Scientists find turtle embryos use antenna-like cells to sense sex-determining temperatures

A newly discovered antenna-like structure on turtle embryo cells may explain how the reptiles sense nest temperatures that decide their sex.

Researchers found tiny, hair-like extensions on cells in developing turtle embryos that resemble sensory antennae. These cilia appear to detect temperature shifts in the nest, triggering molecular signals that turn genes on or off. The finding, published in a recent study, offers the first direct evidence of how temperature controls sex determination in turtles without sex chromosomes.

Scientists have long known that turtle sex is temperature-dependent, a trait called temperature-dependent sex determination (TSD). In most turtle species, eggs incubated above 30°C (86°F) produce females, while cooler temperatures produce males. But the biological mechanism behind this switch has remained unclear. Earlier theories suggested temperature might alter hormone levels or enzyme activity, but no clear sensor had been identified. The new study points to the cilia as the missing link. These structures, found on many cell types, often act as environmental sensors in other animals. In turtles, they may be sensitive to subtle heat changes in the nest, activating or suppressing key genes involved in sex development.

The discovery could reshape conservation efforts for endangered turtle species threatened by climate change. Rising global temperatures are already skewing sex ratios in some populations, with too many females and not enough males. Understanding how embryos sense temperature could help scientists develop ways to stabilize sex ratios in the wild. Researchers next plan to test whether manipulating cilia function or nest conditions can influence sex outcomes in controlled settings. If successful, such insights might be applied to other reptiles with TSD, including some lizards and crocodilians.