There is a general agreement among biologists that a reptile, a terrestrial vertebrate, ranks rather high in the evolutionary hierarchy of the animal kingdom, even though it is an ectotherm. Most would also agree that there is a certain fascination with reptiles, and even a mystique that arouses the curiosity of young and old. Indeed, the reptile houses of our zoological parks are very popular. It seems natural that living reptiles would be used in the classroom to stimulate interest in biology; however, in reality few classrooms actually have reptiles on display. In those few that do, the specimens are often improperly housed and cared for.
It is interesting to consider why these animals have been so largely excluded from the biology classroom and laboratory. Occasionally it is because some students or instructors may show fear or distaste at the prospect of examining, studying, or handling a reptile. More often, it is because there is no suitable housing for these animals. However, the chief reason seems to be a general lack of knowledge pertaining to the morphology and physiology of reptiles and to the related care and housing procedures, since not many universities offer courses in herpetology for the prospective biology teacher.
To create a vivarium, cover the bottom of the tank with 1–2″ of a suitable substrate. The ideal substrate is a loose, leafy potting soil or a mixture of moss and sand. These are natural looking substrates that allow the lizards to dig and root. Sand and soil can pose health problems if ingested, so food items may need to be placed in a dish to prevent this. The substrate should be kept moist at all times. However, it should only be damp to the touch and excessive wetness should be avoided. Mist the enclosure with a spray bottle once daily, more often if necessary. The relative humidity should be kept between 70 –90% when possible. Plants are also useful for providing hiding spots and increasing the relative humidity within the enclosure. The addition of several small hide boxes to the enclosure will provide shelter.
You may wish to construct your own vivaria, and these may be made of all glass or a combination of glass and plywood (see Figures 1 and 2). The all-glass type is made of sheets of single-strength glass, cut by your local glazier to the exact size, and then joined together with a bead of aquarium cement at all the butted joints. These joints are then reinforced with transparent tape at all corners (Figure 1). The second type is made of 1⁄2″ plywood cut to size, buttnailed at the joints, and then a piece of double-strength glass serves as the front. The back panel should be made of pegboard to permit free circulation of air. With either type, the top is made of wire mesh stretched between a frame of 1⁄2″ pine strips that will fit snugly over the top of the vivarium. The minimum size should be equal to a ten-gallon tank.
Since all reptiles are cold blooded organisms, the ambient environmental temperature dictates their body temperature, metabolism, and general health. Ideal enclosures will simulate the natural environment of the reptiles. This can be done by focusing a spot lamp on one corner of the tank to provide a thermal gradient throughout the tank. A “hot spot” will be formed in the area directly underneath the spot lamp and a gradual decrease in temperature will result as the distance from the lamp is increased. This allows the animal to control its own body temperature (thermoregulation) by moving toward or away from the “hot spot”. An accurate thermometer will allow you to monitor the temperature variances throughout the enclosure. An average temperature of 30°C (86°F) throughout is desirable with a decrease of approximately 10°C (20°F) at night. If additional heat is necessary, a heat rock or under tank heater may be used. A fluorescent lamp is also necessary to simulate the conditions of the lizards natural environment. It will provide the lizard with essential UV radiation and a photoperiod. The bulb should be a full-spectrum bulb that simulates sunlight so that the lizards can convert the UV rays into essential vitamins that are unattainable through the diet. The photoperiod should be approximately 14 –16 hours of light and 10 – 8 hours of dark.
The lizards, Suborder Sauria, are very diverse and consequently need a variety of living conditions to do well in captivity. One of the easiest lizards to maintain is the South American iguana from the Iguanidae family. Two other lizards that are extremely easy to care for are the monitor lizard from the Varanidae family, and the gecko, from the Gekkonidae family. Any of these three may be obtained from your local pet store and can be housed in a standard tengallon tank with a heavy earthenware bowl for water and newspaper lining the bottom of the vivarium. There should also be a retreat box of some kind provided for the animal to hide in. The temperature must be between 27 – 30°C (80 – 86°F) and may easily be maintained with a 75 W light bulb in a reflector. The iguana is an herbivore and, as such, will require lettuce and other greens. The other two species are carnivores and will need raw meat or dead mice. The food should be dangled in front of the carnivores with long tongs and not simply placed in the vivarium.
WARD’S sells two types of lizards that are also appropriate classroom pets. The American chameleon (green anole) is indigenous to the sub-tropical areas of the southern United States. Their range stretches from southern Florida north to the Carolinas and westward to central Texas. Subtle color changes are possible and their typical coloration is bright green or brown depending on their mood or health. Males tend to be larger and more robust than the females. They have gular pouches under their throats that are pink to reddish in color. The typical size of an anole is 6″, but large males may reach upwards of 81⁄2″ in length from the tip of its nose to the end of its tail. Anoles are generally semiaggressive and will bite if provoked. Bites are harmless and rarely, if ever, break the skin.
The green anole is an insectivore and obtains most of its nutrition from various insects. Crickets are an easily obtained food source; however, the diet should be varied when possible. Mealworms, spiders, sowbugs, and beetles are other good choices. The lizards should be fed every two days and the insects of choice should be dusted with a vitamin supplement every four days. The amount of food offered will vary depending on the number of lizards in the terrarium. Water requirements are nominal, since most anoles will drink droplets from leaves and branches in the terrarium after they are misted. If additional water is needed, a dropper system should be used. Some anoles will drink from a small water bowl, but others will not.
The size of the enclosure used to house these animals will vary depending on the number of lizards being housed in the enclosure. In general, anoles have minimal spatial requirements, although it is suggested that males not be kept together due to their aggression and territoriality unless an overlarge terrarium is used. However, one male can usually be kept together with several females. Any individual that exhibits anti-social behavior in the terrarium should be removed and isolated in a separate terrarium. The green anole is a hardy species and can adapt to survive in levels of humidity lower than 70% when necessary. They are also active climbers and for this reason several branches should be placed in the terrarium.
In addition to the chameleon, WARD’S also offers a yellow throated plated lizard. The yellow throated plated lizard is indigenous to the dry, rocky, semi-open environments of South and East Africa. The name is derived from the large bony plates or osteoderms located underneath the scales of the lizard. The lizards are usually brownish with yellowish-orange underjaws and two yellow stripes running along their back. These animals are generally docile creatures and rarely bite. Most are amenable to handling, although some are nervous, easily spooked, and difficult to pick up. However, all will settle down in time if given proper care and handled regularly. Plated lizards are autonomous, which means that they will shed their tail to escape capture. Be very careful picking them up. Lift them by placing your hand under the belly, never pick them up by the tail.
Sex determination can be extremely difficult in this species, since the males closely resemble the females throughout most of the year. The easiest time to differentiate between the sexes of these lizards is during breeding season, during which time the colors of the males intensify and the throat becomes a brighter orange and facial color variations may occur. The males also exhibit an increase in intraspecific aggression at this time and should be kept separated from each other. Females, on the other hand, tend to maintain the typical brownish body coloration throughout the year, although some may display a slight tinge of yellow or orange along their jaws or sides.
The yellow throated plated lizard is an opportunistic omnivore, but it gains the majority of its nutrition from insect material. Other items that make up small portions of the diet may be small pinkie mice or plant material. Since the lizard is indigenous to a semi-desert environment, fruits and vegetables are often consumed to supplement the water intake of the lizard. Collard greens and mustard greens are also excellent sources of vitamins and serve as ideal forage for the lizards. Lizards should be fed every other day; the amount will vary from lizard to lizard. If insects are offered as an exclusive food source, a vitamin supplement must be used. The insects should be dusted with the vitamin supplement at every feeding when the lizard is young and growing, but may eventually be cut back to every other feeding after they reach their adult size. A medium sized bowl of water should also be provided daily.
Members of the Suborder Serpentes, or the snakes, are the easiest to house and care for. Among the snakes that will do well in the classroom in ten or twenty-gallon vivaria are the common boa constrictor, the red rat snake or corn snake, and the yellow rat snake. The same physical set-up used for the lizards will do nicely. However, there should also be a rock or some rough object such as a portion of a brick to aid the snake in shedding its skin. If the snake is arboreal, a small branch cluster for climbing is highly desirable. However, do not place sand or earth in the tank, instead use newspaper or paper toweling. Sand and earth provide shelter for many harmful parasites
of the snake. Adjust the temperature in the vivarium to correspond to the temperature of the snake’s native habitat. So, for instance, you should keep a boa constrictor at about 30°C (86°F) and a black rat snake at about 23°C (73°F).
All snakes are carnivorous and most of them refuse anything but live food, so you should plan on feeding them live mice, rats, worms, insects, frogs, toads, and even other snakes, depending on the species being kept. Make sure to research the habits and environment
of any snake you bring into the classroom. The snakes will need to be fed every week or every other week, depending on activity. A hungry snake will be very active in search of food and will be a very recognizable sign after some experience working with these animals.
The remaining order of Reptilia, the Chelonia, does the best of all in the classroom. Turtles that do very well in a ten or twenty-gallon aquarium tank are the red-eared slider (commonly sold by pet shops), map, and wood turtles. Some native soft-shelled turtles will also prosper in a watery environment. The tank should contain 4 –5″ of water. There must be several rocks in the water to allow the turtles to sun themselves out of the water. Turtles placed out of natural sunlight will need a minimum of five hours a day under ultraviolet light. Turtles also need calcium for proper bone and shell development. Calcium may be provided through a plaster-of-Paris block placed in their water, or it may be provided by sprinkling the food with bone dust. Their diet should be varied and may include stewing beef, beef heart, smelt, shrimp, cheese, hard-boiled eggs, and occasionally lettuce.
Land tortoises may be maintained in a terrarium-type vivarium. The box turtle is best to keep in such an environment and will feed every other day on such things as berries, lettuce, tomatoes, dog food, and even peanut butter. You will need to discover, through trial and error, the right combination for each particular turtle. These turtles will also need ultraviolet light and a water bowl placed in the enclosure.
It is easy to see that the proper care and housing of reptiles, while somewhat complex, is still much simpler than that required for many mammals. Reptiles have very little odor and the vivarium is easily cleaned by removing and renewing the newspaper. Reptiles all have a relatively low metabolic rate and can live from several days to weeks without food if they are healthy. This means that they do not have to be taken home on weekends and holidays. Live reptiles are readily available from WARD’S and pet stores. They may also be captured locally in many places.
This guide is also available in PDF format at wardsci.com.
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To test for starch, remove the covered leaf and one of the others. To remove the chlorophyll, which would interfere with the color test, place the leaves in a beaker half filled with alcohol. Place the beaker in a water bath (a larger beaker partially filled with water will be suitable) and boil over a hot plate until the leaves become blanched. Do not use a Bunsen burner or other open flame as the fumes of alcohol are highly flammable. When the leaves are blanched, rinse well in water and place on the bottom of a Petri dish. Cover with Lugol’s iodine solution (dissolve 10 g of KI in 100 ml of distilled water, add 5 g of iodine) and leave until darkening is complete. Rinse off the iodine solution and view against a white background. The presence of blackish areas indicates starch.
