SEATTLE - They are the castoffs among castoffs, the lowest pets on the totem pole, the afterthoughts.

Erika Schultz / The Seattle Times

Edgar, an adult male rat, is one of many small animals up for adoption at the Seattle Animal Shelter. A posting on Edgar's cage described him as curious, smart and gentle.

They can be creepy and crawly and, well ... sometimes kind of gross.

We're talking about guinea pigs, mice, rats you know the type. Seattle Animal Shelter workers simply call them "critters," shorthand for anything that's not a dog or a cat. Rabbits? Critters. Goats? Critters. Ditto for roosters and hamsters.

These small creatures sometimes get short shrift, and can take extra time to adopt out, shelter workers say. So last year, the shelter began showcasing them as part of its "Cool City Pets" series of open houses. On the third Saturday of each month, critter specialists give primers on their feeding, handling and care, trying to convince potential adoptive families that they can make excellent pets.

It isn't always an easy sell.

"You don't have to be so afraid," one girl says, slightly annoyed, to her little sister. They had just entered the critter room, where about a dozen cages hold some of the shelter's bunnies, hamsters, rats and gerbils. One rat has nibbled the note on top of her cage, unknowingly eating holes in her own biography.

"This is (blank) a gentle sweet and (blank) rat," the paper now reads.

The shelter's critter population fluctuates.

Critter litters tend to be bigger than cats' or dogs', said Michael Kokernak, animal-care officer. Sometimes, he said, people come home from the pet store with what they thought were two males, and "before you know it they have 30 hamsters."

As with the shelter's cats and dogs, a space shortage means some of the critters are in foster care.

"It gives them a chance to get out of their cages and kick up their heels," explained Suzanne Rubins, the shelter's "critter team leader."

Early in the afternoon, Isabel Schuchardt bounded into the critter room carrying a notebook covered in kitty pictures. A die-hard animal lover at age 10, she proceeded with deliberation, researching the needs and traits of enough breeds for a menagerie. She had a list of questions for shelter workers.

"We're thinking of getting, like, a chinchilla or a flying squirrel or a rat," she explained, practically breathless with excitement.

"We have three cats already. And a dog. And two tadpoles and three triops," a creature she describes as prehistoric and her dad describes as "kind of like a sea monkey but bigger."

She's been to the shelter two or three times but is waiting for the perfect pet. Although she's never seen a flying squirrel, she's leaning toward them. "They get used to your heartbeat and smell," she said. Alas, the shelter has nary a one.

"You guys do know that rabbits poop and pee, right?" Betsy Rand told her two daughters, who were interested in bunnies and dogs. They left empty-handed, but had their eye on a couple of rabbits.

By midafternoon, Lisa Drake of Wallingford decided on a bunny that was so calm and people-oriented that it sat in her lap for a half-hour.

"I have a dog and two kids," she said. "Why not have a bunny, too?"

She mentioned later that the family also has seven chickens.

Drake glanced once again inside the cage, and there was momentary shock. "Bun-bun," as her daughter had already deemed her, was lying on her side, looking quite immobile.

"Sometimes they just keel over like that," Kokernak explained. "Like they died."

Happily, Bun-bun was alive and well and on her way to a new home.