Their looks border on the grotesque, and maybe there's some sort of morbid curiosity that keeps people glued to the exhibit. But even if the rats weren't such a visual oddity, their insectlike work ethic and teamwork attitude is enough to keep visitors spellbound.
When two mole rats meet in a tunnel too narrow for both to navigate, one will back up to accommodate the other, almost like the "You first -- I insist" act of the polite cartoon gophers. And the rats' industrious digging rivals a gopher's. They keep their whiskered snouts to the grindstone, tunneling constantly. "Diggers" use their four giant incisors as backhoes and bulldozers (their lips close behind the teeth, keeping dirt out); "sweepers" tidy up the tunnels; "volcanoers" kick excess dirt to the surface; and "soldiers" guard the nest from predators, such as snakes.
In the wild, teams of mole rats dig miles of tunnels. Main highways are wide enough for two-way traffic, smaller side roads connect them, and shoulders offer turnaround points. The tunnels connect various bathroom chambers and a nest chamber. In the Dreher exhibition, pine shavings are strewn about to keep the critters busy.
"People love to watch their activity," relates Laurie Smith, Dreher's education curator. "They are constantly kicking the shavings out of their tubes, doing this kicking and sweeping with the back legs." If they slack off, the queen, the only breeding female in the rats' beelike society, plays foreman. "When she approaches them, they all freeze in place," says Smith. "She nudges them with her head or bites them, though not hard."
The virtually blind animals swing their heads back and forth while moving around the colony as if struttin' through the 'hood. It's tough to look cool when you're that ugly, but this behavior actually keeps their whiskers in contact with tunnel walls to help them navigate.
"They are a crowd pleaser," says Smith, who first witnessed visitors' fascination with the minuscule mammals at the Philadelphia Zoo. That's where she and her long-time companion, zookeeper Dave Wood, worked before coming to Palm Beach two years ago.
Wood, in fact, was the first to get the rats to breed while on display. After all, rats have urges, too, and Wood found they responded well to the primal suggestiveness of rock music. Now they get busy to the strains of Van Halen and Led Zeppelin pumped through their habitat.
Whatever their romantic/musical tastes, the tunes help the animals in another way, explains Smith. "By playing the music 24 hours a day, they become conditioned to it, and [outside noise] no longer inhibits their natural behavior."
Once the ridiculous-looking rodents get acclimated, it's still not a free-for-all love fest. The queen chooses just one to three breeding studs by sniffing them and feeling them over -- sort of like picking out fruit in the produce aisle. She then proceeds to have litters of up to 27 babies every 88 days.
"The queen looks like she's swallowed a golf ball when she's ready to give birth," says Smith. "It looks like a scene from Alien. Her skin is so stretched, you can see them squirming around in there, all of the little heads."
Mole rats got a popularity boost from a more current film, 1997's Fast, Cheap, and Out of Control, in which one story line revolves around a man with a mole rat obsession.
The film came out in November, but researchers started studying the rats' insectlike behavior in 1976. In addition to their societal setup, scientists found the rats had other nonmammalian traits. Though not truly cold-blooded, they can't control their body temperature internally. Not a problem when you live underground in semiarid regions of Africa, where the temperature of the soil remains a constant, toasty 86 degrees.
In Dreher's mole rat condo, the air is kept around 90 degrees. And even when the zoo is closed, mole rat lovers can get their fix. The National Zoo in Washington, D.C., where the mole rats at Dreher came from, has a "mole rat cam" linked to the Internet.
Phallic comparisons aside, the rats are sexy in their own homely way. When you accept them for what they are -- extremely cooperative, hard-working creatures who like to rock out -- what's not to like?
-- John Ferri
The naked mole rat exhibition is at Palm Beach Zoo at Dreher Park, located on Summit Boulevard just east of I-95 between Southern and Forest Hill boulevards in West Palm Beach. Admission is $4 to $6. Hours are from 9 a.m. to 5 p.m. daily. Call 561-547-9453.