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Research News: How Snakes Survive and Continue to Grow Despite Food Deprivation

Snakes are well known for their abilities to survive long fasts – up to 2 years in some cases – without ill effect.  Working with ball pythons, diamondback rattlesnakes and various rat snakes, researchers at the University of Arkansas have recently shown that fasting snakes slow their metabolisms by up to 80%, and yet continue to grow even when food is withheld for 6 months.

Ball Pythons, the Champion Fasters

The reduced rate of metabolism may explain why many snakes lose little weight when fasting.  Keyed by circadian rhythms (“internal clocks”), ball pythons are notoriously worrisome to pet keepers in this regard.  Most refuse food for long periods of time each year, yet remain in good condition…in fact, the longest-lived captive snake is believed to be a ball python that attained approximately 51 years of age at the Philadelphia Zoo.

Growing Without Eating

The fact that fasting snakes continue to grow suggests that large size confers important survival advantages.  If it did not, precious fat reserves would not be allocated to growth during food emergencies.

Evidence from Zoo Animals – the Gharial

Other reptiles and amphibians seem possessed of similar abilities, although confirmation is lacking.  Fish-eating crocodilians known as Indian gharials (Gavialis gangeticus) are one example.  A group of 8 at the Bronx Zoo ceased feeding in tune with the cool season in their native Pakistan each year for the nearly 20 years that they were under my care.  They fasted for 3 months, but continued to move about and bask, and lost little of their 400-600 pound bulk during that time.

Other Reptile Pets

Bearded dragons and temperate zone reptiles, such as box and Eastern painted turtles, often stop feeding during the winter, even if kept warm.  Bearded dragons usually become largely inactive, but turtles often move about normally.  Despite this apparent use of energy, they lose little if any weight.

Interestingly, at least for turtles, individuals born in captivity usually remain active during the winter if kept warm, while wild-caught specimens typically go off feed for 2-6 months.

Know Your Pets’ Needs

Providing your pet with proper care and a healthful diet is vital if it is to survive seasonal fasts.  Be sure to research the species that you keep carefully.  Please consult our reptile and amphibian care books, and don’t hesitate to write in with any questions you may have.

Further Reading

To learn more about hibernation and fasting periods, please see my article Hibernation in Bearded Dragons and other Reptiles and Amphibians.



Interesting Facts about the Anatomy and Natural History of the Chameleons


In both captivity and nature, chameleons (Family Chamaeleonidae) stand alone – unique in so many ways, they are truly marvelous creatures to know and care for.  Today I would like to highlight a few unusual facts about these favored reptile pets.

Cultural Significance

Chameleons have long drawn our attention…in fact, their fossilized remains have been found alongside proto-human skeletons in Tanzania’s Olduvai Gorge.  Throughout Africa and Madagascar, they were regarded as somewhat mystical creatures, spying on people with their oddly-shaped eyes and reporting back to the deities about our (many!) shortcomings.

Fortunately, most of these beliefs also prohibited people from harming chameleons, and even today there are those who will risk a car accident rather than run one over.


To date, 178 chameleon species have been described.  The smallest (pygmy leaf chameleons, Genus Brookesia), barely reach 1.5 inches in length while the family’s giant, Oustalet’s chameleon (Furcifer oustaleti) may be 30 inches or more from nose to tail tip.

Range and Habitats

Chameleons reach their greatest diversity in Madagascar.  They are also found in coastal North Africa, Africa south of the Sahara, along the western edge of the Middle East and the northern shores of the Mediterranean and in India and Sri Lanka.  Two species have been introduced to Mexico and the USA.

Often regarded as rainforest animals, chameleons have also adapted to dry forests, deserts, mountainous areas (where they endure snow) and city parks.

Moving About

Chameleons walk with a peculiar rocking motion, designed to help them blend in with swaying leaves and branches…indeed, some species are reluctant to move unless a slight breeze is blowing.

In most species, the tail may be held straight out for balance, curled around a branch as a “fifth hand” or coiled tightly during dominance displays.  Chameleons in free-fall have been observed to latch onto branches with the tail, halting their descent!

The Amazing Tongue

I could go on for a long time about chameleon tongues (fear not, I’ll contain myself!), as the surprise of first seeing one in action some 3 decades ago is still fresh in my mind.  It is certainly one of nature’s most spectacular food-gathering innovations, and completely unique to this magnificent group of lizards.

The tongue is hollow and fits over a cartilaginous (bone-like) tube known as the hyoid spike.  Depending upon the species, it may be slightly shorter than or greatly exceed the chameleon’s body in length.

The tongue is projected out towards prey by powerful accelerator muscles, and tendons attaching its base to the hyoid spike cushion the shock of impact.  Once the tongue is on its way, the chameleon can only control the length of the strike…aiming is done beforehand.

Surprisingly, the tongue’s tip is not only sticky but also very abrasive…both qualities, along with a skin flap that flips over the hapless victim, assure that few meals escape.

Retractor muscles pull the tongue back into place.  These are quite powerful, allowing the lizard to reel in prey weighing half as much as itself.  Armed in this manner, large chameleons take quite large insects, and even small birds and rodents on occasion.

Further Reading

Chameleon reproductive behavior is among the lizard-world’s most complex.  The abstract of an interesting research project is posted at http://cat.inist.fr/?aModele=afficheN&cpsidt=13694591.


Amphibian Husbandry: Tong-Feeding Canned Insects to Frogs

I frequently promote the use of canned insects as a means of providing a balanced, varied diet to amphibian and reptile pets…in my experience, very little is as important as this one factor. Free living reptiles and amphibians consume dozens, and in some cases hundreds, of prey species, and rarely fare well on a captive diet consisting of 2-3 types of insects.
Canned invertebrates are convenient…some people even rely on them in place of readily available insects such as crickets and mealworms.  However, their true value lies in providing us an opportunity to add difficult-to-obtain food animals to our pets’ diets.  Other canned species that are valuable in this regard include grasshoppers, snails and fresh water shrimp.

Insect traps, such as the Zoo Med Bug Napper will also assist you in adding a variety of species to your insectivorous pets’ diets.

Feeding Tongs – Plastic vs. Metal

When looking at the video, please note how hard the frog strikes the insect…this is common, and a very good reason to use Zoo Med Plastic Feeding Tongs with these ravenous little fellows.  Metal tongs, which can injure delicate mouth tissues, are best reserved for pets which feed gingerly or take large food items.

Green and Bronze Frogs as Pets

Green frogs are wonderful but over-looked terrarium pets.  The normal seasonal changes throughout most of the USA are sufficient to spark breeding, even among animals housed indoors, and their colors are quite attractive and variable.

Populations living south of the Carolinas have been classified as a distinct subspecies, and are popularly known as bronze frogs (Rana c. clamitans).  The individual pictured here is part of a group I established for a new amphibian exhibit at the Maritime Aquarium  in Connecticut.

Green frogs also do well in outdoor ponds (please see photo), but be sure to introduce tadpoles if your pond is unfenced – adults that are relocated often attempt to return to their home territories.

Video #2 – Small Frog vs. Large Finger

The second video shows a yearling green frog attempting to swallow my finger.  This animal was received as a tadpole (as was the adult, now 3 years old), mixed in with a shipment of feeder minnows.  Although amphibians are thought to operate largely upon instinct, learning, as you can see, plays a role as well… my hand should send this frog diving for cover.  Interestingly, those captive-raised frogs that I have placed into outdoor ponds quickly regain their “common sense” and become difficult to approach.

Further Reading

Please see my article Providing a Balanced Diet to Reptile and Amphibian Pets  for further information.


The Natural History of the Red-Tailed Ratsnake


My first contact with the strikingly marked red-tailed ratsnake came many years ago, when they were rarely seen in the pet trade.  It was a wild caught adult and showed up, unexpected, in an order sent to an animal importer for whom I worked at the time.  She would eat only birds, which, fortunately for her, were in good supply (bird imports in those years were not well managed, and shipping-related deaths were all too common).

After a few months, she was so set on an avian diet that even bird-scented rodents would not pique her interest.  Eventually, the snake was purchased by one of the few people who could supply her preferred diet – a hobbyist with access to inexpensive chicks from the chicken farm near his home on Long Island!



Red-tailed ratsnakes are placed within the family Colubridae.  They were formerly classified, along with corn, black rat and similar North American species, in the genus Elaphe.

In the pet trade, red-tailed, mandarin and bamboo rat snakes, along with Taiwan beauty snakes and similar species, are often collectively referred to as Asian or Old World ratsnakes.

Physical Description

These slenderly built snakes vary widely in color throughout their huge range, but are generally pale to emerald green, with a red or reddish tail.  A yellow band of varying width separates the green and red-colored areas.

Gray and silver individuals are common in Java, and yellow specimens are known from Thailand and the Philippines.  Orange and yellow/black speckled strains are being selectively-bred in the pet trade.

Red-tailed ratsnakes average 5 feet in length, with rare individuals reaching 7.5 feet.  Females are generally longer and stouter than males.


Red-tailed ratsnakes range widely throughout south and Southeast Asia, and occur in Myanmar, Cambodia, Indonesia, Laos, Malaysia, Thailand, Vietnam, the Philippines and on the Andaman and Nicobar Islands off India.


Mangrove swamps, primary rainforest, bamboo forests, overgrown fields, agricultural areas, brushy areas on village outskirts and large parks.

This snake is highly arboreal, often dwelling 40 feet or more above the ground, but occasionally descends to earth in search of prey.  In some areas, it is said to frequent timber and thatched-roofed dwellings.

Status in the Wild

This species’ status in the wild is largely unstudied, but they are likely threatened due to habitat loss in many areas.  However, if unmolested, red-tailed ratsnakes will take up residence on farms and near houses, where they prey upon the rodents and birds that frequent these areas.


Bats, mice, rats, squirrels and other mammals, birds and their eggs, treefrogs and lizards.

Prey is killed by constriction; the tail is highly prehensile, allowing for long strikes at fast-moving, arboreal prey.

There is some evidence that, especially in young animals, the red-tipped tail is waved as a lure to attract frogs, lizards and birds to within striking range.


Mating occurs during the rainy season, which over much of this snake’s range falls between November and March.  The eggs, 5-8 in number, are laid approximately 60 days after mating.  The clutch is deposited in a sheltered, moist location, sometimes within moss and epiphytic plants among tree branches.  The young hatch in 100-140 days, and are 12-18 inches in length.

Well-fed females can lay up to 4 clutches each year, an unusually large number for a snake.


The ratsnake’s color offers exceptionally good camouflage among vines and tree branches, and this is its first line of defense.  However, even when there is an opportunity to flee, disturbed individuals often stand their ground.

When threatened, red-tailed ratsnakes compress and inflate the first third of the body while rearing up in an “S” shaped coil.  If this display fails to intimidate the foe, they strike repeatedly.

Check back soon for an article on the captive care of the Red-tailed Ratsnake.

Image referenced from Wikipedia.

The Natural History and Captive Care of the Brazilian Rainbow Boa

Iridescent coloration is exhibited many snakes, but in none is it as spectacular as that featured by the rainbow boa (Epicrates cenchria cenchria).  The “glow”, of its brilliant coloration, caused by microscopic scale ridges that refract sunlight, have long made this species a pet trade favorite.

A rather plain colored (and less expensive!) subspecies often disappoints novices who expect it to bloom into a sparkling beauty.  This snake has now been reclassified as a distinct species, the brown or Columbian rainbow boa, Epicrates maurus.


There are 8 rainbow boa subspecies, and 11 species within the genus Epicrates.  One subspecies, E. c. barbouri, is limited in distribution to Brazil’s Marajo Island.

Interestingly, molecular research carried out in 2006 indicates that the rainbow boa is more closely related to the anaconda than to other members of its genus.


Physical Description

Rainbows average 5 feet in length, with exceptional individuals nearing 7 feet.  They vary in color from red to orange/mahogany-brown, and are patterned with dark lateral rings and spots.  In sunlight, the colors are brilliantly iridescent.


The most commonly available subspecies, E. c. cenchria, is found from southern Venezuela, Guyana and Surinam south through Brazil’s Amazon Basin.

The various subspecies occupy much of Central and South America, from Costa Rica to Argentina.


Rainbow boas may be found in wet and dry forest, scrubland, savannahs, farms and village outskirts.  They are largely nocturnal, but may be about by day during the cooler seasons.

Status in the Wild

If unmolested, rainbow boas will colonize farms and other developed areas that support large rodent populations.  In some regions, however, they are threatened by deforestation and other forms of habitat loss. Listed on CITES Appendix II.


Opossums, rats, mice, squirrels, bats, rabbits and other mammals are favored, but chickens, jacanas, iguanas, tegus and a wide variety of other animals are taken.

Like all boas, the rainbow has facial pits along the upper and lower jaws that detect heat, allowing it to locate warm-blooded prey at night.


Females give birth to live young after a gestation period of 8-12 weeks.  The number produced ranges from 2-35, and, at 15-20 inches long, they are relatively large for a snake of this size.


Light and Heat

Captive care for rainbow boas presents few difficulties, and captive longevity approaches 25 years.  Ambient temperature should be maintained at 80-85 F, with a basking site of 90 F.  Temperatures can be reduced to 75-80 F at night.

Boas do not require UVB light, but may benefit from the provision of UVA.  The Zoo Med Halogen Bulb  provides UVA and heat…a Ceramic Heat Emitter is useful for night-time heating.  A Night Viewing Bulb  will emit heat at night without disturbing your pet’s natural cycle, and will enable you to view its nocturnal activities.


Wild-caught individuals that I worked with in zoos years back were notoriously picky eaters, often holding out for chicks, spiny mice, gerbils or other such fare.  Captive bred rainbows readily take rats and mice, although they sometimes switch preferences from one to the other.

Please write in with specific husbandry questions, and see my other snake articles, such as The Captive Care of the Ball Pythonfor general care guidelines.

Further Reading

You can read about rainbow boa subspecies and related snakes such as the Cuban boa at http://www.jcvi.org/reptiles/search.php?submit=Search&genus=Epicrates.


Image referenced from Wikipedia and originally posted by KaroH.

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