Scientists from Northeast Forestry University and the Zhejiang University School of Medicine collaborated to determine how the Chinese red-headed centipede detects light without the need of eyes or photoreceptors.
The group explains its experiments with the myriapods to determine how they detect sunlight in a report published in Proceedings of the National Academy of Sciences.
The venomous Chinese red-headed centipede has a long, black segmented body, yellow legs, and a big, eyeless head with long antennae and a mouth that may bite and inject venom into prey, predators, and humans who walk on them.
It is unclear from the existing literature whether the centipede avoids the sun to evade predators or to keep from overheating. Previous studies have demonstrated that the pencil-size bugs not only do not have eyes, but also lack the photoreceptors that would allow them to detect when sunlight is present.
The scientists ran various tests in which they placed specimens in transparent containers, some of which had black tape over them. How the centipedes behaved under different lighting conditions was then investigated. They also employed thermal cameras to monitor how sun exposure affected core body temperature. When exposed to sunlight, they observed that the antennae’s temperature increased rapidly. The readings revealed a 9 degrees Celsius rise in temperature in a matter of seconds.
Covering the centipedes’ curly red, segmented structures and re-testing the bugs to see how they react to unexpected flashes of light confirmed that the antennae were alerting the insects to sunlight. Due to the protection, the creatures were much less sensitive to light.
Antennae were examined further to determine their role as solar heat sensors, and the presence of thermal receptors termed BRTNaC1 ion channels was confirmed. The rise in temperature was what set them off.
Zhihao Yao et al, A thermal receptor for non-visual sunlight detection in myriapods, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2218948120