Scientists have documented the first record of triplet embryos in wild sea turtles.
Polyembryony – when multiple embryos develop from a single fertilised egg – is extremely rare in reptiles, and even more so in turtles.
Most reported cases of polyembryony in turtles involve twin embryos, and the majority of these are documented in captive freshwater turtles. There are, however, several cases of twin embryos in wild sea turtle populations, including the olive ridley turtle, leatherback turtle, loggerhead turtle, hawksbill turtle and green turtle. The rarity of twin embryos in sea turtles makes the discovery of triplet embryos particularly noteworthy.
The finding “represents one of only two documented cases of triplets in chelonians [turtles, tortoises, and terrapins], and the first recorded in a wild sea turtle nest,” say the researchers, who published their findings in Ecology and Evolution. The only other record of triplet embryos in sea turtles was observed in managed conditions.
The egg documented in the recent study came from a green turtle nest on the Guanahacabibes Peninsula in Cuba. It was found unhatched during a long-term sea turtle monitoring programme by staff from the University of Havana and Guanahacabibes National Park, alongside trained volunteers.
Necropsy of the unhatched egg revealed that it contained three embryos attached to a single continuous yolk mass. Each embryo had its own distinct body structure and vascular network.
Reptile triplets like this have been reported (albeit rarely) in wild lizards, snakes and crocodilians, but not previously in wild sea turtles. “This new observation extends the known spectrum of naturally occurring polyembryony in reptiles and provides a unique opportunity to examine the developmental processes underlying this phenomenon,” add the authors.
Find out more about the study, published in Ecology and Evolution.
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Top image: wild sea turtle triplet embryos. Credit: Adapted from Julia Azanza-Ricardo et al., Ecology and Evolution 2026 | CC BY 4.0
