Energetic cost of behavioral thermoregulation in turtle embryos

The cost of behavioral thermoregulation is well recognized in the posthatching stage of ectothermic vertebrates. However, thermoregulatory behavior was discovered only recently in turtle embryos, and the cost of this interesting behavior remains unknown. We manipulated the intensity of thermoregulatory behavior in turtle embryos (Pelodiscus sinensis) and determined the hatching success, body mass, and righting response to assess the energetic cost associated with this behavior. Hatchlings from embryos that had experienced intensive behavioral thermoregulation were smaller and contained less energy than those from the control group, which indicates that behavioral thermoregulation by turtle embryos incurs energetic costs. Nonetheless, the smaller hatchings did not exhibit a lower hatching success or a slower righting response, suggesting that the cost incurred by behavioral thermoregulation is relatively low in turtle embryos.