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The Turtle that can't Hide its Head - Big-headed Turtle

Jun 2020
Author : Green Power

Turtles are often characterised by their ability to retract their heads and limbs in their protective shells; hence the term “head-hiding turtle” is frequently used to tease someone who is timid and dodge in face of difficulties. In reality, many turtles are unable to retract their heads; one such species native to Hong Kong is Big-headed Turtle (Platysternon megacephalum).

Big-headed Turtle is a freshwater turtle that lives both on land and in water. In Hong Kong, they are mostly found in the mountain streams in the New Territories. The species has a flat body and often hides among rock crevices and on stream bottoms. It cannot hide its head in its shell. Instead of being coy, Big-headed Turtle is quite aggressive! You have to watch out for its hooked beak and powerful bite! In Chinese, the species is sometimes named "flat-body turtle" and "hooked beak turtle" for the its features.

Literature shows that the Big-headed Turtle preys on insects, freshwater fish, hard-shell snails and freshwater crabs. However, local academics have in recent years examined the turtle's faeces and found it actually favours a "vegetarian" diet such as fruits and fallen leaves. Quite surprisingly, it was also discovered that digestion of the Machilus spp. fruits by the Big-headed Turtle would enhance seed germination success rate by 30%. The turtle turns out to be a guardian of flora!

Rarity as its fate

Big-headed Turtle is good at camouflage. The juvenile is orange-brown with a ridge running down the middle of its carapace, looking like a leaf vein from afar. As the turtle matures, the adult becomes dark brown, resembling a dry branch with the long scaly tail. The turtle usually conceals itself among the rocks and leaf debris in the river bottom. It avoids attention from predators by moving slowly or staying still for a long time.

The turtle, even with webbed toes, is actually a better climber than a swimmer. However, it can stay in water for a long time, in fact spending most of its life in the aquatic environment.

Big-headed Turtle reaches sexual maturity around the age of 8 to 13. Only two eggs are laid each time during reproduction. In addition, it has a restricted habitat and so the species is very rare. Unfortunately, its rarity made it valued, and the species is collected as a popular pet or for supposed medicinal value. For a long time, Big-headed Turtle has been over-hunted and smuggled from South East Asia to all over the world. The species is now listed as endangered on the IUCN Red List of Threatened Species and is protected in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Nonetheless, the threat of over-catching of the turtle remains in South East Asia including Hong Kong!

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Can you spot the Big-headed Turtle hiding among the plant debris in the water?
© Wenda Cheng
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The flat body of the Big-headed Turtle allows it to hide among rock crevices.
© Thomas Faunce
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A juvenile Big-headed Turtle
© Wenda Cheng
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Big-headed Turtle has a hooked beak.
© Thomas Faunce

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