Overview
Every so often I like to cover a species that, while not recommended as a pet, is well worth a closer look.  One such lizard that I have had the good fortune of working with is endemic to North America, the strikingly-marked Gila Monster.

Note: Gila Monsters are bred in captivity and sometimes appear for sale in the pet trade.  Please do not let your interest in these admittedly fascinating creatures lead you to purchase one.  They are venomous, and, despite recurring rumors to the contrary, have caused human fatalities.  Gilas are considered by many to be somewhat docile and slow moving.  Having long cared for them as a zoo herpetologist, I can assure you that this is not so.  They are often inactive, but can bite with amazing speed – and, in contrast to many snakes, there is no preparatory coil or other movement to warn of their intentions. If anything, their generally calm demeanor can lull one into a sense of false security – indeed, Gila bites are among those most frequently suffered (and covered up!) by zoo keepers.  Observe them in public collections and the wild, but please leave captive care to zoos.

Physical Description
This stoutly built creature is the USA’s heaviest native lizard, outweighed only by Florida’s introduced Green Iguanas and Nile Monitors. 

The scales, underlain by boney plates known as osteoderms, are bead-like in appearance.  The body is marked in widely varying patterns of pink, black yellow and orange blotches.   The blunt tail serves as a food-storage vessel – during lean times it may lose 20% or more of its mass.  Adult size ranges from 9 to 24 inches.

Range
Two subspecies, the Reticulate Gila Monster and the Banded, are recognized.  They are found in western, central and southern Arizona and adjacent New Mexico, southwestern Utah through Nevada and from southwestern California to Sinaloa in northern Mexico.

Habitat
Although typically thought of as a desert-dwelling species, Gila Monsters do not live in overly dry, central desert areas.  Rather, they frequent arid desert fringes and habitats that are referred to as “succulent or vegetated deserts” – areas that usually support a heavy growth of succulent plants, cacti, grasses and shrubs.  They may also be found in semi-arid plains and rocky foothills, lightly wooded thickets and about farms, usually near streams, springs or other sources of moisture.  Gilas sometimes enter oak forests and in Sinaloa, Mexico, inhabit the lower slopes of mountains and nearby beaches. 

Gilas may forage above-ground but are otherwise largely fossorial.  They occupy burrows dug by gophers and other mammals or those of their own making, abandoned woodrat nests and cavities below large rocks.

Despite the arid climate prevalent in their range, Gila Monsters favor areas of high humidity and spend the vast majority of their time in fairly moist underground retreats.  When kept in dry zoo exhibits, Gilas will soak in water bowls for hours on end.

Gila Monsters are diurnal in the springtime but become largely nocturnal as summer progresses.  During the hottest parts of the year they generally appear above ground only after rains.

Status in the Wild
Gila Monster populations are declining due to habitat loss and, in some cases, collection for the pet trade.  They are protected by law in all states within their range, are listed on CITES Appendix II and classified as Near Threatened by the IUCN.

Diet
Gilas feed on slow-moving animals - most commonly young mammals still in the nest, i.e. ground squirrels, kangaroo rats, pocket gophers, rabbits and cactus mice.  They also take the eggs and chicks of doves, quail and other ground-nesting birds, lizards and their eggs, tortoise eggs, locusts and other large insects and carrion.

These lizards are well-adapted to a harsh environment in which food is often scarce.  They gorge when food is available, consuming up to 50% of their bodyweight, and in some areas eat but 3-4 large meals annually.

Reproduction
Mating occurs in April and June, with 3-12 eggs being laid from July through August.  The eggs are buried in the sand, usually in a location exposed to full sun.  The eggs do not hatch until the following May - 10 months after being laid.  This long incubation period is a function of seasonality within the Gila’s range…artificially incubated eggs have hatched in as few as 30 days.

Longevity
Captive longevity exceeds 28 years; unknown in the wild.

Lizard Venoms
The Beaded Lizard, H. horridum, 4 subspecies of which dwell in Mexico and Guatemala, is a close relative of the Gila and the only other member of the family Helodermatidae.  These 2 species were, until recently, considered to be the only venomous lizards (please see below).  In contrast to venomous snakes, the venom glands of Gila Monsters and Beaded Lizards are in the lower jaw and the teeth are grooved rather than hollow.  Venom flows into the mouth through ducts that open between the teeth and gums.  In order to insure the venom’s introduction into a prey animal or enemy, both lizards retain a firm grasp when biting. 

In 2005, researchers at Australia’s Melbourne University discovered that the Bearded Dragon, Pagona vitticeps, produces a mild venom (other Agamids are being studied).  Several monitor lizards, including the Komodo Dragon, Varanus komodoensis and the Lace Monitors V. varius, were also found to produce venoms of varying strengths.  Studies of Lace Monitor venom have revealed that it causes the lizard’s prey to rapidly loss consciousness by affecting the blood’s pressure and clotting ability.  This venom is likely the source of the strong reaction, previously attributed to oral bacteria, that is often associated with bites inflicted by monitor lizards upon people.

Miscellaneous
A synthetic version of a chemical found in the saliva of the Gila Monster is the basis of an important medication used to treat Diabetes Type II.

The species name, suspectum, was coined in 1869 by renowned herpetologist and paleontologist Edward Drinker Cope – upon noting the Gila’s grooved teeth, he “suspected” that it was venomous!  The genus name, Gila, is taken from the Gila River Basin in Arizona.
Thanks, please write in with any Gila Monster related observations or questions.  Until next time, Frank.

You can read more about the Gila Monster and the reptiles and amphibians that share its habitat at the web site of the Arizona Sonora Desert Museum:
http://www.desertmuseum.org/books/nhsd_gila.php

Image referenced from Wikipedia Commons at http://en.wikipedia.org/wiki/Image:Gila_monster2.JPG and posted by Blueag9

As summer winds down, resourceful herp keepers are presented with a unique opportunity to treat their pets to a novel food item – providing, at the same time, a source of important nutritional variety. The waning days of summer bring with them the annual die-off of untold millions of large, juicy insects – the annual and periodical cicadas.

More than 100 of the world’s 2,000+ cicada species make their home in North America, and they are widely distributed. I still hear them regularly in the heart of Manhattan, and various species are quite common in and near other large cities as well. Most have a life cycle of 2-8 years, but 7 species in the eastern USA have a 13 or 17 year cycle and a number reach adulthood in 1 year.

The entire cicada population of a given area expires within a short period, usually at the end of August or in early September in the northeastern USA. This yearly event provides a bonanza (up to 1.5 million periodical cicadas may emerge from a single acre of soil!) of nutritious food for a wide range of creatures – deer mice, wood turtles, box turtles, skunks, flying squirrels, black bears and a host of others have been observed gorging on cicadas. Even adult copperhead snakes, not normally thought of as insect eaters, partake of the feast.

If you are alert at the right time, you may find hundreds of these normally arboreal songsters, spent and about to die, on the ground. Your medium and larger sized reptile, amphibian and invertebrate pets will consume them with gusto, and you can freeze the excess for future use. Cicadas occur on every continent except Antarctica, and pets both native and exotic – American bullfrogs, African mud turtles, red-kneed tarantulas – unfailingly attack them with gusto. You can also collect the nymphs as they emerge from the ground in early summer – this usually occurs at night, and often within as short period of time as 1-7 days.

Dietary variety is an important key to keeping your pets healthy and in breeding condition. Those of us who keep insectivorous herps and invertebrates often face limited food choices. The annual cicada die-off may provide a relatively easy way for some of us to remedy that situation.

One word of caution: I have noticed that populations of annual cicadas near NYC have seemingly declined drastically in recent years. A colleague suggested that the insecticides sprayed to control mosquitoes bearing West Nile Virus may be the culprit. I tend to agree – cicadas, with their largely arboreal lifestyles, are easy targets for insecticides sprayed from airplanes (far easier targets than mosquito larvae, which seem as common as ever). I have not run into secondary poisoning problems when feeding cicadas to captive animals, but suggest that you do not collect in areas that have been commercially sprayed.

Please pass along your own ideas re alternate food sources for insectivorous pets. Thanks, until next time, Frank.

You can read more about cicadas at:
http://buzz.ifas.ufl.edu/c700home.htm

Image attributed to wikipedia: http://www.cirrusimage.com/homoptera_cicada_T_linnei.htm

Introduction
The family Scincidae, the skinks, contains over 1,200 species – more than any other family of lizards.  Skinks range throughout the Eastern and Western Hemispheres, reaching their greatest diversity in Southeast Asia, Australia and Africa.  Among its members we find some of our most common pet reptiles and least-known lizards.  The following information is meant to introduce you to their wonderful diversity of forms and lifestyles.

The Unusual Giant
The group’s largest member, the Prehensile-Tailed Skink, Corucia zebrata, reaches 28 inches in length and is unique in a number of ways – it is entirely arboreal, has a prehensile tail, is limited in range to the Solomon and surrounding islands, feeds on leaves, gives birth to 1 (rarely 2) large offspring after a gestation period of 8-9 months, and seems to have a complex social structure that includes parental care of the young.

Lifestyle and Diet
Typical skinks are elongated in form with small legs and shiny scales.  Most are secretive and, although often diurnal (active by day), spend a good deal of time below rocks, logs or leaf litter.  Legs are absent or reduced in many species, including the various African and Middle Eastern “Sandfish” (Shenops and other genera) which seem to swim as they wriggle through shifting sand dunes.  Most skinks are insectivorous, but many also take fruit, carrion and small mammals, birds, reptiles and amphibians.  Several consume vegetation exclusively.

Skink Reproduction
Almost half of the known species bear live young, and a number of these have evolved a primitive placenta.  Many oviparous (egg-laying) skinks guard their eggs, and there is evidence that females may move the egg clutch in response to disturbances. 

A Few That Break the Mold
Quite a few skink species depart from the group’s typical body plan and lifestyle.  New Guinea’s Fojia Skink, Fojia bumui, for example, has plate-like scales down the center of the back and granular scales along the sides.  It clings to vertical rock surfaces along streams, dives after small invertebrates that swim by, and climbs into bushes to sleep on large, sturdy leaves.  The genus Egernia contains at least 23 species that live in extended family groups and exhibit complex social behavior.  There are also aquatic, arboreal and fossorial skinks, some of which have scale-covered, sightless eyes.

Carl Kauffeld and New York City’s Lizards
While growing up in NYC, I was pleased to learn that New York State is home to 2 skink species – the Five-Lined Skink, Eumeces fasciatus and the Coal Skink, E. anthracinus. They are, in fact, the state’s only native lizards – Staten Island’s Eastern Fence Lizards were introduced there by none other than the Staten Island Zoo’s famed reptile man, Carl Kauffeld (to provide a source of food for lizard-eating snakes) and the Italian Wall Lizard of the Bronx, Queens and Nassau County is a pet trade escapee (I have observed free-living Wall Lizards for some time now…more on them to come).

I’ll cover specific skinks in future articles.  Until then, please write in with your comments and questions.  Thanks, Frank.

Further background information on skinks, with links to individual species, is available at:
http://www.tigr.org/reptiles/families/Scincidae.html

Frogs are full of surprises when it comes to reproduction – there are species that incubate eggs below the skin of their backs and in the vocal sacs, while others carry them wrapped about their rear legs or construct foam nests on land.  But in May of this year Boston University biologists working in Panama uncovered what may well be the oddest reproductive strategy of all – a frog that actively chooses to lay its eggs on either land or in water, depending upon the threats presented by each habitat.  To date this is the only example of an egg that can hatch in either environment, and these frogs are the only vertebrates known to show such reproductive flexibility.

When breeding near shaded ponds, hourglass frogs lay their eggs on tree leaves overhanging the water (the tadpoles drop into the water upon hatching), thus avoiding fish and other aquatic predators.  However, when utilizing ponds exposed to the sun, the majority of the frogs lay their eggs directly in the water, lest they dry out before hatching.

The “decision” is not governed genetically, because the same female frog will choose different egg laying sites when placed in a shaded or un-shaded pond.

Amphibians were the first group of vertebrates to evolve some independence from water.  Biologists are now studying the hourglass frog to determine if its unique egg-laying flexibility might shed light on the evolution of terrestrial amphibian eggs.

Keep watching and studying your animals – amazing new discoveries are a real possibility.  Please write in with your questions and observations.  Thanks, until next time, Frank.

You can read more about the hourglass treefrog and its relatives at:
http://research.amnh.org/herpetology/amphibia/references.php?id=10041

An article to be published later this month (Zootaxa; August, 2008) will announce that a newly described Thread Snake from the Caribbean island of Barbados is the smallest of the world’s 3,100+ snake species.  The Barbados Thread Snake grows to a mere 4 inches in length, is no thicker than a strand of spaghetti, and can coil comfortably atop a quarter.  It subsists largely upon ant and termite larvae, and may be threatened by habitat loss.  A relatively large hatchling – ½ of the adult size – emerges from the single egg laid by the female (perhaps there is no prey species tiny enough to support a larger brood of smaller-sized young).

A related snake, nearly as tiny, has been discovered on nearby St. Lucia.  Two snakes within the genus dwell in the southwestern USA – the other 103 species are found in Mexico, Central and South America, the Caribbean, Africa, India and Pakistan.

The Penn State biologist who discovered the snake, Blair Hedges, seems to have a quite a flair for his work – he and his colleagues have named 65 new amphibian and reptile species on Caribbean islands, including the world’s smallest lizard and smallest frog.

Islands and other isolated habitats are often home to the largest (Komodo Dragons, Aldabra and Galapagos Tortoises) and smallest animals within a group.  Islands are difficult for many animals to reach, so those that do arrive often evolve into a variety of forms (and, eventually, species) to fill the many empty niches (specialized roles within a habitat) – in fact, Darwin’s theory of evolution was sparked by his observations of this process among finches on the Galapagos Islands.  Caribbean Thread Snakes, Australia’s monitor lizards and the African Rift Lake cichlids are likely examples of this phenomenon.

Please write in with your questions and comments.  Thanks, until next time, Frank

You can read more about other species of Thread Snakes at:
http://www.tigr.org/reptiles/families/Leptotyphlopidae.html

While working with Green Anacondas in the central Venezuela llanos (please see my article Hunting Anacondas in the Venezuelan Llanos) in the late 1990’s, I was delighted to find that Black Tegus, one of my favorite lizards, were quite common in the area.  Sometimes referred to as “New World monitor lizards”, it was indeed hard not to make that comparison when watching tegus hunting.  Active and intelligent, these stout lizards ate just about everything they came across – other lizards, snakes, turtle and bird eggs, small mammals, fish, frogs, crabs, large insects and carrion - and were major predators in this flooded grassland habitat.  I managed to catch a few young tegus, but old, battle-scarred individuals were impossible to approach, fleeing with amazing speed at the slightest move in their direction.

One morning I was scanning an area where I had seen a pair of Giant Anteaters a day earlier, hoping for another look, when my binoculars picked up a co-worker doing what appeared to be an odd dance of sorts.  Upon closed inspection, I saw that he was repeatedly jumping back from a yard-long black animal that was hurling itself at his leg.

I ran over and found him in a pitched battle with a large male Black Tegu.  The animal was not cornered and had ample opportunity to turn and run, as they invariably do, but simply refused.  Nest-guarding has been reported in some populations, but among females only and there was no nest to be found here.  Upon subduing the ornery fellow I found that he was uninjured, and capable of moving normally.

The only explanation that seemed to make any sense (outside of a bad temper!) was that he had not warmed sufficiently for a fast burst of speed (it was morning, and the lizard was in grass flooded by cool water).  However, he seemed to be exerting as much energy fighting as he would have by running!  Upon being released, he continued to hold his ground until we relinquished what was obviously a prized piece of real estate.

Of course, there are general rules as to typical species’ behaviors, but reptiles and amphibians show quite a variance in “personality traits” – this may assist them in adapting to changing environmental conditions and to captivity.  Please write in with any similar observations you may have, and I’ll be sure to include them in future articles.  Thanks, until next time, Frank.

An interesting article on Black Tegus and related species is posted at:
http://www.reptilia.net/articulos_ing/027.pdf

A prolapse of the cloaca (the organ into which the digestive and excretory systems empty, and which houses the penis) is a situation that most herp keepers face at one point or another.  I have observed it most commonly in frogs, less so in salamanders and reptiles.  In a prolapse, the cloaca protrudes through the anus, and is dragged about behind the animal.  If untreated, the tissue dries out and becomes necrotic (basically, the tissue dies).  A veterinarian may be able to remove the organ, but often the animal cannot be saved at this point.

A cloacal prolapse should be treated immediately upon discovery.   A long-established and often effective measure that you can take is to place the afflicted animal in a shallow bath of sugar water.  The amount of sugar is not very important – go with 1 tablespoon per 3 ounces of water if you prefer to measure.  The sugar will draw fluids from the cloaca, allowing the animal to withdraw the organ.  You can assist with a Vaseline-coated cotton swab.

If this does not help within 20 minutes, your pet should be taken to a veterinarian (a follow-up visit is a good idea even if you are successful).  It is important that you then look at the conditions that may have led to the prolapse – dehydration, constipation, straining to expel eggs and trauma caused by scent marking (rubbing the cloaca along the substrate) – are most common.  Of course, environmental conditions must be evaluated with each species’ biology in mind – conditions that are suitable for a White’s Treefrog may cause dehydration in a Budgett’s Frog, for example.

Please write in if you have encountered this condition among your pets, and I will try to help in finding the root of the problem.  Thanks, until next time, Frank.

You can read an excellent article on other amphibian emergencies at the web site of the Arizona Exotic Animal Hospital:
http://www.azeah.com/Care-Sheets.asp?id=97

Until Next Time,

Frank

The responsive ways of North Africa’s massive Spurred Tortoise are well known to private and professional turtle keepers.  Inquisitive and alert, these arid country natives are quick to become possessive of their territories and, sometimes, owners.  They adjust rapidly to changes in their environments – two 80 pounders that I kept in a half-acre outdoor exhibit at NYC’s Prospect Park Zoo never ceased to amaze me, despite having been under my daily observation for years.

A few years ago, my mother kept an abandoned 30-pound male free-ranging in her yard until a suitable home could be found for him.  He was adopted by a friend, and in short order took over his yard – digging furiously to get at the dog next store, bullying the owner’s dog and ramming or ignoring anyone save his owner.  He never failed to appear when his owner came home, and walked over to sit near him at every opportunity.

In June of this year, a neighbor’s terrier-mix (an annoying, yappy beast, I might add!) got into the tortoise’s yard and, in true terrier fashion, made right for what looked like an easy target.  He managed to bite the tortoise’s front leg – at which point the leg was withdrawn into the shell.  As you may know, Spurred Tortoises have thickly-scaled limbs and immense strength, and use their legs as a shield against predators.  Evolving in a habitat with much larger and fiercer predators that a mere terrier, the tortoise easily pinned the animal between its massive foreleg and shell, and there it remained.

Efforts by several strong men failed to straighten the tortoise’s leg and, in fact, seemed to strengthen his resolve.  Water was poured on the animals, also to no avail.  I was unable to get to the scene, and thought an injection of a muscle-relaxer might be required.  However, I first suggested that the animals, being carefully supported, be submerged in a child’s wading pool.  Thankfully, this did the trick and the tortoise released his wrestler’s “scissor lock”.

Despite having been gnawed on for over an hour, the tortoise’s leg was unmarked.  The terrier, I must say, seemed eager to do battle once again as soon as he cleared the water from his nose – but his owner had more sense!

Any amusing herp stories to tell…please write in and I’ll do my best to share them in future articles.  Thanks, until next time, Frank.

You can read about the natural history of the African Spurred Tortoise at:

http://nlbif.eti.uva.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=374

In my own tanks and those I design for zoos and aquariums, I have long been fond of featuring exposed root systems.  I am also drawn to what used to be termed “shoreline terrariums” – exhibits highlighting shallow water fish and semi-aquatic amphibians, reptiles and invertebrates.  Zoo exhibits are often quite deep and not always equipped with lighting that meets the needs of aquatic plants, so water-tolerant land plants often fulfilled my needs.

One species I have come to depend upon is the Peace Lily, a common house plant.  Its genus contains over 40 South American and Southeast Asian species, and the leaves are fairly “generic” in appearance, and so the plant handily fits the themes of a wide range of exhibits.  I prefer the “Mauna Loa” strain, which is readily available and amazingly resilient.

Most Peace Lilies prefer slight shade, but thrive under lights and tolerate fairly dry to wet soil. In my opinion, they really come into their own, terrarium-wise, when planted or suspended in water.  They thrive for years this way, and send out truly impressive root systems in short order.  Fish, shrimp, crayfish and snails will spend hours foraging among these, and the roots also have a beneficial effect on water quality.  Their intertwined tendrils provide vital shelter to young fishes and shrimp, and lend a stunning look to planted aquariums and terrariums.

As you can see from the accompanying photo, the sturdy leaves function almost as do water lily pads, and easily support the weight of an adult Green Frog.  The other photos depict a Southern Leopard Frog resting on a leaf draped over a stump, and the extensive root system that was formed from one small plant (5 leaves).

I have even seen Peace Lilies sold for use as totally aquatic plants, but have not tried planting them in this way - please write in with your thoughts and comments.  Thanks, until next time, Frank.

Overview
Recently I wrote about those tiny jewels of the frog world, Latin America’s poison frogs (Article Part I and II).  Today I’ll introduce you to a behemoth that is largely their direct opposite, the massive Marine Toad – at once one of the world’s most interesting and troublesome of amphibians (actually, the people who have transported it around the globe are troublesome, not the toads!).

Physical Description
This largest of the world’s toads may reach 10 inches in length.  Generally brown to tan in color, some individuals show a yellow or reddish tint.  One that I received from a friend working on Guam was clad in several shades of yellow and quite beautiful. Enormous paratoid (poison) glands extend from behind the eyes to the sides of the body.  The body is squat and rounded in profile.

There seems to be a great deal of variation in size among different Marine Toad populations, with the true giants that came out of Colombia and Suriname in the 1960’s and early 70’s being rarely seen in the trade today.  I examined a great many in working in Venezuela, and most were in the 4-6 inch range (this comports with locally published accounts).  Florida’s introduced animals are relatively small in size (but large as toads go), as are those in south Texas.

The photo accompanying this article shows me holding a large female that was collected, I believe, in Colombia.  She has inflated her lungs with air to prevent my swallowing her (fat chance!) – the stick is to discourage the two 18 foot long anacondas that share her exhibit from attempting to swallow me!

Range and Habitat
People are sometimes surprised to learn that the Marine Toad is a US native, but those living in southern Texas are indeed part of a naturally occurring group.  Florida and Hawaii’s large populations are introduced.

From Texas, this toad range south from southern Sonora, Mexico through Central America to central Brazil, Amazonian Peru and Bolivia.  Marine Toads have been widely introduced and are well established in Florida, Hawaii, Taiwan, Japan, New Guinea, Australia, and throughout the islands of the Caribbean (i.e. Puerto Rico, Antilles, St. Lucia) and the South Pacific (i.e. Fiji, Guam).

Marine toads dwell in a wide variety of habitats, including open forest, overgrown scrub, grasslands, fields and marshes.  They adjust well to disturbed sites and are common in agricultural areas, suburbs and urban parks (i.e. within Miami, Fla.).  Several I observed on Tortuguero, Costa Rica, crossed a 30 foot stretch of mowed lawn each evening to feed near my bedroom’s outdoor light.

Status in the Wild
Generally common within natural range and usually very common, to the point of being a harmful invasive, where introduced.

Diet
Marine Toads consume nearly any creature that fits within their cavernous mouths - centipedes, roaches, beetles, millipedes, earthworms, land crabs, spiders and other invertebrates, frogs, lizards and snakes.  Mice, birds and similar creatures are taken when encountered, but stomach analysis of toads in the Venezuelan llanos (grasslands) showed this to be a rare occurrence in that habitat.

This is one of only a very few frog species to consume non-living food items (African Clawed Frogs, Xenopus spp. will take carrion and, amazingly, Izecksohn’s Treefrog of Brazil eats berries).  While in Costa Rica, I regularly observed a large toad eating dog food (after pushing open a screen door to get at it!), and those kept by co-workers at the Bronx Zoo ate salad set out for tortoises.  Field reports from New Guinea indicate that Marine Toads there rely upon vegetation as food during the dry season.  Stomach analysis of wild individuals indicates that they also will take carrion (chicken and fish) and the eggs of other Marine Toads. 

In addition to hunting by sight, these toads apparently utilize olfaction (rare for a terrestrial frog) as well.

Reproduction
An extremely flexible reproductive biology accounts for this animal’s success as an invasive species.  Unlike most amphibians, it can reproduce throughout the year in favorable habitats, in brackish (saline) water and in waters containing high fish populations.

Large females may lay as many as 36,000 eggs, attached in strings to aquatic vegetation.  In contrast to most frogs, both eggs and tadpoles are protected by virulent toxins.  The tadpoles take 10 days to 6 months to transform, depending upon temperature and diet, and can survive 10 hours without water.  They consume algae, dead plants, carrion and each other, and generally out-compete or eat the tadpoles of other species.  Newly transformed toads disperse widely and often establish new limits to existing ranges.

Miscellaneous
Marine toads are likely the world’s most widely introduced amphibian (American Bullfrogs and Greenhouse Frogs are close competitors for this title).  They are generally transported to agricultural areas to control insect pests, a strategy that rarely works.  In Australia, for example, the toads seldom catch cane beetles, their intended prey - the beetles dwell high above the ground and the toads do not climb.

Introduced populations expand rapidly, consume native animals and out-compete others.  On Oahu, Hawaii, 148 introduced toads multiplied to over 100,000 in a 2 year period.

The Marine Toad’s toxins are powerful and complex.  Threatened toads will lower their heads and attempt to bring the poison-containing paratoid glands in contact with the attacker.  In Australia, 3 species of quoll (a medium-sized mammal) and 8 species of monitor lizards prey upon the toads and are declining due to deaths caused by the toad’s skin toxins.  Dingoes, snakes, foxes, dogs and other animals have also expired after eating Marine Toads.

Most predators occurring within the Marine Toad’s natural range leave them strictly alone.  I have, for example, housed them with green anacondas for many years – despite that fact that the snakes will avidly consume other frog species.  However, several snake and possibly bird species have evolved toxin immunities and prey upon them.  In Australia, White-Tailed Water Rats have apparently learned to avoid the skin toxins by flipping the toads and chewing through the belly skin to reach the internal organs.

Marine toads are quite responsive to their surroundings.  Captive animals anticipate food upon seeing their keepers, and those living in developed areas learn to gather under street lights to capture insects.

Marine Toads make responsive long-lived pets - I’ll cover their care next time.   Until then, please write in with your comments and questions.  Thanks, Frank.

A field report detailing some of the unusual foods and other items found in the stomachs’ of free-living Marine Toads is posted at:
http://www.jstor.org/pss/1564710