At least once a week, Marion Larson of MassWildlife gets an e-mail inquiry about whether a certain "pet" is legal. Occasionally, she receives a listing of an exotic pet advertised on craigslist.com, with a note asking: "Isn't this illegal?"

Now an information and education biologist with the agency, Larson has also been an environmental enforcement officer, so she's seen her share of seizures of animals that are prohibited as pets in Massachusetts.

There was the 80-pound bear cub that was removed from its house after someone dropped a dime on the owner. There's also been a fair number of reptiles, including alligators, that are prohibited in the state. Then, there was the bobcat kitten in a dorm room.

Often, the agency will get tips from veterinarians who are asked to treat an exotic animal. Vets risk losing their licenses if they are found to have treated such a creature.

Massachusetts has the most restrictive rules regulating the ownership of exotic pets in the country, Larson said.

What poses more challenges today is the growth of the Internet as a source for finding and buying such animals, some of which may be legal at their point of origin, but illegal here. In the Attleboro area, there have been cases where buyers purchase exotic pets legally in Rhode Island only to discover they are illegal once they cross the line into Massachusetts.

Separating owners from their exotic but illegal pets can be emotionally wrenching, Larson said. But the action is usually not meant to be punitive. "We're concerned about the welfare of an animal as well as what it may come in contact with," she said.

People who buy wild or exotic animals range from the kid who wants to take certain turtles home to adults who are searching for something unique or "cool." There are also "collectors" for whom obtaining the obscure or the exotic is an obsession.

"But there are animals that are appropriate and animals that are not appropriate," Larson said.

Collectors are among the reasons the box turtle has become a rare species, she said.

"The biggest problem is that people can buy on the Internet," Larson said. "You can't assume because it's posted there that it's legal."

At least some people, she said, call and check to see if an animal is legal in their state before they buy. Sometimes, people don't call until they move here.