Author: Kurt Treftz, Cascade Pest Control
While home and business owners might not find much to love about rats – the beady-eyed rodents that gnaw, spread disease, and invade our dwellings – there are some intriguing facts about this ubiquitous animal. Recent studies continue to shine a light on these fascinating critters.
Rats have long been known for a keen sense of smell, but you might not know how amazing their smell is.
Key Features of a Rat’s Sense of Smell
Olfactory System
A rat’s highly sensitive olfactory system is equipped with smell receptors and olfactory neurons that line their nasal passages. Cilia are a hair-like receptor that lines the passages. They bind odors and trigger a neural response. Rats have just less than 1500 olfactory receptor genes. (For comparison, humans have around 400 and dogs around 1000.)
Vomeronasal Organ (VNO)
Along with the olfactory system, rats have a vomeronasal organ that detects pheromones. Located in the thin ovoid space in the lower portion of the nasal passage, the VNO receives information from rats sniffing and tasting. This additional layer to rats’ sense of smell allows them to key-in on pheromones in their environment. Pheromones are chemical substances released by an animal (usually in response to a stimulus) that then evoke a behavioral or physiological response in other of the same species.
Ultrasonic Vocalizations (USVs)
Known as the “Jedi-rat” phenomenon, ultrasonic vocalizations may also be part of a rat’s phenomenal sense of smell. This ground-breaking hypothesis proposes that rats don’t just use sound to communicate (like social communication or courtship rituals), but to manipulate their olfactory environment. By producing a high pitch sound (USV), rats cause airborne particles to cluster, which may enhance their reception of pheromones and other smells..
Key Smells in a Rat’s Repertoire
Pheromones
As mentioned above, rats are particularly sensitive to detecting pheromones from other rats. They can tell when their fellow rats are stressed or anxious. The rats communicate through these chemical signals, which are detected by the VNO. They can share information on reproductive status, danger, and social standing.
Food Sources
Rats spend most of their waking hours searching for food. Their keen sense of smell helps them locate food sources in hard-to-reach locations. They can even locate food inside a house when they are outside. Since rats are born blind, they learned to rely heavily upon their sense of smell from the very start. This never seems to leave them.
Survival & Navigation
Their keen sense of smell helps to keep rats alive. They can scent out predators, like large birds, cats, snakes, and humans. Rats can also navigate their environment with their sense of smell, especially in limited visibility settings. Their heightened sense helps them to hide from danger and stay out of trouble.
Weather Changes
Rats can sense changes in weather conditions, such as temperature drops and approaching storms. This helps them seek shelter before they are caught in a dangerous situation. Unfortunately, this can mean that a rat will find your home a welcoming haven from difficult weather.
Trained Scents
These surprisingly intelligent creatures have been trained to scent various specific scents. Rats can be taught to seek out explosives like land mines as well as illegal poaching like elephant ivory, rhino horn, and pangolin scales. They can also scent human diseases like tuberculosis and lung cancer. And a rat can remember these scents for several months without renewed exposure.
Non-target Odors
Rats can also be trained to differentiate between target and non-target odors. They can identify coffee beans, electric cables, and washing powder, which are often used by smugglers to hide the scent of target odors. In one study, rats could pick a target scent out from among 146 non-target aromas. And they remember it for up to several months without encountering the scent again.
Ultrasonic Vocalizations Enhancements
The use of these high-pitched vocalizations may allow rats to fine-tune their already impressive sense of smell. They stir up and cluster certain smells in an almost “Jedi-like” manipulation. They can then create new information pathways by altering their environments and controlling molecular particles they encounter through sound.
Implications for a Rat’s Sense of Smell
Rat Control & Behavioral Insight
Knowing how rats use their sense of smell can give humans insights into controlling them. Baiting traps, creating deterrent boundaries, and reducing attractants can be important ways that knowledge of rat biology can help control their behavior.
Applications
- Psychology: Rodent vocalizations and scent receptions may have critical implications for human disorders relating to communication, social behavior, and emotional processing, like anxiety, depression, schizophrenia, Parkinson’s disease, and autism.
- Engineering: Rat’s USV could also provide insights into biology and engineering, especially fields like particle manipulation, anotchnology, and even air filtration.
- Law Enforcement: These rodents can be trained to sniff out drugs and explosive devices. Rats’ keen sense can also be used to cut down on illegal wildlife trade. Current tools like X-ray scanners and scent detection dogs are expensive, time-intensive, and thinly-stretched. Rat could help fill the gap, as they are small, easily trainable, and cost-effective.
- Medical: Rats’ biosensors may also be used to detect diseases like cancer & tuberculosis.
As scientists continue to study these amazing rodents, they learn more and more about what rats are capable of doing. Even though we don’t want them rooting around our trash or camping out in our homes, we can still appreciate what rats offer the world with their keen sense of smell.