If you're a parent, you know that sooner or later your child is going to ask for a pet. Of course you want to give in -- but how can you get a critter without taking on a whole new care-and-maintenence job? Try one of these easy-to-care for starter species.

1 Ants

For a lesson in not only pet-keeping, but society, consider an ant farm. The ant colonies -- made up of a queen, winged males and workers, each with their own role to play -- can thrive in a variety of homemade environments, ranging from mason jars outfitted with moist dirt and food scraps to plaster nests constructed with modeling clay, plastic tubing and a wooden frame. Planet Pets (www.planet-pets.com) offers good step-by-step instructions for obtaining your ants and creating your own setup.

2 Geckos

For older kids (at least five years of age, suggests Dr. Victoria Hollifield at Best Friends Veterinary Hospital in the District) and more of a commitment, consider a leopard gecko. These black and yellow spotted critters from India, Pakistan and Afghanistan are friendly, docile creatures that grow to be about eight inches long and generally live about five to seven years -- though some have lasted 20. One thing to watch: They are an investment -- a leopard gecko with a fully-outfitted, properly-heated tank will set you back $150-$200 (avoid housing males together; they get territorial), and, because they eat live food, be prepared to buy them crickets, mill worms or wax worms every week. You'll also need to teach your kids to always wash their hands after playing with them. Reptiles can carry salmonella.

3 Guppies

Attractive, engaging fish (the males have long, colorful tails) that breed easily and give birth to live babies, guppies are the ultimate in low maintenance. They like water at 72 degrees Fahrenheit and live for about two years. They're generally sold in male and female pairs for about $5, and up to 30 guppies can live happily in a 10-gallon glass tank with a light, water filter and gravel (about $65). Feeding them is easy, too; guppies eat flake food with the occasional brine shrimp or worm supplement. Just don't forget to keep it coming. According to Ken Yuen at Totally Fish in Aspen Hill (301-598-2229), under-fed guppies may munch on their babies -- something you surely don't want your own to see.

4 Hermit Crabs

Living in unoccupied mollusk shells and spending much of their time burrowing in sand or gravel, hermit crabs give the term "introvert" new meaning. But if handled regularly, they make friendly, curious pets who will happily climb on your hand, arm or furniture. The Hermit Crab Association (www.hermitcrabassociation.com) suggests buying a few (they're about $5 each) and keeping them in a 10-gallon aquarium with a lid and sand or gravel substrate (about $30). Despite their name and gentle nature, they love to travel in large packs, even piling on top of each other for fun. Make sure to keep plenty of spare shells in the aquarium; when one crab changes shells it causes a chain reaction and they all start moving houses.

5 Rats

No, really. The undiscovered pet for children, rats are smart, affectionate, social animals that are often compared to small dogs in intelligence and attachment -- they've been known to snuggle with their owners. These four-legged friends live three to five years, are nocturnal and love the company of other rats. But unless you want a posse of little ones, keep the males and females separate. An entire setup -- cage and all -- will cost about $50 or $60. Jason Griffin at the Westwood Pet Center in Bethesda (301-654-0604) suggests providing plenty of toys like blocks of wood, cardboard, coconut shells and ropes for chewing -- rats' teeth grow steadily like fingernails.

Ronda Kaysen

"Don't be put off by my bestial expression. I am sociable and lovable and want to be your child's new best friend."