Reptiles are cold-blooded vertebrates. They breathe air by means of lungs at all stages of life. They either lay eggs or give birth to living young. Egg-laying species must lay their eggs on land, although many spend a considerable part of their lives in the water. They require fairly high temperatures to remain active and species which live in temperate countries must hibernate during the winter. Virtually all major groups of reptiles contain some endangered species. There are also national and international conservation regulations to be considered when choosing reptiles for study or captivity. Reptiles are commonly used for anatomical and comparative physiological studies.
Snakes can be identified by tattooing, branding and clipping of the caudal scales. Lizards can be toe clipped or painted. Tortoises and turtles can be identified by notches on the carapace and plastron, grinding or filing the carapace, toe clip (young specimens) and aluminum tags with permanently embossed numbers. Temporary identification can be accomplished with adhesive tape strips or polish placed on the shell.
Handling and Restraint
Reptiles should be moved gently, confidently and quickly. A hesitant or jerky approach often promotes a bite. If handled repeatedly and gently most reptiles can become less aggressive. Many reptiles can be scooped up by the body and moved quickly with no real restraint needed. When restraint of the head is necessary the body and legs should be supported comfortably to prevent thrashing about that can lead to injury. The hook is an effective tool for lifting a snake. It is slid under the snake one-third to midway down the body. The snake should then be lifted quickly about a meter or so above other surfaces.
If handling snakes with hands it is important to support the body comfortably. Snakes can be immobilized for exam by inducing them to enter a transparent tube. Holes can be cut into the tube for access. Highly venomous snakes and lizards should be handled as little as possible and kept in locked cages. Large lizards can be held by grasping the head with one hand and pinning their front legs against the body and grasping the hind legs pinned against the tail with the other hand. Small lizards should not be enclosed by a hand for more than a few seconds since this may injure or kill them. Lizards should not be handled by the tail alone since this may injure them. Turtles can be picked up by the shell. Snapping turtles and soft-shell turtles should be carried only by the tail and held well away from the body. It is best to wear protective gloves when carrying them. The heat of a lamp may cause a spontaneous relaxation of turtles which may cause their head to extrude from the shell.
Cyclical activities, such as mating, skin-shedding, and hibernation are likely to be disrupted in captivity. Also, many reptiles in the wild show territorial behavior during the breeding season and this may be inhibited in the laboratory. In captivity they are liable to become sluggish and refuse to feed. They may not breed in the lab. It is best to keep species separately and to keep the number of each species within a primary closure to a minimum. Most diurnal (active during the day) reptiles like to bask in sunlight. A sunlamp can be used for this purpose and should be left on for a daily period appropriate to the need of the species. Cage temperature should be appropriate for the species. All reptiles periodically shed their skin. How completely and intact as well as how often a reptile sheds is a health indicator. A healthy animal that is eating and growing sheds more frequently. Lizards, turtles and crocodilians shed in many pieces. Snakes normally shed in one piece from nose to tail. Sickness or inadequate humidity may cause a reptile that normally sheds an intact skin to shed in pieces or to be unable to shed. In the latter case placing a snake in a bowl of warm water can assist the shed.
Any changes from a reptile’s natural environment can cause stress such as excess handling, inadequate temperature or humidity, improper lighting, overcrowding, damp or unsanitary conditions and lack of a hiding pace. Adaptation periods can vary between species. Stressed animals may refuse to eat and can starve to death. Once a reptile is eating in captivity and is not unduly stressed it is an indication that it has adapted.
Lighting should be correlated to a reptile’s natural circadian rhythm. Wide-spectrum fluorescent light tubes are recommended for lighting.
Reptiles are ectothermic so their body temperature tends to be that of their surroundings. For species such as snakes, providing appropriate constant ambient temperature is adequate. For turtles and lizards it is best to establish cage conditions that allow reptiles to thermoregulate. This can be done by providing a thermal gradient using a heat source in the form of a light bulb at one end of the cage and an escape from that radiation in a shade of hide box at the other end. Daily fluctuation in temperature is critical to turtles and lizards feeding mechanism.
Hiding places in cages is very important for all reptiles. Tree limbs, rocks, logs, artificial plants and water vessels all can be used to enhance the environment. These articles and cage substrates should be sanitized appropriately on a regular basis. Glass aquariums are a satisfactory means of housing reptiles. For many species the top can be covered by wire or a screen and should be securely fastened. Cage size is somewhat subjective with considerations of thermoregulation being most important. Snakes require a minimum of one square meter of animal length. Paper butchers wrap can be an ideal flooring material for reptile cages. Burrowing reptiles require sand or soil which can be substituted by natural gravel mixed with the soil or sand but must be replaced or washed frequently. The floor should be covered about 5 to 10 cm deep.
Most reptiles defecate two to three days after food intake. Cage cleaning should be scheduled accordingly and should not occur sooner as disturbances closer to feeding can cause the animals to refuse food or to regurgitate recently eaten food. A container of water must be provided but one should not assume that the reptile is drinking form it unless one actually witnesses it. Reptiles may soak in their water containers. Lizards will lap water from wetted leaves or from wetted cage surfaces. Daily misting is beneficial to many species if the cage is ventilated so the water can evaporate. A pan of shallow lukewarm water in which the snake can soak should be placed into the cage to help the snake to shed. Also, the presence of a rough-surfaced heavy object will help the snake shed its skin.
Snakes are carnivorous and swallow their prey whole. This can be accomplished since the snake’s uniquely articulated jaws and skull are quite pliable. Many captive reptiles, especially snakes, eat only live food. Snakes rely on movement and smell or stimuli to react to food. A live animal may be quickly seized due to its movement, and a dead or motionless animal detected by smell. Some will adapt to feeding on dead animals or parts of dead animals. These foods should be frozen prior to use to reduce the risk of contracting infection. The food should be completely thawed and warm enough to stimulate the reptiles into feeding. It is best to leave the animals alone after being fed.
Live rodents should not be left unattended with snakes as they could attack the snakes. Healthy snakes may do without food for several months without harm. A fast may sometimes be terminated by raising the temperature, by giving the snake a warm bath or by repeatedly presenting different types of food in various ways. Changing a snake to a new cage will sometimes stimulate it to begin feeding. Lizards should be offered a wide variety of foods and given a vitamin and mineral powder one to two times a week. They can be fed small meals every 24 hours or larger meals every 48 to 72 hours. The powder can be embedded in the food or put in the drinking water. Most lizards are insectivorous. These lizards must thermoregulate to achieve the proper body temperature to capture live prey. The type of insects given should be varied. Generally, feeding as much as the animal will eat two to three times a week maintains body weight and allows normal growth. Smaller species may need more food and larger species may need less food.
Large lizards are usually carnivorous. They can eat a diet of lean meat, raw eggs, rodents of the appropriate size, chicks and sometimes fishes. They do not need to have live food. A few lizard species are mainly herbivorous preferring leafy greens and soft fruits. Lettuce should be used sparingly since it has little nutritional value. Fresh water turtles in general, both aquatic and amphibious are carnivorous but do not necessarily require living food. They can feed on a variety of meat, fish and small animals. Some will eat green, leafy vegetation. These turtles must feed in water that is deep enough to allow them to submerge while swallowing. A calcium supplement is essential for all species fed boneless meat. Turtles tanks can be cleaned several hours after eating. Terrestrial turtles can be omnivorous or herbivorous. Lowfat dogfood can be a good substitute in moderation for red meat. It is more nutritionally complete and has a more favorable calcium to phosphorus ratio. Turtles can be fed small meals every 24 hours or larger meals every 48 to 72 hours.
The male snake has paired hemipens recessed into a diverticulum caudal to the cloaca. The sex can be determined by inserting a probe into the diverticulum. In the male the probe can be inserted to a considerable depth whereas in the female the probe can only be inserted approximately 1/4 inch. In some species a difference between the sexes is evident in the form and number of ventral scales, the male having fewer abdominal and subcaudal scales. The male body is relatively shorter than that of the female. Male snakes have relatively longer tails, and the tail base is wider. The male lizard is commonly larger and tends to have more differentiated dorsal or caudal crests. Male lizards also have larger, broader heads. Male turtles have a longer, thicker tail than females. Males have enlarged scale on the tail tip or long claws on the front feet to clasp the female in copulation. The plastron may be more concave to help the male retain balance on the convex carapace of the female.
Refer to the Table below for bleeding sites for reptiles.
|Some Bleeding Sites for Laboratory Reptiles|
Ant. vena cava
|X -- usually larger ones||X -- usually larger ones||X -- except marine Galapagos and albabra ones||X -- larger ones|
|Caudal Vein||--||X -- ventral caudal spinal vein||--||X -- larger ones|
|Toe Clip||--||X -- small amount||X -- small amount||X -- small amount|
|Jugular||--||--||X -- larger ones||X -- larger ones|