The vast majority of termites are blind, but that hasn’t stopped these insects from being among the most successful species on the planet for tens of millions of years.
In fact, 90% of all termites among the more than 3,000 known varieties do not have any eyes at all. They don’t need visual sight since they spend the entirety of their lives deep inside the dark tunnels of their wooden host structures.
How Do Termites See?
In a sense, the term “blind” is a matter of definition or semantics. Think about it. If a creature without eyesight nevertheless has at its disposal multiple different ways to accurately perceive its surrounding environment, can they truly said to be blind?
Consider the way a bat uses its natural “bat radar” to send out echolocation signals. This allows it to expertly snatch fast-moving insects out of a dark night sky. Bats do not rely on eyesight at all, but they clearly are far from blind. Indeed, in many ways, bat radar ability is superior to eyesight.
The same can be said about the termite. They have evolved a number of biological skills and tools that allow them to expertly get everything done they need to get done, including navigating and shaping a world to their advantage.
Sight For The Privileged Few
Termites have a distinct social order and hierarchy. Those at the very top are granted the gift of eyesight. They are the queen and king termite. It is somewhat ironic that this privileged pair have visual capability since all they do is sit around, mate and lay eggs.
They don’t travel, lead their followers on patrol or even find their own food. Food is brought to them by the workers. It is uncertain why the king and queen termite should need the gift of sight — but they have it.
And get this: Even the termite soldiers are blind. They don’t have eyes, but their job is to defend the colony. That usually means taking on the termite’s greatest and most bitter enemy — the ant.
Ants that prey on termites enjoy full eyesight, and it must be said, they tend to have a tremendous advantage. Ants kill termites in large numbers on a regular basis.
They use them for food. However, soldier termites are able to provide a sufficient defense to at least maintain the integrity of the colony.
Eyes For The Skies
The only other class of termite to have eyes are the alates, or winged termites. This special breed of termite need lighted vision because their job is to fly away from their homes to locate new colonies and to mate.
Alates are both male and female. Two of them in a swarm will someday become the king and queen of a fresh colony. This may explain why kings and queens end up having workable eyes — because they started out as alates.
Other Non-Eyesight Sensing Modes
CC Image courtesy of Filipe Fortes on Flickr
Worker and soldier termites use a chemical method to perceive their environment. These chemicals are called pheromones. They facilitate a method more akin to smelling than seeing, although is it significantly different from what we normally think of as “smelling.”
Termites use their antenna to detect traces of pheromones that show them pathways representing where they need to go. Termites leave these pheromones behind like a trail of breadcrumbs for their pals to follow.
A pheromone trail is akin to a bright line which is easy for a termite follow — yet this bright line would be invisible to a creature using eyesight. It must be noted that some predatory ants have learned to “decipher the code” of termite pheromone trails, as reported in a remarkable study published in the proceedings of the Royal Society B.
Termites also use their pheromones to communicate messages to one another. They excrete these messenger chemicals from special glands in their chests.
Many different kinds of pheromone are each keyed to messages with specific meanings. Termites use intricately calibrated pheromones to invoke vivid communications which elicit a variety of social responses.
No Ears Or “Normal” Hearing Either
One might think that because termites are eyeless and sightless they would make up for it with excellent hearing — but they don’t even have ears.
Here again, the creative termite has opted for a novel and innovative way to accomplish a different kind of “hearing.” In many respects, termite-brand hearing is better than the way most other animals hear. Its a method that sounds almost like science fiction.
Termite transmit mechanical signals using special vibrations. Intriguingly, they build their system of tunnels in a way that expertly allows wood to transmit sound to one another.
For example, when soldier termites want to warn the entire colony of an impending invasion, they pound their heads against the walls of their tunnels.
This propagates a signal throughout the wood that has a precise pulse rate which repeats at a frequency of 10 to 20 Hz. The velocity of the signal is ~130 ms −1, and this is is attenuated by a ~0.4 dB per centimeter distance.
In other words, this signal is a 5-alarm fire drill for the entire colony. They respond by frantically retreating deeper into the interior of their colony.
The vibration also tells other soldiers where to go so that they can engage the enemy in battle — which is almost always against their most bitter rival — predatory ants, say E. O. Wilson and Bert Hölldobler in their Pulitzer Prize winning book, The Ants.
By the way, the remarkably subtle sound-frequency measurements of termites were accomplished by German research scientists Felix A. Hager and Wolfgang H. Kirchner. They reported their findings in the Journal of Experimental Biology.
Furthermore, the termite has developed an even a more fascinating, perhaps even astounding, way to “hear.” Termites can “tune in” to natural plant spores floating in the environment. They can “read” signals from these spores and then produce vibrational displays that will warn others in the colony that natural — or man made — poisons are coming their way. Then they can retreat to safety in deeper levels if possible.
This is one of the ways termites have adapted to the poisons designed by professional pest control experts who must keep coming up with new ways to battle the incredibly resourceful, adaptable termite.
No Sight — No Problem
It’s clear that 47 million years of evolution have equipped termites with powerful and amazingly creative ways to perceive their world that go well beyond what we think of as normal sight and sound.