{{Short description|Species of frog}} {{For|other species of toads in the same genus|Pipa (frog)}} {{Speciesbox | image = Pipa pipa01.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name=IUCN>{{cite iucn |author=IUCN SSC Amphibian Specialist Group. |year=2023 |title=''Pipa pipa'' |volume=2023 |article-number=e.T58163A85900348 |doi=10.2305/IUCN.UK.2023-1.RLTS.T58163A85900348.en |access-date=7 August 2024}}</ref> | genus = Pipa | species = pipa | authority = (Linnaeus, 1758) | synonyms = * ''Rana pipa'' {{small|Linnaeus, 1758}} * ''Pipa americana'' {{small|Laurenti, 1768}} | range_map = Suriname Toad Pipa pipa distribution map.png | range_map_caption = Surinam toad range.<ref name=IUCN/> }}
The '''common Surinam toad''', the '''Suriname toad''', or '''star-fingered toad''' ('''''Pipa pipa'''''), is a fully-aquatic species of frog, in the family Pipidae, with a widespread range across much of tropical South America and the island of Trinidad.<ref name=iNat>{{Cite web |date=June 2023 |title=Observations • iNaturalist |url=https://www.inaturalist.org/observations?place_id=7375&subview=map&taxon_id=25462 }}</ref> The females of this species are well-known for "incubating" their eggs on their backs, in honeycomb-like depressions directly within the skin, releasing fully-formed froglets after a period of 4–5 months. ''Pipa pipa'' is an ambush predator, lying in-wait underwater for prey to inevitably wander too close, swiftly inhaling the unsuspecting creature using suction feeding. Additionally, the Surinam toad's rather flat body shape, combined with rather dark, dull coloration, serves as effective camouflage in the murky waters they inhabit, perfectly mimicking a dead leaf or piece of rotting wood as they await their next meal.
==Description== ''P. pipa'' is a strictly aquatic frog and the largest member of its genus. The species has an exceptionally depressed body, almost entirely flat and with a broad, flat, triangular head, without a tongue.<ref name="Fernandez-2017">{{Cite journal |last1=Fernandez |first1=Edward |last2=Irish |first2=Frances |last3=Cundall |first3=David |date=March 2017 |title=How a Frog, ''Pipa pipa'', Succeeds or Fails in Catching Fish |journal=Copeia |volume=105 |issue=1 |pages=108–119 |doi=10.1643/CH-16-510 |issn=0045-8511 |s2cid=90903754|doi-access=free }}</ref> The body is similar in appearance to a mottled brown leaf. The feet are broadly webbed with the front toes having small, star-like appendages. Males can grow up to {{cvt|154|mm}} long, whereas females can reach up to {{cvt|171|mm}}. Females can be distinguished not only by their length but also by their ring-shaped cloacas, visible when they are ready to breed.<ref name="Wandzel">{{Cite web|last=Wandzel|first=Kathryn|title=''Pipa pipa''|url=https://animaldiversity.org/accounts/Pipa_pipa/|url-status=live|access-date=2021-11-30|website=Animal Diversity Web|language=en|archive-url=https://web.archive.org/web/20160405143831/http://animaldiversity.org/accounts/Pipa_pipa/ |archive-date=2016-04-05 }}</ref> The skin color is mostly light brown with some darker spots on the back, providing good camouflage<ref name="Wandzel" /><ref name="National Geographic-2020">{{Cite web|date=2020-09-28|title=Surinam toads, facts and photos|url=https://www.nationalgeographic.com/animals/amphibians/facts/surinam-toad|access-date=2021-11-30|website=National Geographic|language=en|archive-url=https://web.archive.org/web/20210219100513/https://www.nationalgeographic.com/animals/amphibians/facts/surinam-toad |archive-date=2021-02-19 }}</ref> Nostrils are terminal, eyes very small, and the tympanum is missing. The limbs are in a laterally sprawled position in the plane of the body, and the fingertips are modified into four small lobes.<ref name="Trueb-2000">{{Cite journal |last=Trueb |first=Linda |author-link=Linda Trueb|date=10 January 2000 |title=Ontogeny of the Bizarre: An osteological description of ''Pipa pipa'' (Anura: Pipidae), with an account of skeletal development in the species|journal= Journal of Morphology|volume=243 |issue=1 |pages=75–104 |doi=10.1002/(SICI)1097-4687(200001)243:1<75::AID-JMOR4>3.0.CO;2-L |pmid=10629097 |s2cid=45830241 }}</ref> Absence of a tongue prevents the species from capturing prey with that organ like most other frogs, and instead suction capture is used.<ref name="Carreño-2010">{{Cite journal |last1=Carreño |first1=Carrie A. |last2=Nishikawa |first2=Kiisa C. |date=2010-06-15 |title=Aquatic feeding in pipid frogs: the use of suction for prey capture |journal=Journal of Experimental Biology |volume=213 |issue=12 |pages=2001–2008 |doi=10.1242/jeb.043380 |issn=1477-9145 |pmc=2878287 |pmid=20511513}}</ref>
The skull is hyperossified and the cranial and postcranial bones are heavily modified compared to other anurans. While the eyes are relatively small and narrow, the species has a lateral line system and neuromast organs which are assumed to help it locate prey and predators.<ref name="Fernandez-2017" />
The Surinam toad lacks dermal antimicrobial peptides that may inhibit disease agents such as chytridiomycosis and Ranavirus, which could make it slightly more susceptible to disease.<ref>{{Cite journal |last=Conlon |first=J. Michael |date=2011-01-01 |title=The contribution of skin antimicrobial peptides to the system of innate immunity in anurans |journal=Cell and Tissue Research |language=en |volume=343 |issue=1 |pages=201–212 |doi=10.1007/s00441-010-1014-4 |pmid=20640445 |s2cid=21225144 |issn=1432-0878}}</ref>
== Habitat and distribution == The Surinam toad, despite its common name, is actually native to several South American countries; as well as Suriname, it is known from Brazil (primarily the states of Acre, Amazonas, Mato Grosso, Pará and Rondônia), Bolivia, Colombia, Ecuador, French Guiana, Guyana, and Venezuela, in tropical rainforest regions to the east of the Andes.<ref>{{Cite web |date=28 December 2012 |title=Observations • iNaturalist |url=https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=25462 }}</ref> Additionally, a small population may be found in the southwestern corner of the island of Trinidad, just north of Venezuela across the Columbus Channel.<ref name=iNat/> ''Pipa pipa'' has the largest geographic distribution within its genus.<ref name="Vaz-Silva-2009" /> The Surinam toad inhabits warm, acidic, murky and slow-moving to still waterways, including streams, backwaters, ponds and seasonal pools after localized flooding; these rich waters often have a low pH due to a high concentration of organic matter and tannins.<ref name="Vaz-Silva-2009">{{Cite journal |last1=Vaz-Silva |first1=Wilian |last2=Andrade |first2=Tiago |date=2009-01-09 |title=Amphibia, Anura, Pipidae, ''Pipa pipa'': distribution extension, new state record and geographic distribution map |url=https://checklist.pensoft.net/article/17896/ |journal=Check List |language=en |volume=5 |issue=3 |pages=507–509 |doi=10.15560/5.3.507 |issn=1809-127X|doi-access=free }}</ref>
The Surinam toad is so strongly adapted for an aquatic lifestyle that on land it is helpless and scarcely able to move.<ref name="Buchacher-1993">{{Cite journal |last=Buchacher |first=Christian O. |date=1993-01-01 |title=Field studies on the small Surinam toad, ''Pipa arrabali'', near Manaus, Brazil |url=https://brill.com/view/journals/amre/14/1/article-p59_6.xml |journal=Amphibia-Reptilia |language=en |volume=14 |issue=1 |pages=59–69 |doi=10.1163/156853893X00192 |issn=1568-5381|url-access=subscription }}</ref>
== Diet == The species is an omnivorous ambush hunter. Its diet consists mostly of invertebrates, such as worms, insects, crustaceans and small fish.<ref name="Wandzel" /><ref>{{cite web |title=''Pipa Pipa'' (Suriname Toad) |url=https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/documents/ogatt/Pipa_pipa%20-%20Suriname%20Toad.pdf |access-date=9 April 2022 |website=Sta.uwi.edu}}</ref><ref>{{Cite web |title=''Pipa pipa'' |url=https://animaldiversity.org/accounts/Pipa_pipa/ |access-date=9 April 2022 |website=Animaldiversity.org}}</ref> Field caught ''Pipa pipa'' have been found with erythrinid fish species, other small ''Pipa pipa'', catfish, arthropods and amphibian skin in their stomachs.<ref name="Fernandez-2017" /> One study found that Cyclopoida made up 67%, Diptera larvae 7.3%, and Heteroptera 6.3% of prey. The skin fragments that were found in their stomach are an indication that these frogs commit cannibalism or eat their own skin which is common among amphibians. Based on these results, ''P. pipa'' is an ambush predator that will opportunistically eat anything that falls into the water or that it may encounter when occasionally foraging on land.<ref name="Alves-Pinto-2014">{{Cite journal |last=Alves-Pinto |first=Helena |date=2014 |title=Morphometric variation of ''Pipa pipa'' (Linnaeus, 1758) (Anura: Pipidae) with notes on diet and gonad development |url=https://www.researchgate.net/publication/288046861 |journal=Herpetology Notes |volume=7 |pages=347–353}}</ref>
== Feeding behavior == ''P. pipa'' employs a unique inertial suction feeding mechanism. The Surinam toad catches prey by entraining large volumes of water for ingestion and by limiting fish escape with its fingers. It uses bidirectional suction, a process the frog initiates by depressing its hyoid and retracting its clavicle.
The amount of entrained water the frog can ingest is related to its ability to actively increase its body volume. The frog's buccopharyngeal cavity (the cavity connecting the mouth and the pharynx) is very distensible and can expand substantially. It uses its entire trunk to rapidly enlarge the cavity, which expands into the lower end of the trunk. Its visceral organs{{px2}}{{mdash}}{{spcs|2|hair}}the hyoid and larynx, heart, lungs, liver, esophagus, and stomach{{px2}}{{mdash}}{{spcs|2|hair}}are arranged so as to be capable of moving rearward by up to a third of the length of the body; this gives additional space for expansion of the buccopharyngeal cavity. Laboratory observations estimate ''P. pipa'' can achieve an increase in trunk volume of 1.5 times the resting volume. The rapid (in {{circa|12}}–24 milliseconds) expansion of the buccopharyngeal cavity results in negative pressure; this creates the suction which, in turn, entrains the water containing the prey. The fish are effectively siphoned into the expanded buccopharyngeal cavity, where it remains for a time, located centrally in the trunk of the frog, not the stomach. The siphoned water is released through the frog's partially open mouth, as its internal pressure returns to normal, while its forelimbs remain raised close to the mouth, guarding against the possibility of prey escape.<ref name="Fernandez-2017" />
The species may be the only tetrapod vertebrate that can enlarge its entire trunk during suction feeding. Additionally, it has been found that ''P. pipa'' can modulate the timing of most elements of its prey capture process. For instance, it can asymmetrically or asynchronously move its jaw during the capture and manipulation of its prey.<ref name="Fernandez-2017" />
The forelimbs are used to "scoop" the prey into the mouth. Prior to capture of its prey, the forelimbs are held in a forward-flexed position so that each hand is positioned in front of the head. During prey capture, the forelimbs are extended and drawn towards the mouth. If the prey item is encountered during this movement, it is grabbed and pushed into the mouth. Otherwise it is sucked into the mouth without any use of the limbs. These frogs have a high degree of dexterity compared to other pipid species.<ref name="Fernandez-2017" />
== Reproduction == The mating period of these frogs is during the fall and winter seasons. These frogs call usually during the morning and mid-afternoon hours.<ref name="Rabb-1960" /> Males of this species do not attract females with croaks, instead producing a sharp clicking sound by snapping the hyoid bone in their throats.<ref>{{cite book|author-link=Ross Piper|author=Piper, Ross|year=2007|title=Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals|publisher=Greenwood Press}}</ref> The clicking sound resembles metallic noises. The average rate of these clicks is four clicks per second, consisting of blocks of 10 to 20 seconds per period.<ref name="Rabb-1960">{{Cite journal|last1=Rabb|first1=George B.|last2=Snedigar|first2=Robert|date=1960|title=Observations on Breeding and Development of the Surinam Toad, ''Pipa pipa''|journal=Copeia|volume=1960|issue=1|pages=40–44|doi=10.2307/1439843|jstor=1439843|issn=0045-8511}}</ref> Thereafter, the male will grab the front legs of the female in amplexus, causing the cloaca and the skin of the female to swell.<ref name="Whitefield-1984">{{Cite book|last=Whitefield|first=P.|title=Encyclopedie van het dierenrijk - Alle gewervelde dieren in woord en beeld|publisher=Uitgeverij Areopagus|year=1984|page=472|language=Dutch}}</ref> The partners rise from the floor while in amplexus and flip through the water in arcs. The couple will swim around in the water until they have to swim to the surface to breathe. Afterwards, they will swim back down to the bottom of the water. There the male will lay on his back, with the female on top of him on her stomach.<ref>{{Cite book|last=Preston-Mafham|first=Ken|title=Frogs and Toads|publisher=Apple Identifier|year=1999|page=16|language=English}}</ref> During the amplexus, the female's back is gradually swelled to a puffy condition. The male and female cloacae are brought close together, and many eggs are transferred anteriorly to the female's swollen dorsal epidermis.
The eggs, each around {{cvt|6.5|mm}} in diameter, then become implanted into the female's dorsal epidermis. During the first day the eggs on the female's back will sink into the skin and by evening will be set into the back of the female. Two days later, the yolks of most of the eggs are beneath the skin level and only parts of the jelly and outer membranes of the eggs are visible on the backs above. The coverings over the eggs will remain in the wild until the brood emerges.<ref name="Rabb-1960" /> The embryos develop through to the tadpole stage inside these pockets but do not emerge as tadpoles, instead remaining in their chambers until complete development to toadlet stage. The young toads grow a tail during their growth, but these will only be temporary because they will need the tail for inhaling oxygen. After 12 to 20 weeks, the young toads will hatch as small toads, looking identical to their parents. It takes a while for them to grow bigger since they are only 25 mm long when they are born. Once they have emerged from their mother's back, the toads begin a largely solitary life. After giving birth to the new toads, the mother slowly sheds the thin layer of skin used for birth and can begin the cycle again.<ref name="Wandzel" /><ref name="Trueb-2000" />
<gallery mode="packed"> Pipa pipa 1.jpg|The gray shape is the Surinam toad. Surinam toad (DFdB).jpg|A Surinam toad with eggs embedded in the skin Pipa pipa big.jpg|Museum specimen Pipa pipa whole body.jpg|Museum specimen: closeup </gallery>
=== Mating competition === When two males encounter each other during the mating season, there is a possibility that the two males will fight. The toads nearly press their snout to the chest or throat of the other male. During the conflict, both males make single clicks to each other, which resembles the sound that they normally use during breeding. If the toads have eye contact, they make a rapid series of these clicks. This process shows no visible movement of the vocal system. After some time, they will return to swimming, but will never lose contact with one another. One toad swims very closely above the other, touching his rival with only the front limbs. The fight between males may be long-lasting. Eventually, one of the males bites the other male and this is supposed to be the end of their encounter, although they do not always give up the fight. It may happen that the male that loses the battle does not give up and disturbs the breeding pair itself, even during reproduction.<ref name="Rabb-1960" />
== Conservation == Although the species is classified as Least Concern by the IUCN, it is subject to habitat loss and habitat fragmentation caused by agricultural expansions.<ref name="IUCN" /> Due to the deforestation and human encroachment on the Amazon rainforest, the species has been found in regions where it would not normally be encountered, such as terrestrial locations. This highlights the importance of preserving the endangered habitats that these frogs live in.<ref name="Vaz-Silva-2009" /><ref>{{Cite journal |last1=Dantas |first1=Silionamã Pereira |last2=Tavares |first2=Helane Dias |last3=Pascoal |first3=Wanieulli |last4=Saviato |first4=Mário Junior |last5=Ávila |first5=Robson Waldemar |last6=Vasconcelos |first6=Tiago Silveira |last7=Oda |first7=Fabrício Hiroiuki |date=2019-10-02 |title=New distribution records from the Brazilian Cerrado and species distribution modelling of ''Boana crepitans'', ''Lithobates palmipes'', ''Pipa pipa'', and ''Micrurus h. hemprichii'' |url=https://www.tandfonline.com/doi/full/10.1080/14888386.2019.1664931 |journal=Biodiversity |language=en |volume=20 |issue=4 |pages=149–160 |doi=10.1080/14888386.2019.1664931 |bibcode=2019Biodi..20..149D |s2cid=210782037 |issn=1488-8386|url-access=subscription |hdl=11449/228738 |hdl-access=free }}</ref>
== Captivity == thumb|''Pipa pipa'' in captivity In the aquarium, the species prefers plants and rocks to hide behind. Low light conditions are required. Because the Surinam toad excretes high amounts of ammonia, water changes have to be frequent.<ref>{{Cite web|last=Indiviglio|first=Frank|date=2009-04-03|title=Surinam Toads (''Pipa pipa'') as Pets: Acclimating New Animals and Special Considerations - Part 2 |website=That Reptile Blog |url=http://blogs.thatpetplace.com/thatreptileblog/2009/04/03/surinam-toads-pipa-pipa-as-pets-acclimating-new-animals-and-special-considerations-part-2/ |url-status=live|access-date=2021-12-30 |language=en-US |archive-date=2009-04-21 |archive-url=https://web.archive.org/web/20090421142147/http://blogs.thatpetplace.com:80/thatreptileblog/2009/04/03/surinam-toads-pipa-pipa-as-pets-acclimating-new-animals-and-special-considerations-part-2/}}</ref>
==Cultural significance== In a letter to Catherine Clarkson the poet Samuel Taylor Coleridge writes "I envy dear Southey's power of saying one thing at a time in short and close sentences, whereas my thoughts bustle along like a Surinam Toad, with little toads sprouting out of back, side, and belly, vegetating while it crawls".<ref>{{cite book|url= https://books.google.com/books?id=jNebCwAAQBAJ&q=%E2%80%9C&pg=PT99|title=Symptoms of Disorder: Reading Madness in British Literature, 1744–1845 |isbn=978-1-62196-709-5 |last1=Natali |first1=Ilaria |last2=Volpone |first2=Annalisa |date=30 March 2016|publisher=Cambria Press }}</ref>
The Surinam toad is commonly cited as an example of a trypophobia trigger.<ref name="trypophobia">{{cite web|title=Do you have trypophobia? Unofficial phobia might make your skin crawl|url=https://blog.seattlepi.com/thebigblog/2011/07/26/do-you-have-trypophobia-unofficial-phobia-might-make-your-skin-crawl/#photo-8211 |website=Blog.seattlepi.com}}</ref>
==References== {{Reflist}}
==External links== * {{Wikispecies-inline|Pipa pipa}} * {{Commons category-inline|Pipa pipa}} * [http://animaldiversity.ummz.umich.edu/site/accounts/information/Pipa_pipa.html ''Pipa pipa''], at Animal Diversity Web
{{Taxonbar|from=Q220414}} {{Authority control}}
pipa Category:Amphibians of Bolivia Category:Frogs of Brazil Category:Amphibians of Colombia Category:Amphibians of Ecuador Category:Amphibians of Guyana Category:Frogs of Peru Category:Amphibians of Suriname Category:Amphibians of Trinidad and Tobago Category:Amphibians of Venezuela Category:Amphibians described in 1758 Category:Animal taxa named by Carl Linnaeus