The popularity of tarantulas as pets has increased tremendously over the past couple of decades. The increased demand for these large hairy spiders has led to many different species becoming available to the hobbyist.
Tarantulas are undemanding and exotic pets. They all belong to the Theraphosidae family that contains about 900 different species. They can be found in both deserts and jungles, living in trees or on the ground and ranging from the tropics to more temperate regions.
This of course means that one kind of tarantula can have very different environmental requirements and behavior than another. Learning the specifics for any species that you plan to keep is the key to keeping these pets happy.
One way tarantulas are broadly categorized is by where they come from. They are grouped as either New World species, which come from the Americas, or Old World species that can be found everywhere else except Antarctica. A big difference between these two groups is that many of the New World Tarantulas have irritating hairs that they usually flick into the air when threatened and the Old World species don't. Lacking this means of self-defense many of the Old World species rely on elaborate threat displays, rearing up and waving their forelegs at potential adversaries.
Remember that all tarantulas are venomous and that the strength of their venom as well as the likelihood to bite varies considerably by species and individual. This is a good enough argument against unnecessary handling but most tarantula injuries ranging from a cracked "shell" to lost limbs are also a result of handling. These normally occur from jumps or a startled handler attempting to prevent escape.
Another way tarantulas are categorized is where they live. There are terrestrial varieties that spend most of their time on the ground, arboreal tarantulas that live in trees and bushes and burrowers that like a nice comfy hole to peer out of. Quite a few don't fit neatly into a single category so some are designated as semi-arboreal if they split their time between roaming the ground and climbing through the vegetation.
The burrowers are designated as either opportunistic burrowers or obligate burrowers. The opportunistic burrowers are happy crawling around at ground level but won't pass up a good hole if they see one, most often renovating a natural depression or the abandoned burrows of other small animals. The obligate burrowers, there are only a couple of species, absolutely can't do without a good spider hole.
Tarantulas in general don't see very well and feel exposed if their enclosure has a lot of open space. A 10-gallon aquarium is more than enough room for almost all. Smaller plastic creature habitats are also suitable especially for smaller individuals. These have the benefit of a built in securely latching lid to prevent escape. Decorations should be easy to climb and secured from toppling to prevent injuries.
The material that covers the bottom of the enclosure is called the substrate. Some type of substrate or bedding is required for terrestrial species and should be at least 4-6 inches deep for species that are known to burrow and around 2 inches for those that don't. Arboreal species don't require substrate and fill their enclosure with webbing making it difficult to change and clean. Sterilized soil, vermiculite and peat moss are common substrates along with coconut fiber. Cedar shavings are toxic to your tarantula and should never be used.
Most species are comfortable at 70°-80°F but being cold blooded they appreciate a range of temperatures in their enclosure called a temperature gradient. Placing a heating pad at one end of the enclosure allowing the tarantula to find the temperature that suits them normally provides this.
Tarantulas are also sensitive to humidity especially when they shed their exoskeleton in order to grow. They are not normally big drinkers but a water bowl along with periodic misting will help to maintain humidity in the enclosure. The bowl should be shallow and easy to climb out of to prevent trapping and drowning the tarantula. Species from dry regions usually prefer a 50-60% humidity level while those from more moist environments prefer a 60-70%.
Tarantulas don't build your typical Halloween spider kind of web instead they string webbing around the entrance to their hiding space that lets them feel their prey instead of relying on their poor eyesight. The tree-dwellers tend to produce the largest webs. In nature tarantulas may eat small rodents, birds or reptiles but their main diet is usually insects.
They inject their live prey with fluids that liquefy their insides and then drink their meal. In captivity a few crickets 2-3 times a week most often make up the bulk of the tarantula's diet. This doesn't provide the nutritional variety that a more natural menu of random insects does so the crickets should be fed supplements to provide a balanced diet. This is called "gut loading" as opposed to "dusting" where the prey is coated with powdered supplements before feeding. Since they drink the insides of liquefied prey coating the outside which is left behind isn't very effective.
General care consists of 2-3 feedings per week. Uneaten prey and the remains of their meals should be removed daily. Misting should be done as needed to maintain humidity but never enough to keep your spider walking around with wet feet. The specie's preferred humidity level, enclosure placement and set up, particularly the type of substrate used will determine how frequent misting is required. Surfaces inside the enclosure should be wiped down weekly and the substrate should be changed monthly to control mold and bacterial or insect pest.