At the outset, let's define exactly what the difference is between turtles and tortoises, for the terms are applied differently in different countries. And let's also understand an important distinction: While all tortoises are turtles, not all turtles are tortoises.
Tortoises are a family of shelled reptiles that bear certain rather identical physical characteristics. They are, with a few exceptions, creatures of dry land habitats, have heavy, highly domed carapaces (upper shells), club-like, non-webbed ("elephant-like"), feet, and move in a cumbersome manner.
(There are a few notable exceptions. They include the African pancake tortoise, a small, flattened, relatively agile species with a thin and pliable shell and a couple of species of hinge-backed tortoises that are associated with swamp-edge habitats.)
While a few non-tortoise turtles are also species of dry land habitats
box and wood turtles), most true turtles (painted, spotted, and map turtles) are semi-aquatic and a few (sea, soft-shelled, and Fly River turtle) are almost exclusively aquatic.
So, how you house your turtle or tortoise will vary according to the species of shelled-reptile you keep. Also bear in mind, that turtles and tortoises are long-lived. The life span of most exceeds 20 years and some are known to live for more than a century. Those routinely offered in the pet trade are babies. Most grow fairly large; some are huge as adults. Purchase a species that you can house conveniently throughout its long life.
Even when they are small, however, neither turtles nor tortoises are candidates for life in a tiny, plastic, palm tree decorated turtle bowl. Always provide these creatures with as much space as possible.
Because they emerge from the water onto banks or emergent logs and rocks to bask in the warm rays of the sun, most semi-aquatic turtles are termed "basking turtles." Basking allows these ectothermic ("cold-blooded") reptiles to elevate their body temperatures to optimum levels and assists in staving off respiratory ailments and ridding the creatures of external parasites such as leeches. Basking and drying also lessen the possibility of fungus and water-borne bacterial infections.
Soft-shelled and side-necked turtles may elevate their body temperatures by seeking sun warmed shallow water in which to lie and may seldom actually emerge from the water. The members of these families are not by definition actually basking turtles.
When a basking turtle has warmed sufficiently or is in danger of overheating, it will return to the water to cool and forage. This alternating procedure may take place several times daily.
To keep a basking turtle successfully, you must provide both smooth, illuminated and warmed, haul-out areas and enough space to really swim. Your turtle's quarters (including the water) must be clean and as bacteria free as possible.
From one to a few baby turtles can be housed temporarily in a properly appointed 10- or 15-gallon aquarium. The same number of 4-inch-long specimens will require a 30- or 40-gallon aquarium, and one or two adult turtles will need a 75- to 150-gallon tank.
Many hobbyists keep their pet turtles indoors during cold weather and outside in garden ponds when temperatures permit. Indoors or out, the cleanliness of the water in your turtle's tank will be maintained most easily by filtration and periodic changing. We use oft-cleaned sponge filters through which the tank water is drawn by large powerheads.
The more and larger your turtles, the more often the water will require changing. This holds true in a garden pond as well as in an indoor aquarium. When changing the water, do not start a siphon by sucking on the tube. To do so can provide an avenue for invasion by protozoa or bacteria. A self-priming pond pump is an ideal way to remove the water from either indoor or outdoor units.
Although many of the more commonly seen pet trade turtles are not especially cold sensitive, the water temperature should be maintained between 72 and 85 degrees Fahrenheit. The daytime surface temperature of the haulout should be 95 to 102 degrees. We provide this by using UV-B heatlamp bulbs.
Basking haulouts can be made of smooth weathered driftwood or a piece of tree limb (do not use cedar or other aromatic wood), or may be a smoothly domed rock, a piece of Styrofoam wedged firmly between the sides of the tank, or a commercially available plastic float. Whichever is used, it must be stable and provide enough surface for the turtle(s) to easily balance, move a little and dry completely. The commercially available textured plastic and other haulouts are more easily sterilized than driftwood.
Non-abrasive haulouts are especially important to leathery-shelled soft-shelled turtles. These interesting (and often feisty) turtles are especially prone to plastron (bottom shell) injuries.
Tortoises are distributed in tropical and subtropical areas of the world. Comparatively few species are available in the pet trade. Those most commonly encountered are the red-footed, the leopard, the African spurred and two species of hinge-backed tortoise. Although all can be handled, they do not enjoy be lifted from the ground. Do so only when absolutely necessary.
Until fully acclimated tortoises may be shy, withdrawing into their shell when lifted and remaining immobile for long periods (10 minutes or more). Allow these reptiles to make the overtures. As they become used to their pen and to the movements around them, they will become ever more confident, eventually coming to the side of their cage to greet you and accept food.
Leopard tortoises can attain more than 35 pounds in weight; African spurred tortoises may occasionally exceed 100 pounds. Red-foots usually top out at about 15 pounds and hinge-backs at only a pound or two. African spurred tortoises are also powerful diggers. Be sure you choose a tortoise species that is compatible with your available facilities.
Although tortoises do not grow quickly, they do continue to grow when actively feeding. One or two hatchling tortoises may be kept in a 15-gallon terrarium with a mulch or rolled corrugate substrate. Sheets of newspaper may be used, but this may not provide the tortoises with sufficient traction. This must be replaced when soiled.
As the tortoises grow, you will have to increase the size of the terrarium. One or two adult leopard or red-footed tortoises will need a cage having a bottom space of four by eight feet (the size of a sheet of plywood) and an adult African spurred tortoise will require even more space.
A 75-gallon capacity terrarium will suitably house one or two hinge-backed tortoises. A retaining wall of 18 to 30 inches (depending on the size of the housed tortoise) will effectively restrain your pet. A cage top will not be needed.
Leopard and African spurred tortoises are aridland species that should be provided with low-humidity quarters. Red-footed tortoises will appreciate a slightly more humid enclosure, and two of the four species of hinge-backed tortoises (Home's and forest) will do best in high humidity (and perpetually warm) situations. Bell's and Speik's hinge-backed tortoises are aridland species, however.
During the daylight hours, illuminate and warm one end of the cage. An ambient cage temperature of 76 to 82 degrees F is fine, but you should also have a hot spot warmed to 95 to 100 degrees F by a full-spectrum UV-B-heat bulb. Nighttime temperatures can drop by a few degrees and the heat bulb will be turned off. Provide a natural photoperiod.
Provide a shallow but sizable water receptacle for your tortoise to drink from and soak in. Since many tortoises regularly defecate in their water receptacles, change this as necessary.
Garden pens, greenhouses and spare rooms can also be adapted as a tortoise home.