That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

The tadpoles of American Toads (Bufo/Anaxyrus americanus) and Fowler’s Toads (B. woodhousei fowleri), and of related US natives, are frequently collected by herpers young and old and taken home to raise.  They usually prove quite hardy, and, even on nutrient-poor diets (i.e. lettuce), transform into tiny toadlets within a few weeks.

Toad Maladies

Young toads often prove difficult to raise however, and each year I receive questions concerning the same 2 problems – bloating and paralysis (difficulty hopping, problems catching food, etc.).  I’ve run across this myself when raising American toad tadpoles for a release program in NYC, where most of the tadpoles transformed, but died soon after.

Nutritional Deficiencies

I’ve come to believe that 2 distinct problems are at work.  Difficulty in using the rear legs is probably linked to deficiency in calcium or another nutrient, but efforts to reverse it, at least in small toads, have proven unsuccessful.
Using supplements on the food given newly transformed toads helps, but we really do not know what most species, especially North American natives, actually require.
Tadpole nutrition is another area that needs investigation.  Poorly nourished tadpoles may transform, but then die several weeks later…I’ve had this happen on a number of occasions over the years, with several species, even the relatively indestructible African clawed frog (Xenopus laevis).

Bacterial Infection

Bloating is usually a byproduct of a bacterial infection, and may be connected to nutrition.  Toads already weakened by a nutritional deficiency may be more likely to become infected with bacteria that healthier clutch mates fight off – hence both symptoms in 1 toad.  This is based mainly on anecdotal evidence, but does seem to happen time and time again, and with several species.

Natural Mortality

Another point to bear in mind is that, among species that lay huge clutches, a great many tadpoles will not survive even under the best of circumstances.  Some turtles lay infertile eggs, apparently to satiate predators and take attention away from viable ones – I have no hard evidence, but I would not be surprised to learn that weaker tadpoles serve a similar function.

Feeding Tadpoles and Young Toads

Most native toad tadpoles are omnivorous.  Try to provide them with as much variety as possible, and bear in mind that, in large groups, smaller, weaker individuals are easily out-competed at feeding time.  I’ve had good luck raising tadpoles on a diet comprised of tropical fish food flakes, algae tablets and kale pre-soaked in hot water (this breaks down thick cell walls). Metamorphs (newly transformed toads) consume scores of species of leaf litter invertebrates in the wild, complicating our job in raising them.  In addition to tiny frog standards such as fruit flies, springtails and pinhead crickets, you might try collecting tiny invertebrates as toad food (please see article below).

Further Reading

Please see my article Leaf Litter Invertebrates for information on collecting live food for tiny amphibian pets.

 Haswell’s Frog tadpole image referenced from wikipedia and originally posted by LiquidGhoul

Indonesia’s Kalimantan jungle toad (aka Bornean flat-headed frog), Barboula kalimantenensis, has been declared the only frog known to lack lungs. The frog itself was not collected and described until 1978. The fact that it is lung-less was released on April 10, 2008, by Dr. David Bickford of the National University of Singapore. The picture listed here is courtesy of Dr. Bickford.

This aquatic frog, known only from the Kapaus River Basin in West Kalimantan, Borneo, relies upon its skin when breathing in its habitat’s cold, highly-oxygenated waters. Its flat shape may increase the surface available for oxygen absorption, but little else is known about its natural history. Since lungs increase buoyancy, their loss may be an adaptation to life in fast-moving waters (the frog might more easily remain stable at the stream’s bottom).

Many salamanders (i.e. North America’s red-backed salamander, Plethodon cinereus) and I species of caecilian (legless amphibians) are lung-less. Most frogs, especially aquatic species such as the African clawed frog, Xenopus laevis, a popular pet, use cutaneous respiration on occasion. Others have unusual means of assisting their lungs – the Lake Titicaca frog, Telmatobius culeus, does “push-ups” to increase water flow to its oxygen-absorbing skin folds, and male West African hairy frogs, Trichobatrachus robustus, obtain oxygen via hair-like skin projections.

Logging and mining are degrading water quality in the Kalimantan jungle toad’s streams, and threaten its continued existence.

You can read more about the frogs mentioned here at:
www.globalamphibians.org