What is a herpetologist? And why does the Commonwealth need an official state herpetologist? Ask Michael T. Jones, an expert in amphibians and reptiles and a “herp’s’’ best friend — whether it’s in the wetlands or fields. As Massachusetts’ only full-time herpetologist, Jones is a sort of amphibian crusader in the Division of Fisheries & Wildlife, ensuring that these bellwethers thrive despite all sorts of threats: roadways, pollution, habitat loss, climate change, and even illegal pet trade. Globe correspondent Cindy Atoji Keene spoke with Jones about his love for salamanders and newts and why that impressive-looking snake in the garden is nothing to fear.

“First, about that snake that’s setting off alarm bells. Seeing a northern water snake for the first time can be concerning — they have similar markings to a cottonmouth — but they’re actually nonvenomous and harmless and will scurry away when approached. I often answer concerns like this, as well as queries about snapping turtles, milk snakes, and others.

“Overall, my goal is to ensure the persistence of Massachusetts amphibians and reptiles. There is clear evidence that formerly abundant and widespread populations are now declining, including 44 species that are native to Massachusetts. Probably the rarest is the bog turtle, which only lives in small wetlands with ground water calcium input — they’re only in Western Mass. and fewer than 100 [are] left in the state. The bog turtle is one of the smallest turtles in the world and greatly prized by collectors who may pay many hundreds for a live animal.

“The high-end black market in reptiles seems to get worse every passing year, and that’s part of the context that I work in. I’ve been studying amphibians and reptiles for about 14 years, although I’ve been in my current position only four months.

“I grew up in Andover where there was a little kettle pond just down the street from me. I was fascinated by the turtles that lived there and have since studied turtles all over the continent. Turtles have very ancient lineages and are a constant reminder of humility and gigantic time tables.

“My field work takes me from the Berkshires to Cape Cod, and I operate around a seasonal schedule with most species very active in the spring. We use radio telemetry to track animals, and I can see some of them years after I first marked them. We microchip some of the more endangered turtles and might also take small blood samples to allow studies of genetic diversity.

“At the moment, there are 14 species on the [state’s] endangered species list. It would be a real shame to lose any of them. At this point, we’ve only lost the five-lined skink — it’s still in other states but no longer here in Massachusetts. We don’t fully know the implications of losing a species that might have been around for millions of years. It would be an easy mistake to make but a mistake that would be very hard to undo.’’

Cindy Atoji Keene can be reached at cindy.atoji-@gmail.com.