Super feelers: the mighty termite
In our last report on animal supersensors, Beth Mortimer from Oxford University puts forward her case for the fungus-growing termite...
Beth - Many animals whose sense of touch involves detecting vibrations along surfaces, but my vote for Super Sensor would go to a small invertebrate that does this particularly impressively - the attractively named fungus-growing termite (Macrotermes natalensis).
These termites live in galleries, elaborate structures with exquisite environmental control that can be up to nine metres tall. Their vibration sense comes into play when predators attack the colony. When attacked, soldiers drum their heads against the ground, creating vibrations that propagate along the gallery walls. Other termites are sensitive to these signals. Soldiers will respond by drum,ing themselves; this creates a kind of Mexican wave of vibrations that amplifies the signal so it reaches more termites.
What has granted them Super Sensors status is their ability to detect the direction the vibration is coming from. Worker termites move away from the source of vibration, whereas soldier termites move towards it. The ability to detect vibration relies on detecting differences between senses in different places; for example hearing something louder or earlier in one ear rather than the other.
Termites detect vibrations through their legs, but the distance between their legs is under 16mm. This raises the question: how do they overcome the limitations of their small size? Researchers from Ruhr University in Bochum, Germany designed a clever experiment to answer this.
Termites were placed on a split platform where vibrations into the legs on either side of their body could be independently controlled. They show that termites detect a time difference between their legs, so the side of their body that detects the vibration first points towards the source. The termites are remarkably sensitive, able to detect time differences as low as 0.2 milliseconds. The sensory systems of these termites have, therefore, compensated for their small dimensions illustrating that being small doesn’t stop you being a Super Sensor when it comes to touch.