There are several reasons for the popularity of gerbils as household pets. The animals are typically non-aggressive, and they rarely bite unprovoked or without stress. They are small and easy to handle, since they are sociable creatures that enjoy the company of humans and other gerbils. Gerbils also have adapted their kidneys to produce a minimum of waste to conserve body fluids which makes them very clean with little odor. The pets are incredibly industrious and will explore new environments, and they will build, construct, and enjoy elaborate networks of tunnels if given an environment that allows for it. This is easily observable as gerbils are active during all hours of the day, as opposed to the more nocturnal rodent pets. They can use everyday paper-based items, such as cardboard products and brown paper bags, into toys and nesting material.

Types of Gerbils

There are many different types of gerbils including:
The Mongolian Gerbil (Meriones unguiculatus)
The Fat-Tailed Gerbil or The Beer Mat Gerbil (Pachyuromys duprasi)
The Pallid Gerbil (Gerbillus perpallidus)
The Baluchistan Gerbil (Gerbillus nanus)
The Tristram's Jirds or Asia Minor Gerbil (Meriones tristrami)
The Charming Dipodils (Gerbillus amoenus)
The Persian Jirds (Meriones persicus)
The Sundervall's Jirds (Meriones crassus)
The Shaw's Jird
The Bushy-Tailed Jird

What are Jirds?

Meriones is a genus that includes the gerbil most commonly kept as a pet, Meriones unguiculatus. The genus contains most animals referred to as jirds, but members of the genera Sekeetamys, Brachiones, and sometimes Pachyuromys are also known as jirds. The distribution of Meriones ranges from northern Africa to Mongolia. Meriones jirds tend to inhabit arid regions including clay desert, sandy desert, and steppe, but are also in slightly wetter regions and are an agricultural pest.

What are Gerbils?

A gerbil is a small mammal of the order Rodentia. Once known simply as "desert rats", the gerbil subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats. Most are primarily diurnal[citation needed] (though some, including the common household pet, do exhibit crepuscular behavior), and almost all are omnivorous. The word "gerbil" is a diminutive form of "jerboa", though the jerboas are an unrelated group of rodents occupying a similar ecological niche. Gerbils are typically between six and twelve inches long, including the tail which makes up approximately one half of their total length. One species however, the Great Gerbil, or Rhombomys opimus, originally native to Turkmenistan, can grow to more than 16 inches (400 mm) in length. The average adult gerbil weighs approximately 2 1/2 ounces. As of August 19, 2003, officials in western China's Xinjiang Uygur Autonomous Region began releasing eagles to combat the damage they say the great gerbils have done to eleven million acres of grassland. Pet gerbils have an average lifespan of 2 to 4 years. Some have been known to live five or six years.

Differences between Jirds and Gerbils?

Jirds:
Adult Jirds range in size from 9 to 18 cm with a tail that is equal to or slightly longer than the rest of the animal. Weight varies widely by species but is generally between 30-100 grams.

Gerbils:
Adult Gerbils range in size between a rat, and a hamster. They look a lot like hamsters, but sometimes stand on 2 legs, and have a bushy tail. Body length 10-12.5 cm, weight 70-130 g.

*Some information sourced from http://en.wikipedia.org/