If you buy a small spiderling, you probably are going to have to depend on the experience of the seller or breeder as to whether it is healthy or not. But if you are interested in an imported or captive-bred spider that is half grown to adult, then you can at least get an idea if the animal is healthy. Healthy tarantulas are shy, but they are obviously alert—they tend to lurk at the front of their burrows or hiding spots, ready to duck back in if threatened or emerge to snap up food. They never just He exposed in a corner with their legs tucked under their body—such a tarantula is sick and likely to die in a few days.
Don’t worry about bare patches on top of the abdomen in American tarantulas—these just represent where the tarantula has swept away the urticating hairs. After the spider molts (usually within a year if adult), the bristles will return in all their irritating glory. If the end of a leg is missing or deformed, this also may not make much difference once the tarantula eventually molts and replaces the leg. Sometimes you can get “slightly defective” tarantulas for a bargain price, and they often make good, long-lived pets. Sometimes, of course, they die of complications during their molt, the decision is yours.
Never buy a tarantula that is not eating. You can look for dried cricket or mealworm husks in the cage (though hopefully the seller has made an effort to clean the cage), or you can ask that the tarantula be fed a cricket so you can see it eat. Be aware that not every tarantula eats every week, especially older adults, so you may have to come back later when the tarantula is more interested in food.
The Male Problem
The usual suggestion is to not buy an adult male tarantula because males usually die in six months to two years from when they become sexually mature. Unfortunately, many tarantulas are collected when roaming the roads, and these are almost always males looking for females. Males tend to be high-strung, as their little brains are overwhelmed by desires of mating; their only goal is to find a female and mate. They may not eat and may burn great amounts of energy just continually moving around the terrarium looking for a way out.
You will have to pay more for sexed young female tarantulas, as they have long lives to live—many species have females that can live twenty years or more. Young males (sexed correctly at least two years before they have their final molt and become sexually mature) can make good pets if reasonably priced, but take them with the knowledge that they will not live as long as females will. Of course, if you are not really willing to be saddled with a female tarantula for twenty years, a young male might make an excellent pet for a few years.