First Report of Twinning in the Hawksbill Sea Turtle (Eretmochelys imbricata) from Khram Island, Chonburi Province, Thailand

Abstract

Twinning in reptiles and especially in the sea turtle, occurs rarely. During an investigation (May – August, 2011) of the nesting monitoring program on Khram Island, Chonburi, where an important nesting site in Thailand is located, we found that the number of female turtles has decreased. Unexpectedly, twinning in hawksbill turtle embryos has also been reported. This is the first discovery of such a phenomenon in the Gulf of Thailand. An un-hatched egg, with two fully developed embryos has been found. The embryos shared one yolk sac and differed substantially in size. The larger one has a carapace deformity with a 31.5 mm curved carapace width and a 22.5 mm length, while the smaller embryo has a normal carapace with a 16.5 mm width and a 18.5 mm length. However, the causes of twinning in sea turtles are still not well understood. Low temperature has been suggested as a possible factor. Other environmental or genetic factors could also be involved. For further studies, the pattern of the twins' and parental DNA should be investigated.