V is for Vomeronasal Organ (VNO)

dekays 2 c

As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is V for Vomeronasal Organ (VNO) as illustrated by this De Kay’s Snake or Northern Brown Snake (Storeria dekayi), native to the eastern US, Mexico, Guatemala, and Honduras, and although not recorded, one would expect it to also be found in Belize.

The vomeronasal organ (VNO), or the Jacobson’s organ, is an auxiliary olfactory sense organ that is found in many animals, including all snakes and lizards, plus many mammals.

Snakes use this organ to sense prey, sticking their tongue out to gather scents and then touching it to the opening of the organ when the tongue is retracted.



Salamanders, like this Eastern Red-backed salamander (Plethodon cinereus) perform a nose-tapping behavior to activate their VNO.

sal 1c

and certain species of freshwater turtles, such as the Yellow-bellied Slider (Trachemys scripta scripta) from the southern US, and the Twist-necked Turtle (Platemys platycephala) from the Manu region of Peru, use this organ to use their sense of smell underwater.

Trachemys scripta c

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The De Kay’s Snake is the only North American snake whose binomial is a double honorific: Storeria honors naturalist David Humphreys Storer (1804-1891), and dekayi is in honor of American zoologist James Ellsworth De Kay (1792–1851)

dekays c


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