Vivien Kent/Alamy; (inset) Discott/Creative Commons

ScienceShot: Termites Do the Wave

Like guards on duty, soldier termites stand watch at the center of their mound to protect the nest. Long passageways extend outwards from this central nest to foraging sites where worker termites collect food for the colony. If an aardvark or other predator creates a hole in the mound, these commandoes repeatedly ram their heads into the ground to create drumming alarms that alert worker termites in the corridors to quickly retreat to the nest. This vibrational communication has been observed in several species of termites, but scientists wanted to see how these alarm signals were communicated across mounds with a diameter up to 30 meters in length. So researchers opened up the mounds of Macrotermes natalensis termites in a South African mountain range and filmed the soldiers’ drumming signals using a high-speed video camera. They also implanted devices in the ground at various locations to measure the vibrational speed of the head-banging. M. natalensis termites pound their heads into the ground at a speed of about 0.6 m/s, researchers report online today in The Journal of Experimental Biology. But when the team recreated the vibrations produced by a single termite using a computer and device that produces low-frequency pulses through the mound passageways, they found that after just 40 cm, the signals were no longer strong enough to be picked up by other termites. Because worker termites can register drumming alarms meters away, the researchers suggest that the soldiers use social reamplification to extend the life of the signal. Like how the wave spreads through a crowd, soldier termites respond to the drumming of nearby nestmates by drumming themselves until every worker is alerted of the attack.