between (29 – 30°C) = bisexual

Type 2
Warm and hot temperature = female
Temperature in between = male

Male Turtle


Female Turtle



Apart from the temperature, other factors that also contributed to the determination of turtle’s sex are hormones and enzymes. Beside the sea turtles, other reptiles that are ESD include lizards and crocodiles. For further reading, click ncbi and wikipedia.

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