Fascinating flehmen - how a smile opens a world of information

Spend enough time on safari with Singita and you will notice that animals have a language all their own. Sometimes it’s subtle, like the flick of a tail or an ear. Other times, it’s impossible to miss. One of the most intriguing and often amusing behaviours you might see on drive is the Flehmen grimace. At first glance, it looks like the animal is pulling a funny face, curling back its upper lip, wrinkling its nose and lifting its head as if it just smelled something unpleasant. But behind this comical expression lies an incredible sensory tool that gives animals an edge in the wild.

The Flehmen grimace is all about information gathering. When a male lion pauses mid-trail and makes that face after sniffing a patch of ground, or when a zebra stops to investigate the scent of another, they’re not just being dramatic. They are processing chemical signals, messages left behind by other animals. These signals, known as pheromones, tell a story. They reveal who passed through, whether they were male or female, young or mature, healthy or stressed, and even if a female is ready to mate. It is a silent communication network layered across the bush, and the Flehmen response is the key that unlocks it.

The reason animals make this strange face is because of a remarkable sensory structure called the vomeronasal organ, also known as Jacobson's organ. Located in the roof of the mouth or the nasal cavity, depending on the species. Its job is specifically to detect pheromones. While the nose handles everyday scents like food or the smell of rain, this organ is tuned to chemical cues that are heavier and more complex. When a stallion lifts his lip or a leopard pauses to grimace at a scent mark, they’re effectively opening a direct channel to this organ, drawing the chemical molecules in and sending the information straight to the brain’s accessory olfactory system.

The accessory olfactory system is a specialized part of the brain dedicated to processing these pheromone signals. Unlike the main olfactory system, which interprets familiar smells, this pathway is designed to handle subtle, socially important information. It begins in the vomeronasal organ and feeds directly into the accessory olfactory bulb, a cluster of neurons that act like a translator for chemical messages. From there, signals travel to deeper parts of the brain linked to instinct and emotion, influencing behaviours such as mating, aggression, and even parental care. It’s an ancient and highly efficient system, allowing animals to make decisions in the blink of an eye based on chemical cues we humans can’t even detect.

For the animal, this momentary pause is like checking an unseen noticeboard. A male cheetah may discover that a rival passed through earlier that morning. A bull elephant could confirm if a female is in oestrus and ready to breed. Even prey animals use this information, often assessing the scent of others in their herd to understand stress levels or health conditions. It is a behaviour that can look a little humorous to us, but it plays a serious role in social bonding, reproduction and territory management.

Out here, where so much of life is written in scents and tracks, the Flehmen grimace is a reminder that the bush is full of messages we can’t always see or hear. Next time you’re on drive and see a lion, zebra or even a giraffe pull back its lip and freeze for a moment, you will know that it’s not being playful or aggressive it’s reading a chemical story only it can understand.