Species Endangered (MS-Blog Series from) IX / 09

(The) Gila-Monster

Class: Reptile

Order: Squamata

Latin name: Heloderm heloderm

Range: SW(South-West) US / NW (North-West) Mexico (Sonora deserts)

IUCN Status: NT (Near Threatened) ; though, they're mentioned to almost 'qualify' for the VU (Vulnerable) classification /Cites: Appendix I

(2009 situation)

From the variety of lizards in the world, we've selected to our series a rarer example, the venomous Gila-monster (Heloderm heloderm). It being one from only two venomous lizards and therefore actually an oddity, that surprising or even strange - but the other venomous species also inhabits Sonora desert, its (Mexican) beaded lizard (Heloderma horriblis, LC) (Together these make separate a sub-group of their own, Helodermatidae). As the Gilas are culturally rather multiform from beliefs and tales, also mentioned in this connection its names in few other languages (in French, Lézard Perlé and, Spanish Monstruo de Gila) (From Gila-pics, see fx the links at the end of text, they also contain more species specific information than is presented here).

From (false) Gila-myths and circumvented stories there is fx the popular belief from this lizard being capable to jump for an attack. Also – according to Dr Sewards Gila-pages – they've in the past (unjustified) fx been believed able to poison with their unhealthy, rotten smelling 'Gila-breath', and, also 'their bite being impossible to break off' (~won't let go until dawn of the day !). Both are only superstition and Gila's only move slowly on the ground, but actually they do bite hard if harmed. Having no Gila's close my headquarters, I've only encountered them in the comics, which actually gave me (actual) reason and interest for this example – but this mentioned only as example from these (Gila-)myths, typical of those, I suppose; In the Charlier-Giraud book from the adventures of lt (Mike) Blueberry (The Lost Dutchman's Mine^1.) the old gold-digger/traitor finds himself trapped in pueblo housing and when searching for drink there's only a bowl of water where floats a dead Gila-monster...(Quite obviously any animal carcass in the boiling desert sun and heat spoils the water, but this only mentioned as typical example from intentional use of the lizards bad reputation.)

In this part on our series we don't possibly have space lengthy histories/stories from lizards (lacertilia) and/or reptiles evolution, but few perhaps can briefly be mentioned (as some comparison, though there seems to be apparently hundreds species their various genera and the relatins not always too clear, perhaps.). The sub-order Squamata, (according to information we find) contains basically lizards and snakes species with overlapping scales. Includes the 'modern lizards' generally, but also from evolutionary more distant origin still is extant Tuatara (Sphenodon punctatus, separated for its own genus/group and the sole member in it). Mentioned Tuatara(s) survive today only in New Zealand islands and is considered a 'living fossil' even among reptiles (it even has 'false' 3^rd eye on its forehead, sometimes assumed a remnant from early evolutionary experiments in the development of vision) Also, Tuatara is supposed to originate from about 180 M years to the past. In parallel with its (supposedly) 'ancestral' preceding species/earliest lizards also evolved the Archosaurs, which in their time gave rise for various other animal groups including crocodilians and dinosaurs (and from latter then subsequently evolved the birds, according to current theories and beliefs).

But, briefly the modern groups of lizards and snakes are known to have later evolved for their own path from the lizards 'base group', Lepidosaurs (from which, apparently earlier, separated a different lineage reaching for the extant Tuatara). Among the various lizards suborder(s), we find currently at least extant clans of the Iguania, Gekkota, Amphisbaenia ('worm lizards), Autarchoglossa ('skinks' and other varieties, including the snakes) – I guess they make the classfied main groups, at least supposedly it being so (But snakes fx also are usually excluded from lizard and classified as separate subordinate clan of their own). All the mentioned (lizard) groups actually contain rather various interesting peculiarities, (and more, like the Chameleons, that mostly appear in African forests...or, fx Galapagós-island endemic and particular species; Sea Iguanas?/Leguans (VU) fx, that are the only marine lizard species.) But, Anyway, various lizard genera (like Iguanas, and Gekkos especially) also are adapted to climbing on trees at tropical forests, and so the Iguanas are common in ranges from South America to Mexico and Caribbean islands (/and so appear inhabiting mainly the Central- and South American tropical forests.)

Lizards that perhaps somewhat more resemble the Gilas/Helodermatidae group are found from Varanidae or the 'monitor lizards' (at least, I suppose these are synomous category, if it not being that the other is a sub-group of the other...) like the Comodo Dragon (Varanus komodoensis, VU) – although geographically rather distant; It only inhabits restricted Comodo islands, and is largest of the extant lizards. They can reach about 2.5 m and weight almost 100 kg – Gila's for comparison, only are about 50-60 cm and weight some 4-5 kg that also being rather large for extant lizards (many that appear common in various parts of the world are only tens of centimeters in length. The small lizards are more typical of course, but basically also mostly carnivorous.) The Varanidae contain plenty more larger species, but, here no space for further observations... Strangely, but probably a result from its limited (current) range the Comodo dragon remained practically unknown to (science) all up until the early 20^th century. To the contrary Gilas have been known (for science) long time, at least since the 19^th century at least.

Gila Monsters deserted living environments would therefore perhaps feel a bit peculiar from this point-of-view. But, actually deserts offer a habitat for many lizard species – perhaps, it has something to do with their distant origin from the Reptilian ages (“When the Dinosaurs reigned the Earth” as goes that common paraphrase...). Because the Earthly climates Millions of years ago in the prehistory were lot warmer than today, the animals with changing body temperatures nowadays appear more commonly in places where there's hot and/or humid conditions, like rain forests and deserts – The lizards kind of made logical conclusions and selected the warmer regions as the global climates did coollen considerably after the K/T-boundary^2. , about 65 Million year ago). - But, it must be reminded, plenty extant reptile and lizard species also inhabit the more temperate regions, of course. Also noticed (here), that lizards are among the most abundant species on deserts (In fact, snakes are found more numerous, but lizards are more often seen since they are active in day-time and snakes mostly are nocturnal).

Even for the species that adapt their body temperatures for changes of air and ground warmth (like the reptiles), the deserts can be extreme environments; fx at Sahara in the hottest times of the day temperature can raise over the 50 C (in shade) and – to the contrary – in the night-time can be very cold since warmth of the day soon escapes for the open skies (As well, in the desert Gobi some -40 degrees Celsius night temperatures have been measured). In the hottest periods at the deserted environments even the lizards usually rest in the shades. Gila's particular districts merely consist from somewhat semi-arid environment it seems, they are found from scrubland, and other places with limited vegetation, and, oak woodland (fx). Like many species, they also spend certain season (winter) in hibernation (and we find it surviving over that period with the grease stored in its tail. Also the species actually predates and eats only handful of times in during the dry season when its actively 'awake'). Other periods, Gilas spend major part (95 per cent, it is mentioned) of their time hiding in the burrows, under rocks and covers, etc. So it is noticed being that lizards (like any species, but Gila's in this case) also are behaviorally adapted for their living environment (desert) and its conditions.


The poison of the Gilas, usually serves as a defence since it mainly hunts slowly moving animals, fx mammalian and reptiles eggs, smaller desert species, and carrion. Can eat other smaller reptiles too. The Gila's are immune for their own poison as are fx some amphibians species (from the reasons that are not especially clear, seems to be mentioned). Natural enemies Gila's don't have, that much powerful their venom is, fx its capable to kill rabbit easily and the larger desert species like coyote soon learn to avoid it.


It feels therefore quite easy understand the reasons causing their 'bad reputation' and that they've been (especially in the past) killed from the fear of species being venomous (although, according to dr Sewards pages there's no reliable accounts from human deaths having resulted from Gila bites and also they're basically slow in movement.) Anyway, for one not living in their particular districts it feels a bit surprising that more recently habitat loss from the uses of agriculture is mentioned as main threat for Gila Monster, but so is mentioned, as their favored living areas have been cleared from the way of cotton fields, fruits plants and human settlements. Far more typical feels the other main threat for Gilas; Like many comparable decorative looking lizards they are found illegally collected for the pet trade and private collections. (Although, it actually feels quite surprising that people would want to hold venomous animals as pets, even poison teeth removed. But, often these species are also pretty spectacular from appearance. Gila's, like many other species, are also raised on captivity and sold in the legal pet market).


There's of course various lizards that are collected/hunted for pets, but in this case we find also the past histories from the endangerment of various subspecies of Iguanas (Ground Iguanas/Leguans?). From these impressive lizards, some (often large species) were earlier such common in their isolated habitats at West-Indian Islands that shiploads of them were transported for US, and other places, causing some species endemic to islands disappear completely. (Another particularly harmful factor mentioned has been the introduction of the predative Indian Mongoose for their natural environments.) More recent times (fx the Green Iguanas, Iguana Iguana) has seen intensified raise on captive farming market at different countries in the South America and still exists apparently huge demand (some several hundreds of thousands of iguanas in single year at 1990s, sold at US solely). As the main downside, many animals also die as result of insufficient care (ao) in farms or the pet homes. From the Gila's we find that they've been protected species for some time, and (for their luck) there's also been breeding program of them since 1963 at San Diego Zoo.


Global trade of the (wild) animals is not limited for the lizards of course, and the methods/level of care probably a lot varies. Large part of the popular species sold in the pet shops originate from the South-Asian animal farms, but as well from elsewhere (mostly the tropical region). In fact, collector markets exist in the different parts of the world, and largely it's been noticed that often in the process of one single animal captured for the zoo/animal farm/lab/home many other may have been harmed/killed. Also many species that are favored from their peculiar and colourful looks or from other reasons aren't necessary very well adapted for life as pets.


Many bird species have been declined from collecting them (parrots, ao, and from the past histories, at the turn of the 19^th and 20^th century, fx the Birds of paradise species and Egrets feathers were largely collected – latter mainly for making of hats, former also for museum collections, etc.) Snakes probably make another most typical group (whose wild populations) may be generally harmed from pet trade. Concerns even aquarium fishes, though one would suppose most easy to successfully reproduce them in numbers without harming wild populations. (On the other hand, it can be mentioned that in some cases the establishment of legal market and pet farms may have helped save animals wild populations.) But, from that Beer-Morris book (often referred in these posts), we also find plenty more animal species, mainly/or partly endangered as result from the (illegal) trade of species and their collecting; fx Birdwing butterfly (Ornithoptera alexandrae, EN), Red-Kneed Tarantula (Euathlus smithi, NT) (- though it feels quite strange how a single Indiana Jones film might have 'created' the mass demand and largely increased Tarantula collecting, but so is mentioned), Golden Mantella (Mantella aurantiaca, CR), Egyptian Tortoise (Testudo kleinmanni, CR). In addition to these few examples, there's also various more - including plenty monkey species, etc.


So, we can in this case briefly finish this post by noticing this exemplary species, Gila-monster, probably having somewhat benefited from it's 'life-style', largely under covers/hides (and the early days of its being protected, and as well the mentioned captive-breeding program maintained in the zoos rather early, I suppose) - even if the species original habitat has been reducing, nowadays. For a funny part, from its appearances in movies, is mentioned (Wikipedia) also the existence of 50ies b-movie The Giant Gila Monster (among the worst in those, I kind of remember it having been...)

Notes:

1. Is the name of the 1990s repressed album, but if I remember that correct, this brief Gila appearance is only presented in the original 1970s version; redrawn albums slightly differ from detail and I cannot quite recollect original name of that earlier version.

2. With the K/T-boundary, we mean the Cretaceous-Tertiary edge when the global climates changed largely for colder environments (/the end of Mesozoic and begin of Cenozoic era) - And not the K/T – mass-extinction event or the possible cause/causes of it (like the Asteroid impact(s) ; Supernova / Increases of cosmic radiation ; or Vulcanic activity , that are nowadays usually stated as the most likely reasons that might have caused the Dinosarus disappearance from Earth in those distant times, ca 80-60 Million years ago... the first mentioned apparently nowadays the most generally accepted theory.)



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Main sources (/further [Gila-]information):

Beer-Morris (2005) : Encyclopedia of the Endangered Animals.

IUCN Red List (www.iucnredlist.org) – from Heloderm (heloderm)

San Diego Zoo's pages from Gila Monsters

Dr Seward's Gila-Pages