Hatching An Escape: Lizards Break From Eggs Early To Avoid Threats

Researchers have discovered that a species of lizard is capable of detecting threatening vibrations before being born and will hatch from their eggs prematurely to escape danger, launching into a sprint as they erupt from the egg.

The findings come after J. Sean Doody, a behavioral ecologist at the University of Tennessee, Knoxville was studying a population of delicate skinks (Lampropholis delicata) at a park in Sydney, Australia. Skinks lay their aspirin-sized eggs in rock crevices; the eggs usually incubate for four to eight weeks before hatching. But Doody and colleagues found a surprise when they were taking the eggs from the crevices to make measurements, according to a report from ScienceMag.org.

"They started hatching in our hands, at just a touch -- it shocked us," Doody said. "It turned into a real mess, they were just hatching everywhere."  

Shortly after, Doody launched a more systematic study of the phenomenon in a laboratory setting. He found that in the lab, eggs that were exposed to vibrations hatched 3.4 days earlier than eggs that were left alone. Doody reports the hatchlings made quick escapes in the field, sprinting for more than one-half meter in just a few seconds. "It's amazing," Doody said to Science Mag. "It can be hard to see because it happens so quick."

The early hatched skinks were reportedly much smaller and left more residual yok in their eggs, however, which suggests there a cost to hatching early.

The findings represent first quantitative evidence for induced early hatching in a reptile, according to the abstract of Doody's study, which was published in the March issue of Copeia.  

"Our results are unusual in demonstrating early hatching in a terrestrial animal with a simple life cycle, and likely extend predation-induced early hatching to reptiles. Early hatching may be widespread in oviparous vertebrates," the study reported.