GROTON — He needs lots of sleep. He requires food for motivation and can quickly become an olfactory nightmare.

He doesn’t walk so much as waddle. Without notice, he shakes his head from side to side, sending strings of spittle somersaulting through the air.

His eyes? Bloodshot.

“We like to say he’s beautiful in his own way,” says Heather Hill, who, with husband Gary Green, owns the 4-year-old English bulldog.

Tank points his head toward the ground and expectorates loudly.

Not everyone on TV is glamorous.

Tank makes his television debut this week on the fourth-season opener of the popular PBS kids’ show, Fetch! With Ruff Ruffman. He is the only live-action dog in the series, and plays, well, a dog named Tank. Tank, who can high-five on command, plays a production assistant to the show’s animated canine star, Ruff Ruffman.

The show, which airs daily on Boston PBS affiliate WGBH-TV at 5:30 p.m., mixes animation with live action. Its kid stars chase science challenges in a reality game-show format. The show, aimed at 6- to 10-year-olds, is watched by 2.9 million viewers each week, according to WGBH-TV.

On the show, Tank replaced Hill’s other dog, a basset hound named Riot. On the show’s first two seasons, Riot played Murray, Ruff Ruffman’s assistant. But in November 2007, Riot died.

Hill, a 37-year-old freelance writer, also tends to her 9-month-old daughter, Samantha, and a second dog, a basset named Jeremy. She also does work with New England Basset Hound Rescue.

WGBH-TV producers initially contacted Hill before the show began shooting, looking for a basset. She didn’t have to look far. Riot was cast as Murray.

When another of Hill’s dogs, Brutus, died, Hill found Tank, nearly 2 years old, online. He was rescued from Connecticut and fostered by a family in Vermont.

“We’re just not a one-dog household,” Hill says. “My husband saw his sad tale and that was it. He had a few health issues that hadn’t been addressed properly. But with a face like that, we had to have him.”

He arrived in January 2007. Riot died nine months later.

During a shoot for Riot at Hill’s home (then in Westford), the Fetch! crew got to know Tank.

He is an endearing fireplug at 65 pounds.

The producers “fell in love,” says Hill. “How could you not?”

He was cast in season four without so much as an audition.

In the season opener, Tank dons a production headset and flips his tongue up and down animatedly. He has also been filmed pulling a wagon and rooting around in a mailbox, says Hill. Tank pops up in the season opener three times.

The late Riot — whose resume also included a Comcast commercial — gets a farewell in a story line that sees him quit the show.

“There’s one where he wears a Patriots’ jersey,” she says. “He’s had a few wardrobe changes. But he usually wears a muscle shirt with the show’s logo. Which is a tight squeeze. It takes two of us to get him into it.”

Hill figures the crew has filmed enough Tank so far for six episodes.

Unaware of his stardom, Tank coughs up a ball of phlegm.

His acting is motivated by foods more than cerebral methods.

“It takes a lot of cookies, hot dogs, Snausages and cheese to get him to do things,” Hill says. “I think he likes the attention.”

He earns a stipend for each appearance. His first paycheck earned Tank a new bed.

He sleeps “a lot,” says Hill. Not only is every waking breath audible, but at night, Tank “just about blows the roof off with his snoring.”

Relegated to a room downstairs and on the other side of the house from Hill and Green, “even then we can still feel the reverberations.”