The Surinam Toad
by Carl J. Franklin
Reprinted from Notes from Noah, the newsletter of the Northern Ohio Association of Herpetologists, Vol.29, No.11, August 2002.
Originally published in Cross Timbers Herpetologist, the Newsletter of the Dallas-Fort Worth Herpetological Society, June 2002. There's an old saying that truth is often stranger than fiction. Although that comment may be somewhat of a cliché in regards to many types of reptiles and amphibians, there are still certain species that can cause even the most seasoned herpetologist or enthusiast to take pause. With that in mind, consider long bony fingers with fleshy star shaped tips, a flat body and head with tiny beadlike black eyes, no tongue, and a means of auditory communication that consist of clicks not unlike those heard throughout the movie "The Gods Must be Crazy." Sound pretty wacky? Well it is. In fact, it is one of the first frogs that come to my mind when I think about weird frogs. Of course the creature I am referring to is the Surinam toad (Pipa pipa).
Biology and Natural History
These primitive frogs belong to the family Pipidae, which is represented by 5 genera and approximately 30 species. In fact, pipids are some of the most commonly sold frogs currently in the pet trade. This can be attested by the sheer numbers of African clawed frogs (Xenopus laevis) and "dwarf" clawed frogs (Hymenochirus sp.) that are captive bred in large numbers for scientific research and the pet trade. In fact, the African clawed frog bears the distinguished honor of facilitating research towards the production of the birth control pill, and today it remains one of the most commonly used animals in experimental and developmental biology.
The family Pipidae does have a fairly wide distribution with "new world" representatives occupying northern South America east of the Andes southward to Brazil. The "old world" representatives of the pipid frogs are distributed throughout most of sub-Saharan Africa. Members of this family share unique characteristics that distinguish them from other frogs. The absence of a tongue, inguinal amplexus (males hold onto the females by grasping their midsection), and unique skeletal features are the intrinsic qualities that make this group of frogs different from the rest.
The Surinam toad was described in 1758 by the father of modern day systematics, Carolus Linnaeus, from a specimen collected in Surinam. Males of this species attain snout vent lengths (SVL) of 106 - 154mm, while females range from 105 - 171mm in SVL. The body is depressed, the head is broad, triangular, and flat, with a pointed snout and protruding dermal flap. Dermal folds are also present at the corners of the large mouth. The skin on the dorsum is tuberculate. The toes are fully webbed, and the unwebbed fingers terminate into star-shaped (bifurcate) lobes. The base coloration of the dorsum is tan to buff gray with darker blotches of brown or black. The venter is a lighter shade than the dorsum with a dark "T" shaped marking. The transverse portion of the "T" is located on the frog's chest (Rodriguez and Duellman, 1994).
Pipa pipa, like other members of the family Pipidae, are entirely aquatic. Despite this, there have been a few sightings of this frog species out of the water and on muddy river banks at night. They are found in permanent bodies of water in forested zones which may include oxbow lakes, forest pools, lagoons, forest streams and creeks, swamps, and rivers. While visiting the Madre Selva II Biological Reserve in Loreto, Peru, young boys would frequently find these frogs entangled in their fishing nets set alongside the Rio Orosa. Given their appearance, Pipa pipa are adept at camouflage and are highly effective at blending in with dead leaves resting on the bottom of muddy waters.
Like many other species of frogs, Pipa pipa is an effective predator with a voracious appetite for a wide variety of prey items. The elongated fingers are held in front of the frog's face and are used to rapidly pull food into the mouth. The food is then passed directly to the stomach. Often these frogs remain motionless for several minutes to hours, waiting for the ideal moment to ambush their prey. Then, without warning, they lunge forward with a burst of activity that can only be described as explosive, and gulp down their meal. By observing captive specimens eat, one can also notice a small current of water being expelled from the frog's mouth after the prey is swallowed. Wild caught specimens have been known to consume a wide variety of fish, including some of considerable size in proportion to the frog's body. In 1978, Bill Duellman reported a 78mm long specimen from Santa Cedlia, Ecuador having consumed two fish -- an Erythrinus erythrinus (Erthrinidae) 30mm long and a somewhat smaller pimelodid catfish (Duellman, 1978).
Fortunately for the herpetoculturist, these frogs enjoy a "catholic" diet and will accept a wide variety of food items, including, goldfish, guppies, crayfish, earthworms, beetle grubs, drowned crickets, pieces of gizzards, slices of beef heart, and mouse entrails. Live and dead food items are accepted by this species of frog, with the latter of course being offered to them from forceps. In fact,. given the murky environs that most Pipa pipa are found in, the acceptance of dead food items may not come as much of a surprise. After all, it does stand to reason that this species possesses some sort of effective chemosensory capacity. However, more investigations are in order to fully determine the feeding dynamics and chemosensory sensitivity of this species.
Aside from looking just down-right freaky, this frog is possibly best known for its unusual mode of reproduction, as well as one of the most incredible bouts of acrobatics to ever be associated with procreation. The reproduction occurs underwater and begins with a period of courtship involving vocalizations (a series of clicks) and is followed by inguinal amplexus. Amplexus may last for several hours prior to the fertilization of eggs. Once the female is ready, the skin on her back turns reddish and swollen and she will begin surfacing for air as often as once every five minutes. A midwater turnover during their midascent is followed by a sharp upward turn. The next step involves the pair pausing while horizontal and upside down. This is concluded by the pair slowly descending while head down. During these maneuvers the female passes eggs and the male sweeps them onto her back with his feet. A new egg should be visible on the back of the female upon each completion of their descent. During reproduction a special secretion allows the eggs to remain adhered to the female's dorsum. Interestingly, this secretion will only adhere to the eggs of Pipa pipa and nothing else (Rabb and Rabb, 1961). At the end of this portion of the reproductive process, a total of up to 80 eggs, each measuring roughly 6mm in diameter, are imbedded into the female's back. Here the tadpoles complete their development and emerge as tiny replicas of their parents 100-150 days later.
Acquisition and Captive Maintenance
This species was once considered a mainstay of the tropical fish hobby. However, stringent conservation laws have prevented this species from being exported from much of its range. Fortunately for the intrepid hobbyist, wild caught specimens are occasionally made available. Currently, these specimens are arriving to the United States from Guyana. For the past two years, Guyana has exported various amphibians and reptiles up to twice a year to importers in the United States. Of course the first step in properly handling any newly acquired species of amphibian involves quarantine. However, given the aquatic nature of this species, finding a fecal sample suitable for veterinary evaluation may be difficult to procure. So, in lieu of the standard quarantine protocol, I recommend that newly acquired individuals be placed in a well filtered aquarium with at least 5-10 gallons per specimen. The new arrivals may have gone some time since their last meal and should be generously offered live fish.
In September of 2000, 1 acquired a group of three specimens. I placed all three of them in a 35 gallon aquarium with a pea gravel substrate, filtration, and various freshwater plants. I then added three dozen goldfish and watched the action. Like gladiators thrown before the lions, the unsuspecting fish never stood a chance. By the next morning every fish was gone and the frogs floated near the surface with noticeable bulges in their stomachs. The frogs seemed to be healthy and on their way towards stabilization in captivity. I had acquired a group of three specimens with the hope and intention of breeding the species in captivity. However, there are no discernable differences between males and females prior to reproduction. Did I have a pair? I began getting excited when I would near the frogs "clicking" all day and night. Obviously I at least had a male. Then I witnessed a male grab another specimen in the tank and engage in amplexus. Hot dog! I must at least have a pair! This excitement and joy was short lived as I noticed that the clicking never stopped and that every specimen would respond with clicks when they were grasped. Then I came to the realization that the clicks and amplexus were merely male testosterone-charged territorial dominance disputes. Nonetheless, it was exciting to acclimate the frogs and witness healthy behavior (albeit the artifact of captivity such as having more than one male within close proximity to another male). Due to the low volume of amphibians and reptiles that are exported from South America, I have yet to acquire a female specimen. Also, because the males have all acted so "male," I cannot wait for the next opportunity to obtain a female. This species has been bred in captivity on a number of occasions and is still quite popular among many hobbyists.
Literature Cited
Duellman, W. E. 1978. The Biology of an Equatorial Herpetofauna in Amazonian Ecuador. Misc. Publ. Mus. Nat. Hist. Univ. Kansas. 65:1-352
Rabb, G. B. and M. S. Rabb. 1961. On the mating and egg laying behavior of the Surinam toad (Pipa pipa). Copeia (1960:271-276)
Rodriguez, L. 0. and W. E. Duellman. 1994. Guide to the Frogs of the lquitos Region, Amazonian Peru. Univ. Kansas. Mus. Nat. Hist. Special Publication No. 22. 1-80
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My LFS has one in with a couple of fw eels, fw baracudas, a payara, and a few fancy plecos. It has been tempting to buy it