Lizards can endure surprising periods without food, a trait that counters the common assumption of their constant need for sustenance. These reptiles demonstrate remarkable resilience, with the precise duration they can survive without eating being highly variable. This adaptability allows them to persist in environments where food availability fluctuates.
Key Factors Determining Fasting Survival
The length of time a lizard can survive without food is influenced by several interconnected factors, making a single answer difficult. Species plays a significant role; larger lizards like iguanas often have greater energy reserves and can fast longer than smaller geckos. For instance, a small gecko might only survive a week, while a larger iguana could potentially last a month or more. Adult bearded dragons can reportedly survive up to three weeks, and leopard geckos over a month.
A lizard’s age, overall health, and existing body fat reserves also contribute to its fasting ability. Younger lizards generally have fewer fat stores and may face health problems after only a few days without food. Healthy adults with ample fat reserves can endure weeks or even months.
Environmental temperature is another major determinant. In cooler conditions, their metabolism slows, reducing energy demands and extending survival. Conversely, warmer temperatures increase their metabolic rate, requiring more frequent feeding. Hydration is equally important; a lizard might last weeks without food, but only a few days without water before succumbing to dehydration.
Biological Mechanisms of Extended Fasting
Lizards are ectothermic, often called “cold-blooded,” a characteristic fundamental to their ability to endure food scarcity. Unlike mammals and birds that maintain a constant internal body temperature through high metabolic rates, lizards rely on external heat sources to regulate their body temperature. This reliance allows them to significantly reduce their metabolic processes, a phenomenon known as metabolic depression, when conditions are unfavorable or food is scarce.
Metabolic depression enables lizards to conserve energy by slowing various bodily functions, including oxygen consumption and heart rate. This adaptation is particularly beneficial in environments with unpredictable food resources, allowing them to use far less energy than similarly sized endotherms. During these periods, their bodies efficiently utilize stored energy, primarily fat reserves accumulated in areas like their tails. Brumation, a state of dormancy akin to hibernation in mammals, is an extreme example of this metabolic slowing. Lizards naturally fast for weeks or months during brumation in response to cold temperatures, experiencing minimal weight loss due to their drastically reduced metabolic rate.
When Your Pet Lizard Isn’t Eating
A pet lizard’s refusal to eat can cause concern for owners, but it is not always a sign of serious illness. Normal physiological changes can lead to temporary appetite loss. For instance, many lizards eat less or stop eating entirely during shedding cycles, breeding periods, or when entering brumation due to seasonal changes. Stress from a new environment, excessive handling, or a new tank mate can also temporarily suppress a lizard’s appetite.
Persistent appetite loss, especially when accompanied by other symptoms, warrants closer attention. Signs that may indicate a more serious issue include significant weight loss, lethargy, sunken eyes, or changes in droppings. A veterinarian should be consulted if a lizard exhibits these signs or if its appetite loss is prolonged. Common husbandry problems often contribute to appetite loss, such as incorrect temperature or humidity levels, an improper diet, or an inadequate enclosure size. If environmental conditions are not within the lizard’s preferred optimal temperature zone, digestion can be impaired, leading to a refusal to eat.