Flattened Fauna Revisited

Suriname Toads and Matamata Turtles: Keeping it Weird in the Amazon

by William W. Lamar and Jay Vannini

Suriname Toad (Pipa pipa) full frontal. Note the highly sensitive, stellate tips of its front toes. Yanamono, Loreto, Peru. Image: ©Roel de Plecker 2025.

There is an excellent 40 year-old field guide to flattened fauna of the U.S. and Canada, you know, those creatures unfortunate to brave the asphalt and fail, a.k.a. road kill (Knutson, 1987). Let’s look at a couple of unique and cryptic Neotropical aquatic animals that come into this world already squashed: Suriname Toads and Matamatas.  

Young Orinoco River Matamata (Chelus orinocensis). Meta Department, Colombia. Image: ©William W. Lamar 2025.

Matamatas (Chelus fimbriata and C. orinocencis) are perhaps the world’s most bizarre turtles. They are the largest Chelid species, with shells up to 19”/half a meter or more in length between pegs. They can weigh as much as 40 lb/18 kg, with much of their “wet” weight skewed forward to the head and neck. Ridiculously rugose, with flat heads and elongate necks that resemble leafy doorstops; noses like soda straws; gigantic, toothless grinning mouths; and tiny shoe-button eyes; all encased in a rugged shell that looks like a pine-cone met a pineapple...these lowland tropical turtles look like a Pleistocene bad dream. Well, to some of us they are surpassingly beautiful. Some publications, including recent ones, refer to Matamatas as “aggressive.” Nothing could be further from the truth, and we suspect the authors’ impressions derive from photographs as opposed to actual experiences with the reptiles. To the uninitiated, admittedly, they might look a bit terrifying.

Matamatas are sluggish, often preferring to walk along the bottom as opposed to swimming. They are capable of remaining submerged for extended periods. Basking is accomplished by moving into shallow water or else swimming to the surface. When cold currents affect fish and other aquatic life in the Peruvian Amazon, we have found large Matamatas (actually sluggish and cold to the touch) treading water at the river surface. Interestingly, the tapetum lucidum of the Matamata eye will reflect light. This implies enhanced nocturnal vision. Using a flashlight, we have encountered specimens by night as they lay submerged in shallow water. Their eyes reflect red-orange.

Maria Sybilla Marian’s classic illustration of a Suriname Toad (Pipa pipa) from 1705 with fully-formed froglets emerging from its back. This is a remarkably lifelike rendition given the date it was executed, which was more than 50 years prior to its description by Linnaeus as Rana pipa. The inclusion of Mediterranean seashells and Sea Purslane (Sesuvium portulacastrum) as visual props are, however, fanciful touches. Image in the public domain, The Dwight and Helen Minnich Collection, The Minneapolis Institute of Arts.

Suriname Toads (Pipa pipa) are Matamata imitators from the world of amphibians. Although they do occur in Suriname, their range across tropical lowland South America is vast. And they are not toads, although the leathery skin, fairly bristling with keratinized pustules, makes them appear, and feel, rather toad-like. Like Matamatas, they favor lentic waters, including oxbow lakes, shallow marshes, and small creeks. They are particularly common in floating islands of Water Lettuce (Pistia stratiotes) and Water Hyacinth (Pontederia crassipes). Large specimens span about seven inches/18 cm. The flattened head, leafy appurtenances, beady eyes and huge, toothless mouth call the turtles to mind. Although the two are not remotely related, they are practically ecological equivalents. Both animals tend to be colored and patterned to either resemble the substrate or else dead leaves, and both are aquatic ambush predators that vacuum their prey whole into yawning maws. Matamatas then use their exaggerated, long necks to flush out the excess water and subdue a struggling fish before it is completely ingested. Suriname Toads, after creating bi-directional suction (accomplished by depressing the hyoid and retracting the clavicle), then usher their food (pretty much anything from insects to fishes small enough to swallow) into the buccopharyngeal cavity for some calming before sending it to the stomach for digestion. Anything not neatly vacuumed is assisted via the four long fingers adorning each forelimb. Each finger has four lobes; these may have some sort of tactile sensory function. Dexterity is more highly developed than in most anurans. The toads can open and shut the nostrils – see image below left – which are terminally situated.

Matamatas, long considered to comprise a single turtle species despite morphological and color variation noted across its range, were recently (Vargas-Ramírez et al., 2020) found to be two: one in the Orinoco Basin and elsewhere in northeastern South America (C. orinocencis is widely known as caripatúa); the other across the Amazonian lowlands to elevations of ~650’/200 masl. Suriname Toads have a similar history and recent studies indicate they also likely represent a species complex. They arose in western Amazonia and gradually dispersed across much of lowland tropical South America. An additional species (Pipa snethlagei) is somewhat similar. These animals are not, in fact, toads in the strict sense, but their leathery skin adorned with keratinized tubercles may leave one with that impression.

Now mainstays in the aquarium and live herptile trades, the ready availability of Suriname Toads makes it easy to overlook how fascinating and unusual these amphibians actually are. These extraordinary animals were first popularized by English naturalist Gerald Durrell in the 1950s, when he returned from (then) British Guiana with several live specimens destined for British zoos. Immortalized in his account of that collecting trip in a chapter titled, “The Toad with Pockets”, later editions of the “Three Singles to Adventure” (1954) travelogue included a sketch by wildlife artist Ralph Thompson of froglets emerging from the trapdoor cells on their mother’s back. In the early 1970s when this species was still a rather rare find in the European live animal trade, I (JV) kept a large tank that housed one in England. They are surprisingly active if given enough floor space and tall enough aquaria to allow them freedom of movement. Mine fed voraciously on earthworms and small fish.

Suriname Toad showing its valve-like nostrils open for breathing at the surface. Ceiba Tops, Iquitos, Loreto, Peru. Image: ©William W. Lamar 2025.

Back in 1960, herpetologists George and Mary Rabb and Robert Snedigar published astonishing studies that revealed several things about them. Unlike typical calling frogs, males use a clicking sound made by the hyoid bone in order to attract a mate. Pipa lack a tympanic membrane. Amplexus, a term referring to the classic mating embrace seen in some crabs and many amphibians, is a crucial part of external fertilization. Often the male’s grasp of the female is axial (at the armpits) but it can also be inguinal (around the waist). Suriname Toads practice the former, and after the pair flip upside down, the fertilized eggs are then pressed by the male onto the female’s back. These are immediately absorbed into cell-like openings in her epidermis. Over several months, these eggs bypass the larval stage and grow directly into tiny blackish froglets that emerge from their honeycomb nursery and swim away. Interestingly, the righting response is strongly developed in adult P. pipa, so this must be somehow suspended during mating.

The term charapa applies to the Giant River Turtle, Podocnemis expansa, in Amazonian Peru. However, in practice it is also used for other aquatic turtles. Suriname Toads (both Pipa pipa and P. snethlagei) are called charapa sapo, a reference to their turtle-like appearance. These frogs seldom emerge from the water. During our combined decades of wandering the swamps of the Neotropics only once have we found a specimen out of the water. It was concealed in a patch of Selaginella adjacent to a tiny rain pool into which it hopped upon being discovered.

A recent publication called into question the validity of Pipa snethlagei. The study was based in the Orinoco drainage of Colombia (Acosta-Galvis et al., 2016). In the Amazon of Peru, we have found P. snethlagei to be uncommon but quite distinct as compared with P. pipa, as shown in the images below. Among other things, they differ in the nature and distribution of dermal fimbriae, and the lines of epidermal sense organs, and P. snethlagei lacks the distinctive T-shaped pattern on the venter. The body is subcylindrical and rounded whereas that of P. pipa is extremely flattened dorso-ventrally. A dermal flap is usually present below the mandibular tip in P. pipa, but often lacking in P. snethlagei. The head of P. pipa is acuminate, with barbels present; the head of P. snethlagei is obtusely rounded and lacks barbels. Moreover, the arrangement of the four finger lobes differs between the two species.  Who knows? Perhaps in the study area hybridization is occurring.

Shown above, comparative images of mature examples of both Peruvian species of Pipa. Left, P. snethlagei from the Río Momoncillo, Loreto and right, P. pipa from San Pedro, Loreto. Images: ©William W. Lamar 2025.

My (WWL) mentor, Federico Medem, was the world’s leading authority on South American turtles and crocodylians. As a youth, he haunted the Frankfurt Zoo where he retrieved dead reptiles, took them to his flat and boiled them so he could study their bones. Meetings of the German Herpetological Society were intimidating owing to the presence of the great authority Robert Mertens of the Senckenberg Museum who would regularly test the attendees by producing a bone and waiting to see which of the beard-stroking professors might provide an identification. Medem sat at the rear of the room and kept to himself until one evening when Mertens held something in his open palm that none of the authorities recognized. Working his way among them, Fred reached out, turned the bone over, and pronounced it the skull of a Matamata. This correct identification launched a lifelong friendship between Medem and Mertens.

A Hiwi tribesman in Vichada, Colombia, showed me (WWL) how to find hatchling Chelus orinocencis. During the Dry Season when rivers are severely reduced in size, beaches form along the aggrading side and many of these have calm shallows behind them. Certain kinds of leaves become partially buried in the sand, leaving only their stems and bases exposed in the clear, reddish water. Buried amongst these leaves are baby Matamatas. Their exposed heads and nostrils so closely resemble the adjacent leaves that one must study each carefully in order to determine whether it be animal or vegetable.

The same Hiwi tribesman explained to me that Matamatas leave the rivers early, before they have receded too much. This, he explained, is because they find walking difficult. Indeed, the enormous head and elongate neck make the anterior portion of the turtle heavier. So, he said they negotiate the rather steep, leafy bank by crawling sideways and even backwards.  Perhaps sensing my skepticism, he proceeded to show me a nest. Sure enough, it was precisely where he indicated it would be. We then located two more, and each time he let me try my luck. 

I failed resoundingly.

Food habits the world over tend to be a mix of the prudent and imprudent. They can be locally rigid. In the Amazon of Peru, for instance, turtles with potent defensive musk are usually avoided and their vernacular names include the Quechua prefix asna, meaning stinky. Matamatas are potent stinkers, yet their defensive musk has not deterred locals from cooking and eating them. Weirdly, the Quechua prefix is not applied to them. In Colombia, however, no one will touch the turtles owing to their odor.

Shown above, an immense female Chelus cf. fimbriata weighing 31 lb/15 kg from San José de Guaviare, Guaviare Department, Colombia. This is the largest Amazon Matamata either of us has ever seen, and we both have handled more than a few sizeable examples. Images scanned from 35 mm slides: ©William W. Lamar 2025.

Both species of Matamatas are popular in the pet trade in the U.S., Europe, and eastern Asia and a well-designed Amazonian biotope aquarium or paludarium stocked with a healthy specimen and sympatric ornamental fishes are outstanding display items. While Amazon Matamatas were first bred in captivity almost 50 years ago, most of the considerable traffic in these turtles at this point appears to be from direct wild-collected or “ranched sources”. Two-inch/five cm hatchlings and other youngsters are known to have been illegally mixed with tropical fish shipments in the past, and seizures of smuggled live Matamatas occur both in their range states and in destination countries. Despite being listed mostly as being species of Least Concern by the IUCN Tortoise and Freshwater Turtle Specialist Group in a draft paper in 2023, both Matamatas are now listed on Appendix II of CITES (CITES, 2022; Wills, 2024; Lamar, pers. obs.).

The swimming ability of Matamatas apparently varies among individuals. We have observed captive animals to either be adept swimmers or to scarcely swim at all. Indeed, we are aware of some examples of these turtles drowning when kept in too-deep water, which is something herpetoculturists interested in keeping this species should bear in mind when designing enclosures for them. Captive Matamatas that spend most of their time standing in a corner of an aquarium with their hind legs and necks outstretched trying to breath are signaling their unhappiness with the setup and need a shallower environment.

One of us (WWL) found the skeleton of a large Matamata lying in Peruvian rainforest leaf-litter but far from any water source. The area, however, is subject to seasonal flooding from the Marañón River, so it seems likely this turtle perished while the forest was still inundated. Remarkably, the are images posted online of Matamatas stranded or dead on the edges of paved rural roads in Ecuador and elsewhere which, I suppose, brings us full circle to flattened critters at the beginning of this article!

Gallery

A secluded, Water Lettuce-choked pond at the Ceiba Tops ecolodge that provides refuge for both Matamatas and Suriname Toads. Vicinity of Iquitos, Loreto, Peru. Image: ©William W. Lamar

Orinoco River Matamata from Guyana. Image: ©William W. Lamar 2025.

Orinoco River Matamata (Chelus orinocencis) portrait, Meta Department, Colombia. Image: ©William W. Lamar 2025.

Amazon Matamata (Chelus fimbriata), Río Tapiche, Loreto, Peru. Image: ©William W. Lamar 2025.

Suriname Toad (Pipa pipa). San Pedro de Huashalado, Loreto, Peru. Image: ©William W. Lamar 2025.

A trio of fully formed, newly metamorphosed Suriname Toads just emerged from the cells on their mother’s back. Image: William W. Lamar 2025.

A female Suriname Toad in-situ with fully formed froglets ready to emerge from her swollen back. Caucho Caño, Río Momón, Loreto, Peru. Image: William W. Lamar 2025.

Female Suriname Toad with newly metamorphosed but free swimming young at San Pedro de Huashalado, Loreto, Peru. Image: William W. Lamar 2025.

A pair of Snethlage’s Frogs (Pipa snethlagei) in amplexus, Río Momoncillo, Loreto, Peru. Image: ©William W. Lamar 2025.

Landscape perspective of a shallow backwater of the Río Bita near Puerto Carreño in Vichada Department, Colombia. Suriname Toads, Snethlage’s Frogs, and Orinoco River Matamatas have been vouchered by zoologists on multiple occasions from this remote area (Acosta-Galvis et al., 2016; Vargas-Ramírez et al., 2020). Image: ©Jay Vannini 2025.

References

Acosta-Galvis, A. R., C. A. Lasso, and M. A. Morales-Betancourt. 2016. Ranas del género Pipa (Anura: Pipidae) de la Orinoquia colombiana: nuevos registros y comentarios sobre su taxonomía, distribución e historia natural. Biota Colombiana 17: 105–116.

Cannatella, D.C. and Trueb, L. 1988. Evolution of pipoid frogs: Intergeneric relationships of the aquatic frog family Pipidae (Anura). Zoological Journal of the Linnaean Society, 94(1): 1-38.

Convention on the International Trade in Endangered Species (CITES). 2022. Proposal to include the species Chelus fimbriata and Chelus orinocensis in Appendix II of CITES. https://cites.org/sites/default/files/documents/E-CoP19-Prop-22-R1.pdf

Dunn, E.R. 1948. American frogs of the family Pipidae. American Museum Novitates, 1384: 1-13.

Durrell, G. 1954. Three Singles to Adventure. Rupert Hart-Davis. 219 pp + map and B&W plates.

Fernandez, E., Irish, F. & Cundall, D. 2017. How a Frog, Pipa pipa, succeeds or fails in catching fish. Copeia, 105(1): 108-119.

Knutson, R. M. 1987. Flattened Fauna - A Field Guide to Common Animals of Roads, Streets, and Highways. Ten Speed Press, Berekely, CA. 88 pp.

Perez-Rojas, S. E. and Jerez, A. 2022. Comparative Integumentary Morphology in Four Species of Pipa (Anura: Pipidae) from Colombia. Papéis Avulsos De Zoologia, 62, 12 pp.

Rabb, G.B. and Rabb, M.S. 1960. On the mating and egg-laying behavior of the Surinam Toad, Pipa pipa. Copeia, 1960(4): 271.

Rabb, G.B. and Snedigar, R. 1960. Observations on breeding and development of the Surinam Toad, Pipa pipa. Copeia, 1960(1): 40.

Trueb, L. and Cannatella, D.C. 1986. Systematics, morphology, and phylogeny of genus Pipa (Anura: Pipidae). Herpetologica, 42(4): 412-449.

Trueb, L., Púgener, L.A., and Maglia, A.M. 2000. Ontogeny of the bizarre: An osteological description of Pipa pipa (Anura: Pipidae), with an account of skeletal development in the species. Journal of Morphology, 243(1): 75-104.

Vargas-Ramírez, M., S. Caballero, M. A. M.orales-Betancourt, C. A. Lasso, J. G. Martínez, M. Silva Viana, R. C. Vogt, I. P. Farias, T. Hrbek, P.D. Campbell, and U. Fritz. 2020. Genomic analyses reveal two species of matamata (Testudines: Chelidae: Chelus spp.) and clarify their phylogeography. Molecular Phylogenetics and Evolution. 148: 1-17

Wills, S. 2024. Smuggled, killed or free: three fates of the Matamata turtle. https://sumauma.com/en/raptada-morta-ou-livre-os-tres-destinos-da-tartaruga-matamata/

A very interesting look at the contemporary traffic – licit and otherwise – in live Matamatas in Colombia and Peru. A tad emotion-charged but well written and with some valuable insights into the trade routes from the wilds of Colombia’s Orinoco region to holding facilities in Iquitos, Peru. Some minor errors noted. Worth comparing with observations on trade in lives Matamatas in CITES (2022) referenced above

Zippel, K.C. 2006. Further observations of oviposition in the Surinam Toad (Pipa pipa), with comments on biology, misconceptions, and husbandry. Herpetological Review, 37(1): 60-68.

All content ©Exotica Esoterica LLC 2025®, ©William W. Lamar 2025, ©Roel de Plecker 2025, and Jay Vannini 2025.

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