وحش هيلا Gila monster
Conservation status
Near Threatened (IUCN 3.1)
التصنيف الفهمي
مملكة:	الحيوانية
Phylum:	الحبليات
Class:	الزواحف
Order:	حرشفيات
Superfamily:	Varanoidea
Family:	Helodermatidae
Genus:	'Heloderma'
Species:	''H. suspectum''
Binomial name
Heloderma suspectum كوپ، 1869
H. s. suspectum – Reticulated Gila monster H. s. cinctum – Banded Gila monster

وحش هيلا Gila monster (Heloderma suspectum, // )، هونوع من السحالي السامة موطنه الأصلي جنوب غرب الولايات المتحدة وولاية سونورا شمال غرب المكسيك. وهي سحلية ثقيلة الوزن، بطيئة الحركة، يصل طولها إلى 60 سم، وهي السحلية السامة الوحيدة التي موطنها الأصلي الولايات المتحدة وواحدة من نوعين من السحالي السامة في أمريكا الشمالية، والنوع الآخر قريب الصلة من beaded lizard المكسيكية (H. horridum). على الرغم من أنها سحلية سامة، فإن حركتها البطئية يجعلها لا تشكل خطراً كبيرا على البشر. ورغم حتى وحش هيلا من الحيوانات المثيرة للذعر وسبق حتى تسببت في حوادث اغتال للبشر، فهي محمية حسب قانون الولاية في أريزونا ونڤادا.

السمية

الانتشار والموئل

فهم البيئة

النظام الغذائي

يتغذى وحش هيلا على الطيور الصغيرة، الثدييات، الضفادع، السحالي، الحشرات والجيفة. ويعتبر بيضة (أحياء)بيض الطيور والسحالي هوالغذاء الأساسي لوحش هيلا، ويتغذى وحش هيلا خمس مرات فقط في السنة، وعندما يحدث ذلك فإنه يأكل حوالي ثلث حجمه من الطعام.ويستخدم وحش هيلا حاشة الشم القوية لديه في التعهد على الغذاء وخاصة البيض. ويمكنه العثور على البيض والحفر لعمق 15 سم تحت سطح الأرض للوصول لغذائه.

الزعاف

Venom is produced in modified salivary glands in the Gila monster's lower jaw, unlike snakes, whose venom is produced in the upper jaw. The Gila monster lacks the musculature to forcibly inject the venom; instead, the venom is propelled from the gland to the tooth by chewing. Capillary action brings the venom out of the tooth and into the victim. The teeth are loosely anchored, which allows them to be broken off and replaced throughout life. Gila monsters have been observed to flip over while biting the victim, presumably to aid the flow of the venom into the wound. Because the Gila monster's prey consists mainly of eggs, small animals, and otherwise "helpless" prey, it is thought that the Gila monster's venom evolved for defensive rather than for hunting use. A defensive use would explain the Gila monster's bright warning coloration.

Although the venom is a neurotoxin as toxic as that of a Coral Snake, H. suspectum produces only small amounts. The Gila monster's bite is normally not fatal to adult humans. There are no confirmed reports of fatalities after 1939, and those prior to that year are suspect due to the primitive dangerous "treatments." The Gila monster can bite quickly (especially by swinging its head sideways) and hold on tenaciously and painfully. If bitten, the victim may need to fully submerge the attacking lizard in water to break free from its bite. Symptoms of the bite include excruciating الألم، وذمة, and weakness associated with a rapid drop in ضغط الدم. تم فصل عشرات الپيپتيدات والپرويتنات من زعاف وحش هيلا، منها hyaluronidase]], سروتونين, phospholipase A₂, and several kallikrein-like glycoproteins responsible for the pain and edema caused by a bite. Four potentially lethal toxins have been isolated from the Gila monster's venom, including horridum venom, which causes hemorrhage in internal organs and exophthalmos (bulging of the eyes)[1], and helothermine, which causes lethargy, partial paralysis of the limbs, and hypothermia in rats. However, the constituents most focused on are the bioactive peptides, including helodermin, helospectin, exendin-3, and exendin-4. Most are similar in form to الببتيد المعوي الفعال وعائيا (VIP), which relaxes smooth muscle and regulates الماء وكهرل secretion between the الأمعاء الدقيقة والغليظة. These bioactive peptides are able to bind to VIP receptors in many different human tissues. One of these, helodermin, قد تبين أنها تحد من انتشار سرطان الرئة.

الأبحاث الدوائية

في 2005، صدقت ادارة الغذاء والدواء على عقار exenatide (يعهد باسم بايتا Byetta) لعلاج سكري النمط الثاني. وهوبروتين صناعي، exendin-4، يحضر من لعاب وحش هيلا. في دراسة أجريت لمدة ثلاث سنوات على أشخاص مصابون بسكري النمط الثاني، ثبت حتى عقار exenatide يحافظ على مستويات اگلوكوز الصحية ويساعد على تخفيض الوزن. The effectiveness is due to the fact that the lizard protein is about 50 percent identical to glucagon-like peptide-1 analog (GLP-1), a hormone released from the human digestive tract يساعد على تنظيم الإنسولين والگلوكاگون. The lizard protein remains effective much longer than the human hormone, helping diabetics keep their blood sugar levels under control. Exenatide slows the emptying of the stomach and causes a decrease in appetite, contributing to weight loss. The saliva of the Gila monster contains many chemicals which can be deadly. One of these has been shown to affect memory. Several companies have been researching the abilities of this chemical to help memory loss due to various diseases such as Alzheimer’s, schizophrenia, and ADHD. Gilatide, derived from exendin-4, has been shown to dramatically heighten memory in a study with mice. Gilatide is likely to be researched further to provide help to Alzheimer’s patients.

تاريخ الحياة

The Gila monster emerges from hibernation in the months of January or February and mates in May and June. The male initiates courtship by flicking his tongue to search for the female's scent. If the female rejects his advances, she will bite him and crawl away. When successful, copulation has been observed to last from 15 minutes to as long as 2.5 hours. The female will lay eggs in July or August, burying them in sand 12.7 centiمترs (5.0 بوصة) below the surface. The clutch consists of two to twelve eggs, with five being the average clutch. The process of incubation lasts nine months, as the hatchlings emerge during the months of April through June the following year. The hatchlings are about 16 centiمترs (6.3 بوصة) long and are able to bite and inject venom upon hatching. The juveniles typically have larger bands of pink scales than adults, although the banded Gila monster (H. s. cinctum) has a tendency to retain the band pattern. H. suspectum sexually matures at 3–5 years. After egg-laying, adult Gila monsters gradually spend less time on the surface to avoid the hottest part of the summer (although they may be active in the evening), eventually starting their hibernation around November.

Little is known about the social behavior of H. suspectum, but they have been observed engaging in male-male combat, in which the dominant male lies on top of the subordinate one and pins it with its front and hind limbs. Both lizards arch their bodies, pushing against each other and twisting around in an effort to gain the dominant position. A wrestling match ends when the pressure exerted forces them to separate, although bouts may be repeated over a continuous amount of time. These bouts are typically observed just before the mating season. It is thought that those with greater strength and endurance win more often and enjoy greater reproductive success. Although the Gila monster has a low metabolism and one of the lowest lizard sprint speeds, it has one of the highest aerobic scope values (زيادة استهلاك الأكسجين وقت الراحة للحصول على أقصى قدر من التمثيل الغذائي) في السحالي، allowing them to engage in intense aerobic activity for a sustained period of time. It has been observed that males have a higher aerobic scope than females, presumably because of sexual selection for a trait advantageous in prolonged combat. The Gila monster may live up to 20 years in the wild, or 30 in captivity.

حالة الحفاظ

Urban sprawl and habitat destruction has adversely affected Gila monster numbers. As a result, Gila monsters are protected by أريزونا ونـِڤادا state law; it is illegal to "harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect the Gila Monster." In 1952, they became the first venomous animal to be given legal protection. Gila monsters are listed as Near Threatened by the الاتحاد العالمي للحفاظ على الطبيعة. In 1963, the San Diego Zoo became the first zoo to successfully breed Gila monsters in captivity.

العلاقة مع البشر

Though the Gila monster is venomous, its laggard movement means that it poses little threat to humans. However, it has earned a fearsome reputation and is often killed by humans because of fear. Among Native American tribes, the Gila monster had a mixed standing. The Apache believed that its breath could kill a man, and the Tohono O'Odham and the Pima believed that it possessed a spiritual power that could cause sickness. In contrast, the Seri and the Yaqui believed that the Gila monster's hide had healing properties. The Gila monster has even starred as a monster in a B movie, The Giant Gila Monster. Myths that the animal's breath is toxic enough to kill humans or that it can spit venom or leap several feet in the air to attack are all false. Another myth held that the Gila monster did not have an anus and therefore expelled waste from its mouth, the source of its venom and "fetid breath". The official mascot of Eastern Arizona College located in Thatcher, Arizona is Gila Hank, a gun-toting, cowboy hat-wearing Gila Monster.

معرض الصور

المصادر

قراءات إضافية

مشاع الفهم فيه ميديا متعلقة بموضوع Heloderma suspectum.

• Beck, Daniel D. (2005). Biology of Gila Monsters and Beaded Lizards. Berkeley: University of California Press. ISBN .
• Bogert, Charles M. (1956). The Gila Monster and its allies: the relationships, habits, and behavior of the lizards of the Family Helodermatidae. New York: Bull. Amer. Mus. Natur. Hist. 109:1–238. p. 238. Unknown parameter |coauthors= ignored (|author= suggested) (help) Online .pdf
• Capula, Massimo (1989). Simon & Schuster's Guide to Reptiles and Amphibians of the World. نيويورك: Simon & Schuster. ISBN . Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Carmony, Neil B.; Brown, David (1991). Gila Monster: Facts and Folklore of America's Aztec Lizard. Silver City, NM: High-Lonesome Books. ISBN .CS1 maint: multiple names: authors list (link) Paperback (1999). ISBN . Missing or empty |title= (help)
• Cogger, Harold; Zweifel, Richard (1992). Reptiles & Amphibians. Sydney, Australia: Weldon Owen. ISBN .
• Ditmars, Raymond L (1933). Reptiles of the World: The Crocodilians, Lizards, Snakes, Turtles and Tortoises of the Eastern and Western Hemispheres. نيويورك: Macmillian. p. 321.
• Freiberg, Dr. Marcos; Walls, Jerry (1984). The World of Venomous Animals. نيوجرزي: TFH Publications. ISBN .
• Roever, J. M.; Hiser, Iona Seibert (1972). The Gila Monster. Austin, Tex: Steck-Vaughn Co. ISBN .CS1 maint: multiple names: authors list (link)