The Discovery and Care of the Common Surinam Toad
In 1699, 52-year-old Maria Sibylla Merian (1647-1717) travelled from her home in Amsterdam to the distant Dutch colony of Suriname. For much of her adult life the German-born entomologist and illustrator had been quietly pursuing scientific research, including the description and illustration of various plant and insect species in Europe. From a very young age Maria had been fascinated by insects and plants, and due to the tutelage of her step-father (the noted still-life painter) Jacob Marrel, she had subsequently become an incredibly talented and keen illustrator and naturalist. Indeed, by the time of her arrival in Suriname, Merian was a respected author with several publications including an illustrated book of flowers (New Book of Flowers, 1680) and an illustrated book on the lifecycle and feeding behavior of caterpillars (Caterpillars, Their Wondrous Transformation and Peculiar Nourishment from Flowers, 1683). It is of little surprise therefore that Merian was enchanted by Suriname and spent a great deal of time visiting forested sites, recording the flora and fauna that she witnessed there. In 1702, she was forced to return to Europe due to the onset of malaria, though by that time Merian had generated a remarkable collection of specimens, descriptions, and illustrations of Surinamese biodiversity that she would later publish in 1705 as The Metamorphosis of the Insects of Surinam. While the subject of the work was primarily botanical and entomological, within the volume was also illustrated a female amphibian with the somewhat surprising characteristic of carrying its’ young through the tadpole to froglet stage within a honeycomb-like structure on its dorsum. Today we know this fascinating creature to be the common surinam toad, which is the subject of this article.
There are a total of seven known species of surinam toad: Myers surinam toad (P. myersi), Carvalho’s surinam toad (P. carvalhoi), Albina surinam toad (P. aspera), Arrabal’s surinam toad (P. arrabali), Utinga surinam toad (P. snethlageae), Sabana (or dwarf) surinam toad (P. parva), and the Common surinam toad (P. pipa). Among these species only the Dwarf and Common species are routinely kept in captivity. In addition to their unique reproductive physiology, these two species of surinam toads are popular among herpetoculturists today due to their remarkable flat appearance and what naturalist Gerald Durrell once described as their looking as though they are ‘partially decomposed.’
Surinam toad are native to South America and distributed throughout, being found in the marshes, swamps, savannah, and forests of Trinidad, French Guiana, Guyana, Peru, Bolivia, Brazil, Columbia, Venezuela, Panama, and Suriname. They are frequently found in areas of relative lowland, in or quite near shaded, mildly-flowing streams or pooled water, with a sandy or muddy substrate that includes dead leaves that they use for concealment. They are also sometimes found among rocks near the edge of stream banks.
Studies suggest that Surinam toads are primarily nocturnal. During the daytime they tend to rest in the bottom of pools, rising to the surface only to breath, with feeding commencing at dusk. All known species are stable save the Myers surinam toad (P. myersi), which is endangered due to habitat loss in Panama. Carvalho’s surinam toad (P. carvalhoi) has been found to be invasive in parts of Brazil, while the Dwarf surinam toad (P. parva) has been found to be invasive in Venezuela, the latter due to anthropogenic movement caused by the international pet trade.
Surinam toads have a flat, pancake-like body with a wedge-shaped snout and small eyes. Their skin is warty and dappled, with a brown-red hue that aids them in blending in with their muddy, leaf-strewn surroundings. They are sexually dimorphic, with Common toad females being slightly larger (averaging 13.8 cm or 5.4 inches in length) than males (averaging 13 cm or 5.1 inches in length). Dwarf toads are significantly smaller than Common toads and adults are found to be under 6 cm (2.3 inches) in length. Both species have powerful, webbed hind feet and smaller, star-shaped web-less fingers that are used—coupled with tubercles running along their bodies dorsally and ventrally—to sense and acquire prey in the water column.
The recommended enclosure for a single captive Common surinam toad is the standard 150-litre (40 gallon) glass freshwater tank, though Dwarf toads could be comfortably housed within a 75-litre (20 gallon) tank. If you are interested in establishing a breeding colony, it will be important to separate males from one another, and from females after reproduction, because males are territorial and fight frequently. It is also recommended that you purchase a sliding screen tank top. Though surinam toads do not generally rest upon their hind limbs as other toads do, and prefer instead to remain in a splayed posture, when disturbed they will rush to the surface of their habitat to capture a breath. They are also extremely aggressive eaters and with a certain amount of thrust, it is possible for these toads to jettison themselves out of their tanks. Care therefore needs to be taken in maintaining an enclosure with a secure cover. Water levels in tanks can also be kept at the mid-point to assist with the minimization of escape, though keepers should take care to be certain that there is sufficient water in the tank for the toad to float, suspended in the middle of the water column, as they are sometimes want to do.
Surinam toads are highly sensitive to chemical changes within their environment because their skin absorbs both toxins and nutrients, so water quality is of utmost importance. An internal filtration system with a mild current is recommended and frequent water testing and changes of 25-50% will be necessary every few weeks.
A pH of 7.0-7.2 with moderate hardness is considered suitable, though some American breeders have remarked upon the hardy nature of the toad in relation to local water and pH adaptability.
Herpetoculturists will sometimes include leaf matter in their enclosures so as to provide a more naturalistic habitat. This should only be undertaken by experienced keepers as dead and rotting material in the water column will necessitate significant additional water quality monitoring and can impact filtration success. Water should be maintained at a consistent temperature of between 25.5-26 C (78-80 F), using a submersible heater such as those manufactured by ZooMed.
It is recommended that your tank substrate include a combination of large (>7.5 cm/3 in.) smooth river rocks and Mopani driftwood pieces. Sand, mud, and small gravel should be avoided due to the risk of gut impaction in captive toads brought about as a result of aggressive feeding. Live aquatic plants such as Indian Almond Leaf, Java Moss, and Duckweed, as well as floating artificial plants, can provide desired cover for your toad.
Most keepers believe that it is not necessary to provide a tank landing area for surinam toads. Yet, field research has shown that Albina surinam toads (P. aspera) and Carvalho’s surinam toads (P. carvalhoi) do sometimes travel outside of the pools and streams in which they dwell, and sometimes do rest on leaves and rocks above the water line. The dwarf Surinam toad (p. parva) has also been found to travel at short distances on land and to climb walls of 0.5m (approx.. 1.5 ft.) in height.
By utilizing the larger glass (150-litre) tank noted above, keepers could experiment by sectioning off a small portion above the water line so that toads can move throughout the water column and outside it, ad lib.
Surinam toads are omnivores and feed extremely aggressively. In captivity, recommended live food items for adults include feeder goldfish, guppies, platys, swordtails, mollies, minnows, krill, nightcrawlers, and crayfish. Common and dwarf toads are both toothless and tongueless, utilizing a suction/grabbing maneuver to ambush and capture prey in which the mouth is opened suddenly (causing suction) while the forelimbs pull the prey inside the mouth. As these toads are voracious and opportunistic feeders, other species should not be housed with them; they will readily consume anything living in their enclosure.
Surinam toads are known to be difficult to breed in captivity and there is no known full-proof way to encourage breeding, though one method that some breeders utilize is to lower the water temperature by approximately 5C (10F) so as to replicate the cooler, rainy season in the wild. Females will indicate their readiness with a visibly swollen ring around their cloaca and a dorsal brood patch, while males will attract females for breeding through a clicking call in the water.
Breeding is also difficult as a result of the specialized set-up required due to the behavior of paired toads. During reproduction male and female toads complete an inguinal amplexus rise, in which the male grasps the female from above and around her pelvis while she executes a series of summersaults in the water column. It is therefore recommended that a tank of at least 1.2 m (4 ft.) in depth is necessary for successful breeding.
During amplexus—which can sometimes last up to 36 hours—the female common toad can release up to 100 individual eggs, though female dwarf toads usually produce less than half that amount. The female releases individual eggs that are subsequently trapped between the male and female, where they are fertilized. As the process repeats, the fertilized eggs are compressed and eventually absorbed into the dorsum of the female, forming what ultimately appears to be a honeycomb-like cluster of dozens of eggs situated just under the surface of her skin. Once amplexus is complete, males should be removed and normal feeding should resume for both.
The eggs will remain within the female dorsum throughout the tadpole stage and will release as froglets into the water after a gestation of around 100 days. While this surprising and fascinating process may appear to be potentially life-threatening (not to mention repulsive to trypophobics), once the froglets have hatched, the female sheds the honeycomb-like dorsum patch and usually returns to normal within 10 days to two weeks.
After hatching, froglets should be removed from the tank and separated from one another. While there is some evidence in the scholarship of parental care in Common surinam toads (P. pipa), it has also been observed that froglets are cannibalistic. Froglets can be fed brine shrimp, guppy fry, and chopped blackworm and will reach full maturity in about three years. The average lifespan of the surinam toad is six years.
Surinam toads are strange yet fascinating creatures, though they are not an appropriate pet for the beginner seeking an animated, diurnal amphibian. They are, however, an excellent species for the intermediate enthusiast. With the appropriate care and feeding, owners can look forward to several years of experience with one of the oddest, yet most interesting, of toads.
John F. Taylor is the Founder and Managing Editor of ReptileApartment.com. In addition to a volume on the natural history and care of Uromastyx (Tropical Fish Hobbyist, 2008), he has published essays on the natural history and care of reptiles in Reptilia, Reptile Care, Reptiles USA, and Reptiles Magazine. He lives in Seattle, Washington, USA.
This article was originally published in Practical Reptile Keeping