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What is the Jacobson's Organ?

The Jacobson's Organ, or vomeronasal organ, is a fascinating part of animal anatomy, key to detecting pheromones and influencing social and reproductive behaviors. Found in many mammals, this chemoreceptor sits in the nasal cavity, silently shaping interactions. Intrigued by how animals communicate without words? Consider the subtle power of scent and its mysterious pathways in the animal kingdom. What might this reveal about our own senses?
Sheri Cyprus
Sheri Cyprus

The Jacobson's organ is located on the roof of the mouth in reptiles and mammals. It is also called the vomeronasal organ. This organ works by sensing the chemicals such as pheromones.

Pheromones are the chemicals that a living organism emits and that organisms of the same species can detect. Scientific research has revealed that plants, vertebrates and insects communicate in this chemosensory way. For example, the female silkworm signals potential mates by releasing the pheromone bombykol, first discovered in 1959 by Adolf Butenandt. When bees swarm, it is in response to other bees that emit pheromones as an alarm.

Some species of bat do not have a fully functioning Jacobson's organ.
Some species of bat do not have a fully functioning Jacobson's organ.

Reptiles and mammals use their Jacobson's organ to sense pheromones. Elephants touch the tips of their trunks to this organ to enact their chemosensory perception of things. A lion uses it for sensing sex hormones, and will often open its mouth to sniff the pheromones it senses.

The Jacobson's organ also helps some animals perceive other chemical compounds besides just pheromones emitted between species. For instance, snakes find their prey by using it. A snake places its tongue on the two pits in the roof of its mouth after having its tongue in the air to allow it to properly sense the direction of its prey. The reason snakes have a forked tongue is so that the tongue can touch these pits. The deeper the fork in a snake's tongue, the more the snake uses its Jacobson's organ.

Elephants touch the Jacobson's organ with their trunks.
Elephants touch the Jacobson's organ with their trunks.

Snakes have a fully functioning organ, but humans and some species of bats do not. The vomeronasal organ develops in the fetus, but then does not continue to develop fully. Researchers have found that some people may have at least a partially functioning one, but other researchers consider only a fully functioning Jacobson's organ as counting as having one, so these results are controversial.

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Discussion Comments


When you see your dog doing little inhalations, you know what I'm talking about - the jacobson's organ is being utilized. They're "sniffing" out the area.


I heard about this organ while traveling in Australia. I was told the Aborigine people have this organ but it's not developed anymore due to evolution; the way we live now doesn't develop it. Supposedly all people are born with it.


If you think your cat or dog is being cute when it seems to curl its lips back, you're wrong! That is one way the animal exposes this organ, in order to get a better whiff of the chemicals it's figuring out.


@Penzance356 - I agree with you on the point that as human beings we can use our senses and speech ability to interact with the environment and others within it.

However, I also think we have remnants of this organ in our bodies. Perhaps it has been made partially redundant through evolution, rather like the appendix?

I am always reading about how important pheromones are in attracting the opposite sex. There's got to be something in that which relates to this topic.


This is a fascinating article and a great read. I came across this term in a crossword recently and was curious about the meaning.

Perhaps animals which can communicate through speech, as humans do, have no need for a Jacobsen's organ.

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    • Some species of bat do not have a fully functioning Jacobson's organ.
      By: cheri131
      Some species of bat do not have a fully functioning Jacobson's organ.
    • Elephants touch the Jacobson's organ with their trunks.
      By: tiero
      Elephants touch the Jacobson's organ with their trunks.