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Marine Turtle Newsletter 32:2-3, © 1985

Twin Embryos in Unhatched Egg of Dermochelys Coriacea

Eng-Heng Chan
Universiti Pertanian Malaysia, Mengabang Telipot, Kuala Trengganu, Trengganu, Malaysia

This note reports the occurrence of twin embryos in an egg of the leatherback turtle, Dermochelys coriacea in Trengganu, Malaysia. The find was made on 15 October during the postmortem analysis of unhatched eggs taken from a hatchery described by Siow (1982). The eggs were buried in an enclosed area of the beach at a depth of about 70 cm of sand. Of the 28 eggs buried in one of the nests, 22, 2 and 1 hatchlings emerged after 57, 58 and 61 days of incubation, respectively, yielding a hatch rate of 89.3%. The nest was excavated 2 weeks after the last emergence and one moulded but intact egg was recovered. Upon opening, similar-sized twin embryos were found inside. Both were arrested at approximately the same stage of development, corresponding to stage 16 described by Yntema (1964) for Chelydra serpentina or approximately to stage 17 described by Crastz (1982) for Lepidochelys olivacea. The figure shows a 2X magnification of the fresh embryos taken before preservation in 8% neutral formalin.

The occurrence of twin embryos in D. coriacea appears uncommon. Deraniyagala (1930, 1932) found 5 eggs with twin embryos, some of which he figured and described in detail. Hughes et al. (1967) mentioned briefly finding a single egg with twin embryos. No studies on the natural incidence of twinning in D. coriacea have been undertaken. Information on twinning in other sea turtles is equally scanty. Glaesner (1924) described three sets of twins of Chelonia mydas, and Fujiwara (1964) noted eight cases of twinning in Caretta caretta.

Crastz, F. 1982. Embryological stages of the marine turtle Lepidochelys olivacea (Eschscholtz). Biol. Trop. 30:113-120.

Deraniyagala P.E.P. 1930. The Testudinata of Ceylon. Ceylon J. Sci. B. 16:43-88.

Deraniyagala, PEP 1932. Notes on the development of the leathery turtle, Dermochelys coriacea. Ceylon J. Sci. B. 17:73-102.

Fujiwara, M. 1964. Some cases of spontaneous twinning in the loggerhead turtle. ACTA Herp. Jap. 2:7-8. (In Japanese)

Glaesner, L. 1924. Uber drei Doppelbildungen von Chelone mydas. Zool. Anz. 60:185-194.