Familiar Perentie

Familiar Perentie
Image from Luke Campbell


The familiar perentie is a popular reptilian pet dating back to pre-Technocalypse Earth, descended from monitor lizards. It has expanded with humanity to the stars, typically fulfilling a role as a pest-control predator or a companion animal. The clade has diversified to many different breeds, including a number of provolve lines.


The familiar perentie is a large and powerful lizard. Various breeds will range in size from 30 cm to 6 meters as adults, but the ancestral stock was typically mature at 1 meter and reached 1.5 to 2 meters at maximum size. Their appearance is striking, with a bold pattern of spots, stripes, and reticulations over a lighter background. Pebbly skin hangs in loose folds about its neck and body. The body is powerfully built, with massive legs ending in thick, curved talons. A triangular head filled with sharp, flesh tearing teeth is held aloft by a thick but elongated neck. The throat can be greatly distended to bolt huge chunks of meat or warn off adversaries. The eyes are bright and alert, while a long forked tongue flickers in and out of the powerful jaws when the perentie is on the move, or just interested or excited. The tail is long and muscular, flattened from side to side and flexible almost to the point of prehensileness.
The perentie walks with a confident and swaggering gait, holding its massive body well clear of the ground with only the feet and tip of the tail touching the earth when moving.


Familiar perenties have an uncanny sense of smell. It is their primary means of identification. They also use it to track prey, locate prey (even prey buried some distance underground), and keep tabs on the other local perenties. They do not smell by inhaling air through the nostrils, rather they flick their tongues out. This picks up odor chemicals from the air or surface of whatever the tongue touches. When the tongue is withdrawn, the odors are conveyed to a sensitive chemosensory organ on the roof of the mouth. The tongue is forked, by sensing which fork has a stronger concentration of odors, the perentie can follow scent gradients.

Perenties have acute vision, but their ability to recognize objects by sight is limited. Rather, they rely on vision to detect moving prey and to avoid threats, with most identification performed via smell. Perentie vision is tetrachromatic, with four primary colors of red, green, blue, and UV-A. It is adapted to work best in daylight - they have poor vision at night. Some perentie breeds and most provolve lines show enhanced ability for visual discrimination, but this is not common among pet and working varieties and usually comes at the expense of chemosensory acuity. Their visual recognition is, however, notably improved over that of their monitor ancestors, such that an owner does not need to worry about his pet failing to distinguish between his hand and the food he is holding.

The hearing of familiar perenties is improved over that of baseline monitor lizards, but they still do not have much sensitivity at higher pitches and many have trouble distinguishing between spoken works. Those kept as pets are best trained by hand signals or simple audial cues (such as clickers or whistles).


Perenties primarily communicate with other perenties by leaving scent marks. They have pheromone glands on their chins and necks and on the base of their tails which they use to mark territory and advertise for mates. The social scent signals are sufficient to communicate sex, maturity, and overall fitness. The most common perentie provolves use scent-based languages.

Perenties make use of a considerable range of postural communication. Anxious perenties distend their throat and arch their neck, as they become more frightened they will stand up tall and flatten their bodies toward their antagonist while cocking and coiling their tail in preparation for a whip-strike. When aggressive, they will approach slowly from a tall stance and lowered head, twitching their heads back and forth. Tactile communication is evident as affectionate head rubbing. Most perenties enjoy having their head, neck, and back scratched or rubbed, particularly around the ears.

A frightened or angry perentie will emit a very loud hiss to intimidate its rival or antagonist. Lower volume hisses sometimes accompany frustration or mild anxiety.


Perenties are swift runners over short distances. They can outdistance a baseline for several hundred meters before tiring. At high speeds, they may occasionally run bipedally for some distance. Perenties also have considerable aerobic walking endurance, enabling them to cover large areas of land while

Familiar perenties commonly stand erect on their hind legs, bracing themselves with their tail, in order to view the world from a higher vantage point. This is most commonly observed when the perentie is in a cluttered environment and wishes to see over obstructions.

Perenties are powerful and skilled swimmers. Their sinuous bodies and muscular, laterally flattened tails enable them to rapidly propel themselves through the water. The low basal metabolic rate enables a perentie to remain underwater for up to an hour before surfacing to breathe.

Familiar perenties are agile climbers. They can scale vertical cliffs, rock faces, and trees. Their claws can find purchase on minor irregularities, and they are muscular enough to friction-clamp to smooth poles or chimney up cracks.

Perenties are powerful diggers. With strong forelimbs and large claws, they can rip through hardened dirt and shovel it out of the way. Bored perenties have been known to tunnel through drywall or rip apart metal mesh.

When performing exercise, a perentie will use its muscular throat pouch as a pump to inflate its lungs with air. This aids in breathing and allows these lizards to maintain prolonged periods of aerobic activity. Consequently, an active perentie will be observed to make frequent "gulping" motions with its

Diet and Hunting Behavior

Perenties are hunters and scavengers. Opportunists, they devour any food they can find with a ravenous and often messy enthusiasm. Live prey is grabbed with the mouth, pinned to the ground by the perentie's weight, and killed by vigorous thrashing and ripping with the claws (although prey which is too small to effectively fight back may be swallowed while still alive). Larger victims may be crippled first by attacking the limbs or by traumatic blood loss from multiple lacerations, and killed by ripping out the intestines. All perenties are fond of eggs, and are notorious nest raiders. Perenties locate much of their food with their acute sense of smell. They will track injured or sick game, find and dig up burrowing animals, buried eggs and corpses, and can smell a rotting carcass from kilometers away. Perenties often hunt from ambush, bursting from cover to catch their quarry by surprise. They can also be opportunistic and active foragers, ranging widely to locate food to fuel their activity, criss-crossing to pick up scent trails of likely quarry. Large prey is ripped apart messily with teeth, vigorous thrashing, and raking with the claws. Remarkably large chunks will be bolted down. Smaller prey is generally eaten in once piece, either crammed into their gaping maws or thrown down the gullet with a series of backward head tosses. Perenties will gorge themselves until bloated, and then lie in the sun to sleep off their meal.

Perentie saliva has mild toxic properties. It is an anti-coagulant and vasodialator. When combined with the wounds left by a perentie's teeth, this contributes to hypovolemic shock in a bite victim, both through blood loss and blood pooling in the extremities away from vital organs. Other toxins cause an immediate and often incapacitating sense of pain. Bacteria present in the perentie's mouth can also lead to sepsis if the wound is not dealt with promptly. The degree of saliva toxicity varies among breeds - some guard breeds have particularly venomous bites, while breeds intended solely for companionship may have negligible salivary toxicity.

Perenties kept as pets that do not have the opportunity to hunt vertebrate prey may suffer nutritional deficiencies when fed table scraps or common commercial foods made for mammalian predators. Where perenties are common, commercial foods will typically be available that are formulated specifically to provide a complete diet for these lizards. Alternately, many owners will feed whole vertebrate food items to maintain their pet's health. These do not need to be fed live food, perenties will happily accept pre-killed or frozen-thawed food items.

Social Behavior

Familiar perenties are more tolerant of their own kind than their wild ancestors. They quickly get to know their neighbors and those with whom they share a home range. Perenties react to each other as individuals - a given perentie will commonly tolerate some of those they know, act affectionately toward and prefer to spend time with other perenties, avoid yet others, and act aggressively towards some. While they do not form cohesive groups or packs, they do form a network of allied and trusted individuals. Those who are not part of the alliance will be met with suspicion or driven away.

Mating typically occurs only between allied individuals. Fertile females advertise their status by scent marking. If the female has several suitors, they may wrestle with each other to establish who has breeding rights. The victorious male will court the female by following her, rubbing his head and
neck on her body, and scratching his claws along her back. They will mate repeatedly over the course of several days until the female is no longer receptive, at which time they go their separate ways.

A gravid female will dig a nest in a location that provides adequate temperature and humidity for egg development. After depositing her eggs, she will commonly remain nearby to guard the nest from predators. This may include non-allied perenties, who would likely eat the eggs. When the young hatch, the hatchlings stay together in a group for the first several months of their lives. During this time, they are introduced to and included in the mother's ally network.

Agonistic behavior commonly starts with an aggressive approach, evidenced by a high walk, side-to-side head twitching, and hissing. If one party does not flee, they will commonly come together and engage in ritual combat. Both individuals will rear up on their hind legs and grip each other with their forelegs. They will wrestle in this fashion, pushing and twisting, with the seeming objective to topple their opponent and pin it to the ground. When one opponent has been bested, it will usually flee the area. Biting is rare in these contests, and usually occurs when a defeated individual cannot leave. Exceptions occur when one perentie is much larger than the other, which often results in cannibalism.

Perentie wrestling is an accepted sporting event on many worlds. Contenders are introduced and allowed to fight until one achieves dominance. Typically, the animals are separated at this time to prevent injury. This practice has led to specialized wresting breeds. In some jurisdictions, organized animal sporting events such as this are considered cruel and banned.

Environmental Requirements

Familiar perenties thrive in tropical and temperate climates. They do well in domestic settings, provided they have access to radiant light for basking and have a "hide box" that acts as a substitute burrow to provide a constant comfortable temperature, high humidity, and a sense of security. Care should be taken that the hide box is not too roomy - perenties feel most secure when they can feel the sides of their "burrow" pressing against them. If this need is not met, owners may discover their pet has slithered into a tight and nearly inaccessible (and possibly dangerous) part of the house.

Feral perentie populations are often present where they are kept as pets. Familiar perenties have proven more adaptable than their wild ancestors, and can survive and even thrive in a wide range of environments so long as they can find or dig shelter. They adapt well to urban areas, and many cities have feral groups of perenties that scavenge garbage and prey on smaller urban animals. When not intended as part of an ecosystem, introduced perenties can cause environmental problems by competing with local predators and preying on small to medium sized natives. Their habits of egg predation can be particularly problematic when the local egg layers have not adapted to monitor lizards.

Perenties are active reptiles with a large home range. In captivity, they can become destructive or neurotic if confined in small enclosures. It is recommended that perentie owners allow their pets to roam across much of the house. On planets where perenties can survive outdoors, allowing pet perenties outside is often controversial - mortality of indoor/outdoor perenties is higher than those kept inside, these perenties are exposed to more diseases and pathogens, and they will kill and eat a large number of native animals such as songbirds which may pose conservation issues.


Baseline monitor lizards are unusual among reptiles for their capacity for sustained activity and high intelligence. In their natural environments, they are fast, agile, and powerful predators that occupy the same niches as foxes and wildcats in more temperate climes. However, their reliance on external source of heat to raise their body temperature to a temperature of 32 to 40 degrees Celsius for optimum activity restricts their range to tropical environments, even though it allows them to subsist on much less food than an equivalent sized mammal or bird.

These traits led to monitor lizard being the first subjects of retemorphic gengineering - the practice of adding counter-current heat exchange blood vessels around core organs for superior heat retention in cooler climates. Un-modified monitors were difficult to keep in captivity because of their high heat requirements, not to mention their destructive nature and impossibility of toilet training. The first subject was the perentie monitor, Varanus giganteus, a 1 to 2 meter long predator from the desert regions of Earth's continent Australia. The wild perenties were fast moving, wary animals that subsisted on a diet of lizards, venomous snakes, rabbits, and kangaroos. In addition to retemorphing, the perentie was genetically engineered to be more trusting and tractable, less prone to destroying household property, more accepting and less predatory toward their own kind, and to defecate in specific toilet areas. The arid-land adaptations of the wild perentie helped to prevent kidney damage in the typically dry climates of baseline human houses.

Several generations were required to finalize the design, but the end result was the familiar perentie. This large lizard proved docile and even affectionate toward humans, hardy in captivity, well behaved indoors, and capable of thriving in an outdoor urban environment yet returning home for food, shelter, and companionship. The first familiar perenties were produced in the Interplanetary Age. They quickly became popular pets, ideal for those desiring companionship in the tight confines of increasingly crowded urban life. Soon, there were many different breeds of familiar perenties, from six meter guard-dragons to thirty centimeter pocket pets. Many were taken off-world, where their reduced feeding requirements compared to the (at the time) traditional feline and canine pets were significant selling points.

During the Technocalypse, the perenties adapted well to the protective enclaves and arcologies into which humanity retreated. They became useful for pest control around greenhouses and culture vats, although due to their predatory nature they would cause problems if they got loose in pens for farming small livestock. Due to their close mutualistic association with humans, they were brought to the stars in significant quantities during the great expulsion. Today they may be found as companion animals on most biont friendly worlds.
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Development Notes
Text by Luke Campbell
Initially published on 21 June 2010.