Reptiles have an amazing variety of behaviors. In captivity, some can be misinterpreted as signs of illness or injury.
When threatened, lizards may swallow air to increase their size, hiss, gape and lash with their tails. They also wriggle their tails to distract the predator and allow escape.
Those who do not seek shelter, hiss or display defensive aggression are likely stressed and should be evaluated by a veterinarian.
Defensive Displays
Reptiles use a variety of defense mechanisms, including camouflage and body armor. Many also make loud sounds to scare or confuse their predators. These sounds often involve the hissing of snakes, crocodilians and lizards. This sound is created by forcing air out of the lungs through a flap in the esophagus, which amplifies the hiss. The hiss of a veno 크레스티드게코 mous snake mimics the sound of its rattle, and this 크레스티드게코 may cause some predators to flee.
Even non-venomous snakes can look threatening in some circumstances, such as when a Gophersnake assumes a defensive posture to protect its young. The Gophersnake coils up, hisses loudly, and elevates its head and neck while shaking its tail. The California Kingsnake shown in the video below shakes its tail, which could be a behavior similar to a rattlesnake’s rattling or perhaps a warning signal that it has been spotted by a possible predator.
Many lizards also display a bad smell to deter predators, and some can detach their tails to distract them long enough to escape. Leopard geckos are especially adept at twiddling their tails to frighten predators. This behavior can continue for 30 minutes or more and can help the lizard distract the predator long enough to get away. Another defense mechanism is called “death feigning,” where a reptile acts as if it is dead, which can sometimes deter a predator from attacking.
Social Behavior
Although reptiles are often portrayed as sluggish creatures that live simple, asocial lives, many species engage in complex social behavior. It is well-known that many crocodilians have intricate courtship rituals and dominance hierarchies, and that some skinks form long-term monogamous relationships. It has also been found that some turtles spend a lot of time playing and that a number of snakes have specialized vocalizations that allow them to communicate with each other.
More recently, researchers have discovered that some reptiles, like the black rock skink, exhibit social behaviors that are reminiscent of more overtly social mammals and birds, such as territorial systems, nesting aggregations, and maternal care. In one study, the authors showed that this reptile, and several other related skinks, exhibit kin-based altruism, showing that these animals recognize their own relatives.
It is unclear if this kin-based altruism helps the snakes to avoid predation, but it is certainly interesting that it does so. Further research on these fascinating animals may reveal new information about how they communicate with each other, and also how the environment can impact their behavioural traits. For example, studies of other species of birds have shown that social isolation reduces the ability of a songbird to produce and process the complex songs that characterize their species. It is possible that the same applies to these lizards, and that they can only successfully reproduce in groups.
Egg-Laying Behavior
The clustered temporal pattern of egg-laying behavior in C. elegans has been mathematically described as a Poisson process with two time constants and a switching probability. However, the behavioral evidence suggests that this model is not only too simple but also provides a very incomplete picture of the circuitry underlying egg-laying.
Recent work has revealed that the clustered temporal pattern of egg-laying is governed by the interaction between two pairs of neurons. The HSN neurons are the command neurons of the circuit; each autonomous Ca2+ transient in HSN can activate vulval muscle cells (vm1 and vm2) to produce one egg-laying event. In addition, HSNs are modulated by VC neurons, and integrate environmentally controlled neuromodulatory signals that influence egg-laying frequency.
Using optogenetic activation of the VC neurons, we have found that the phasing of Ca2+ transients in vulval muscle cells correlates with the timing of the corresponding egg-laying events. These observations are consistent with the hypothesis that acetylcholine released from VCs slows locomotion during egg release, and that this contraction elicits the behavioral response observed.
We have also discovered that uv1 neuroendocrine cells sense the passage of eggs through the vulva and release tyramine, which inhibits HSN activity and egg-laying. In ocr-2(vs29) animals, which have lost their ability to make tyramine, we have found that the residual twitch transients in vulval muscles exhibited a phasing identical to those in the non-egg-laying active state. These data suggest that the uv1 cells might provide long term silencing of HSN activity and egg-laying behavior by inhibiting HSNs with an inhibitory neurohormone, similar to how they inhibit other cell types in the body.
Aggression and Dominance
Aggression is a common part of reptilian life and can be directed at conspecifics, other species, or humans. It may be overt as physical attacks requiring significant energy expenditure and risk of injury or more subtle as bluffs, displays of dominance, and chemical cues. Overt aggression is often rewarded by social group dominance hierarchies, and behavioral traits such as aggressiveness have been found to be associated with both the strength of dominant males and their overall body size.
Defense behaviors include blood spurting best known in horned lizards, tail displays including waving and caudal autotomy (tail shedding), rolling into a ball as demonstrated by royal (ball) pythons, retraction of the head into the shell as shown by chelonians, and death displays such as turning upside down and releasing a foul odor that mimics death as observed by eastern hognose snakes. It is important for the veterinarian to consider any exhibited behavior when assessing a reptile’s health and well being.
In captivity, aggression between tortoises frequently occurs and can result in the ejection of one tortoise from the group, the submission of one tortoise to another, or even biting. This can result in severe injuries, infection, and possibly death. Several studies have shown that captive reptiles will develop temporally stable dominance hierarchies and that this results in reduced frequency of aggressive interactions.