Post by Ceratodromeus on Feb 14, 2015 3:22:03 GMT 5
Here, you can post any data regarding frogs of the genus Ceratophrys -- otherwise known as the 'Horned' or 'Pacman' frogs
I'll kick it off;
Here's an interesting paper dealing with musculature and dietary habits in C. cranwelli ( A closely related species) tadpoles.
From:Morphology and feeding in tadpoles of Ceratophrys cranwelli (Anura: Leptodactylidae) Candioti 2005
These frogs have impressive bites, even from a young age. As note above, it helps in aiding to crush small insects and crustaceans that the young take This next paper ( On the Diet of the Frogs of the Ceratophryidae: Synopsis and New Contributions; Shalk et al. 2014) Dealt not only with the dietary of adult C. ornata specifially, but the family of frogs it occupies as well. Not too suprisingly, the ietary habits of Ceratophrys frogs were not all that different.
As one would guess by looking at youtube videos of captive indiviuals, they can take mammals (mice, even small rats) but in this paper, we get a better look on their natural dietary habits.
A few relevant passages:
Quite simply put, these frogs are large enough and pack a powerful enough bite that they can pretty much take down anything they want to try to shovel into their mouths. The most interesting thing about C. ornata in particular (at least to me) is that it appears to be a specialized anuran predator.
Here, we see an example of this; predation on a spadefoot toad
However, as noted by the study above, other horned frogs are also known to take other anurans as well.
Possibly because of their fascinating dietary habits, possibly because of their neat natural coloration (See OP), these frogs have been selectively bred to show an array of color mutations. you can find a list of 'mutations' for C. ornata, and other Ceratophrys frogs Here
I'll kick it off;
Here's an interesting paper dealing with musculature and dietary habits in C. cranwelli ( A closely related species) tadpoles.
This paper provides data on the skeleton, musculature, buccal apparatus, buccopharyngeal cavity and diet of Ceratophrys cranwelli tadpoles, and attempts to contribute to the knowledge of relations between morphology and ecology in anuran larvae. Both in morphological characters and feeding habits, these tadpoles are very similar to other species within the genus.
Volumetrically, the predominant food items found in the gut are the Volvocaceae, insect remnants and crustaceans. All the other items accumulate only 2% of the total. The more represented sizes are those > 1.5 mm (29%). All the Pleurodema tadpoles offered to the starved C. cranwelli were eaten within approximately 1 h. Small prey are pursued and engulfed whole, and larger ones are grabbed at any part of the body, either tail, head or side, and swallowed piecemeal (Fig. 6).
Larson and Reilly (2003) studied the participation of several muscles in gill irrigation and feeding mechanisms. These authors argue that the m. levator mandibulae longus superf icialis is only active during feeding and hyperexpiration, and provokes a forceful closing of the mouth. In Ceratophrys cranwelli, the well-developed muscles of the levator mandibulae complex, in addition to the robust jaw sheaths, would supply the force needed to bite and tear large prey apart. The same could be inferred regarding the m. intermandibularis. This muscle is highly developed, even divided into two welldistinguishable slips, and it is supposed to cause the jaw sheaths to meet more closely during feeding (Gradwell 1972). Altig and Johnston (1989) mentioned features of the buccal apparatus which correlate with a carnivorous diet, such as terminal position of the mouth and strongly keratinized jaw sheaths and keratodonts. These authors mention two instances of the functional implications of the structure of keratodont rows: cusped, highly dense teeth (115/mm), vs. non-cusped, sparse teeth (39/mm). They predict that species belonging to the second group would be able to forage on thicker, less dense substrates and remove a larger amount per feeding stroke than the species of the first group. Ceratophrys cranwelli keratodonts are spike-like, without cusps, very numerous but spaced out (tooth density = 95/mm; intertooth distance = 5 µm), and their function possibly resembles that of the Species of the second group. Similar sharply pointed keratodonts have been described in macrophagous tadpoles of Leptobrachium (Inger 1986) and Spea bombifrons (Altig and McDiarmid 1999). With regard to prey capture, the opening of the mouth and the presence of forceful, well-keratinized sheaths limit the size of the particle to be ingested and allow it to be torn apart. This differentiates Ceratophrys from Lepidobatrachus or Hymenochirus larvae, which necessarily engulf their prey whole because of their lack of strong biting and cutting structures. This is also related to buccal cavity volume, which allows housing of large prey. The high values calculated for C. cranwelli tadpoles coincide with those recorded for other carnivores of comparable snout–vent length (C. cranwelli snout to vent length x = 18.32 mm, Wassersug and Hoff 1979).
These frogs have impressive bites, even from a young age. As note above, it helps in aiding to crush small insects and crustaceans that the young take This next paper ( On the Diet of the Frogs of the Ceratophryidae: Synopsis and New Contributions; Shalk et al. 2014) Dealt not only with the dietary of adult C. ornata specifially, but the family of frogs it occupies as well. Not too suprisingly, the ietary habits of Ceratophrys frogs were not all that different.
As one would guess by looking at youtube videos of captive indiviuals, they can take mammals (mice, even small rats) but in this paper, we get a better look on their natural dietary habits.
A few relevant passages:
We dissected 21 individuals from seven species of ceratophryids (Appendix): Ceratophrys aurita (n = 3), Ceratophrys calcarata (n = 2), Ceratophrys cranwelli (n = 2), Ceratophrys ornata (n = 2), Chacophrys pierottii (n = 9), Lepidobatrachus asper (n = 2), Lepidobatrachus laevis (n = 1). We counted and identified items in the stomach and intestine to the lowest taxonomic level possible. We grouped food items into generalized categories and calculated the percent frequency of occurrence for each species. Because most of the prey items were incomplete, and we lacked a reference collection for sizes of prey items, we did not calculate their percent volume in the gut of the specimens.
We report five new prey items for ceratophryid frogs through direct observations in the field. Three new prey items are documented for larval and post-metamorphicCeratophrys cranwelli gathered from opportunistic encounters by one of us (CMS) in the dry Chaco forest of southeast Bolivia around the community of Yapiroa, Provincia Cordillera, Departmento de Santa Cruz, Bolivia (19°36’15”S, 62°34’32”W). The dry Chaco is a xerophytic thorn forest with a distinct rainy (November–March) and dry (OctoberNovember) season, averaging 513 mm of rainfall annually in this region (Navarro and Maldonado, 2002). Another new prey item is documented from an opportunistic encounter (ERW) in the diet of adult Ceratophrys cornuta from Reserva Amazonica, Peru. Reserva Amazonica is a tourist lodge and reserve on the north bank of the Río Madre de Dios, about 15 km ENE of Puerto Maldonado, Provincia de Tambopata, Departamento de Río Madre de Dios, Peru (12°33’S, 69°03’W; 200 m) (Duellman and Koechlin, 1991). The climate is seasonally tropical with distinct rainy (October–March) and dry (May–July) seasons and an average annual rainfall of 2416 mm. The region is mapped as a humid tropical forest, but is situated near the transition between humid tropical forest and dry tropical forest (Tosi, 1960). Another new prey item is documented in the diet of Lepidobatrachus laevis from field observations at Laguna Yema Formosa, Argentina (J. Faivovich pers. comm.).
Ceratophrys ornata
Other than several references commenting on their cannibalistic tendencies (Fernández and Fernández, 1921; Noble, 1927, 1931; Cei, 1980), there is little other information on the diet of tadpoles of Ceratophrys ornata in nature (Table 1). In their laboratory study, Natale et al. (2011) offered as food tadpoles of seven different species of frogs (Table 2) known to share ponds with C. ornata in nature, all of which were consumed. These authors argued that the occurrence in nature of cannibalism by C. ornata larvae is likely rare because of low population densities of these tadpoles relative to the tadpoles of other synchronously reproducing frogs with high reproductive potential. Gallardo (1974) fed captive adult C. ornata native orthopterans, mice, and two species of frogs including C. ornata (Table 2), but also non-native gastropods and beetles. Cei (1980) commented that adult C. ornata can consume small arthropods and small vertebrates, as did Gallardo (1987a), but he did not provide any further details. In a feeding study over the course of 17 months, Braun et al. (1980) fed a single captive individual 17 species of anurans and two species of snakes (Table 1). Gallardo (1987b) and Gallardo and Varela de Olmedo (1992) report post-metamorphic individuals feeding on wide variety of vertebrates, plus arthropods and molluscs, and also reported cannibalism. The most complete examination of the natural diet of C. ornata is that of Basso (1990) who examined the contents of 34 stomachs and determined that anurans were the most important of ten different prey categories found, both volumetrically (78.50%) and numerically (45.53%). Basso (1990) concludes that C. ornata is an anuran specialist, but noted that other vertebrates (birds, rodents, and a snake) and a variety of invertebrates (mostly coleopterans, isopods, and ants) were also consumed. Dissection of two specimens revealed that, numerically, vertebrates were the most frequent food items, though we did find both gastropod and arthropod invertebrates.
Other than several references commenting on their cannibalistic tendencies (Fernández and Fernández, 1921; Noble, 1927, 1931; Cei, 1980), there is little other information on the diet of tadpoles of Ceratophrys ornata in nature (Table 1). In their laboratory study, Natale et al. (2011) offered as food tadpoles of seven different species of frogs (Table 2) known to share ponds with C. ornata in nature, all of which were consumed. These authors argued that the occurrence in nature of cannibalism by C. ornata larvae is likely rare because of low population densities of these tadpoles relative to the tadpoles of other synchronously reproducing frogs with high reproductive potential. Gallardo (1974) fed captive adult C. ornata native orthopterans, mice, and two species of frogs including C. ornata (Table 2), but also non-native gastropods and beetles. Cei (1980) commented that adult C. ornata can consume small arthropods and small vertebrates, as did Gallardo (1987a), but he did not provide any further details. In a feeding study over the course of 17 months, Braun et al. (1980) fed a single captive individual 17 species of anurans and two species of snakes (Table 1). Gallardo (1987b) and Gallardo and Varela de Olmedo (1992) report post-metamorphic individuals feeding on wide variety of vertebrates, plus arthropods and molluscs, and also reported cannibalism. The most complete examination of the natural diet of C. ornata is that of Basso (1990) who examined the contents of 34 stomachs and determined that anurans were the most important of ten different prey categories found, both volumetrically (78.50%) and numerically (45.53%). Basso (1990) concludes that C. ornata is an anuran specialist, but noted that other vertebrates (birds, rodents, and a snake) and a variety of invertebrates (mostly coleopterans, isopods, and ants) were also consumed. Dissection of two specimens revealed that, numerically, vertebrates were the most frequent food items, though we did find both gastropod and arthropod invertebrates.
Ceratophrys cornuta
Captive tadpoles of Ceratophrys cornuta were observed consuming five native species of tadpoles (Table 1; Duellman and Lizana, 1994), but nothing is known of their diet under natural conditions. The study by Duellman and Lizana (1994) of C. cornuta in the Peruvian Amazon provides the most comprehensive and detailed study of the diet of any ceratophryid. In their examination of 72 stomachs, ants, and then beetles, had the greatest proportion numerically, while vertebrates, especially anurans and mammals, contributed the most volumetrically. Duellman and Lizana (1994) also examined prey frequency across a range of size classes, finding ants were again the most frequent prey item, but particularly for juveniles and adult males. This study also documented that every age class of this species consumes anurans. A range of prey items has been documented in the diet of C. cornuta, ranging from arthropods like orthopterans and hymenopterans to vertebrates such as lizards and mammals (Table 1). It has been reported that captive individuals in the field showed a clear preference for Rhinella margartifera over other offered native frog species and non-rainforest cockroaches in the Peruvian Amazon (W.W. Lamar, pers. comm.). We add that a medium-sized (ca. 50–90 g) oryzomyine rodent (Euryoryzomys or Hylaeamys) was observed being eaten alive by an adult C. cornuta at Reserva Amazonica in the Peruvian Amazon
Captive tadpoles of Ceratophrys cornuta were observed consuming five native species of tadpoles (Table 1; Duellman and Lizana, 1994), but nothing is known of their diet under natural conditions. The study by Duellman and Lizana (1994) of C. cornuta in the Peruvian Amazon provides the most comprehensive and detailed study of the diet of any ceratophryid. In their examination of 72 stomachs, ants, and then beetles, had the greatest proportion numerically, while vertebrates, especially anurans and mammals, contributed the most volumetrically. Duellman and Lizana (1994) also examined prey frequency across a range of size classes, finding ants were again the most frequent prey item, but particularly for juveniles and adult males. This study also documented that every age class of this species consumes anurans. A range of prey items has been documented in the diet of C. cornuta, ranging from arthropods like orthopterans and hymenopterans to vertebrates such as lizards and mammals (Table 1). It has been reported that captive individuals in the field showed a clear preference for Rhinella margartifera over other offered native frog species and non-rainforest cockroaches in the Peruvian Amazon (W.W. Lamar, pers. comm.). We add that a medium-sized (ca. 50–90 g) oryzomyine rodent (Euryoryzomys or Hylaeamys) was observed being eaten alive by an adult C. cornuta at Reserva Amazonica in the Peruvian Amazon
Ceratophrys cranwelli
The tadpole diet of Ceratophrys cranwelli is the best documented for any ceratophryid species. Cannibalism by C. cranwelli tadpoles has been reported by Gallardo and Varela de Olmedo (1992). Previous studies by Vera Candioti (2005, 2007) on seven tadpole specimens documented that Volvocaceae, insects, and crustaceans comprised the largest proportion of the diet of larval C. cranwelli. The tadpoles readily consumed tadpoles of Pleurodema borelli in captivity (Vera Candioti 2005; 2007), although we add that they consume tadpoles in the wild. On 23 March 2011 at 14:15 h, one of us (CMS) observed a C. cranwelli 96 tadpole that had recently captured a fairy shrimp (Crustacea: Anostraca) in shallow water along the edge of a temporary pond. The tadpole had captured the fairy shrimp head-first and proceeded to shear off the head and consume it. The tadpole then proceeded to shear off smaller bits from the body of the fairy shrimp until it had been completely consumed. The tadpole then swam to a deeper part of the pond. The same day at 21:00 h while observing a small school of ten Phyllomedusa sauvagii (Hylidae) tadpoles slowly grazing in a temporary pond along the water’s surface, CMS observed a C. cranwelli tadpole emerge from below and grasp the venter of a P. sauvagii tadpole. The C. cranwelli tadpole shook the P. sauvagii tadpole vigorously and proceeded to disembowel it, after which the C. cranwelli tadpole swam to deeper water. The C. cranwelli tadpole did not return to consume the P. sauvagii tadpole. Both field observations and dissections have documented a wide variety of anurans and other vertebrates in the diet of post-metamorphic Ceratophrys cranwelli (Table 1; Fig. 1B). Here we add that on 23 March 2011 at 21:30 h, one of us (CMS) observed a metamorph C. cranwelli (SVL = 30 mm) consuming a recently metamorphosed P. sauvagii along the edge of a temporary pond. The Phyllomedusa sauvagii still possessed a large tail-bud and had an orange-striped color pattern on its thighs and groin (Cei, 1980), suggesting that the individual had emerged from the nearby pond (approximately 20 cm away) that night. As in other observed predation events (Schalk, 2010; Schalk and Montaña, 2011), the prey item was still alive as it was being consumed and made multiple attempts to force itself from the mouth of the C. cranwelli. During the brief periods when the P. sauvagii rested between escape attempts, the C. cranwelli used its hands and the ground to force the P. sauvagii further into its mouth. After 25 minutes, the C. cranwelli completely ingested the P. sau-vagii. This prey species has been rejected by other anu-rophagous frogs in the region (Scott and Aquino, 2005). The C. cranwelli was kept overnight to observe if there were any adverse effects of the P. sauvagii consumption on the C. cranwelli. The P. sauvagii was still retained by the C. cranwelli the following morning and the C. cranwelli was then released the following night.These observations show the additional detail that C. cranwelli is anurophagous at all age classes, including tadpoles, metamorphosed individuals (see observation above; Schalk, 2010), and adults (Schalk and Montaña, 2011). However, we cannot comment on the proportion of these prey items at various age classes, because these are based off of single observations.
The tadpole diet of Ceratophrys cranwelli is the best documented for any ceratophryid species. Cannibalism by C. cranwelli tadpoles has been reported by Gallardo and Varela de Olmedo (1992). Previous studies by Vera Candioti (2005, 2007) on seven tadpole specimens documented that Volvocaceae, insects, and crustaceans comprised the largest proportion of the diet of larval C. cranwelli. The tadpoles readily consumed tadpoles of Pleurodema borelli in captivity (Vera Candioti 2005; 2007), although we add that they consume tadpoles in the wild. On 23 March 2011 at 14:15 h, one of us (CMS) observed a C. cranwelli 96 tadpole that had recently captured a fairy shrimp (Crustacea: Anostraca) in shallow water along the edge of a temporary pond. The tadpole had captured the fairy shrimp head-first and proceeded to shear off the head and consume it. The tadpole then proceeded to shear off smaller bits from the body of the fairy shrimp until it had been completely consumed. The tadpole then swam to a deeper part of the pond. The same day at 21:00 h while observing a small school of ten Phyllomedusa sauvagii (Hylidae) tadpoles slowly grazing in a temporary pond along the water’s surface, CMS observed a C. cranwelli tadpole emerge from below and grasp the venter of a P. sauvagii tadpole. The C. cranwelli tadpole shook the P. sauvagii tadpole vigorously and proceeded to disembowel it, after which the C. cranwelli tadpole swam to deeper water. The C. cranwelli tadpole did not return to consume the P. sauvagii tadpole. Both field observations and dissections have documented a wide variety of anurans and other vertebrates in the diet of post-metamorphic Ceratophrys cranwelli (Table 1; Fig. 1B). Here we add that on 23 March 2011 at 21:30 h, one of us (CMS) observed a metamorph C. cranwelli (SVL = 30 mm) consuming a recently metamorphosed P. sauvagii along the edge of a temporary pond. The Phyllomedusa sauvagii still possessed a large tail-bud and had an orange-striped color pattern on its thighs and groin (Cei, 1980), suggesting that the individual had emerged from the nearby pond (approximately 20 cm away) that night. As in other observed predation events (Schalk, 2010; Schalk and Montaña, 2011), the prey item was still alive as it was being consumed and made multiple attempts to force itself from the mouth of the C. cranwelli. During the brief periods when the P. sauvagii rested between escape attempts, the C. cranwelli used its hands and the ground to force the P. sauvagii further into its mouth. After 25 minutes, the C. cranwelli completely ingested the P. sau-vagii. This prey species has been rejected by other anu-rophagous frogs in the region (Scott and Aquino, 2005). The C. cranwelli was kept overnight to observe if there were any adverse effects of the P. sauvagii consumption on the C. cranwelli. The P. sauvagii was still retained by the C. cranwelli the following morning and the C. cranwelli was then released the following night.These observations show the additional detail that C. cranwelli is anurophagous at all age classes, including tadpoles, metamorphosed individuals (see observation above; Schalk, 2010), and adults (Schalk and Montaña, 2011). However, we cannot comment on the proportion of these prey items at various age classes, because these are based off of single observations.
Quite simply put, these frogs are large enough and pack a powerful enough bite that they can pretty much take down anything they want to try to shovel into their mouths. The most interesting thing about C. ornata in particular (at least to me) is that it appears to be a specialized anuran predator.
Here, we see an example of this; predation on a spadefoot toad
However, as noted by the study above, other horned frogs are also known to take other anurans as well.
Possibly because of their fascinating dietary habits, possibly because of their neat natural coloration (See OP), these frogs have been selectively bred to show an array of color mutations. you can find a list of 'mutations' for C. ornata, and other Ceratophrys frogs Here
