ABSTRACT Clash of the titans – Chelydra serpentina versus Chelus fimbriatus Aquatic feeding in tu... more ABSTRACT Clash of the titans – Chelydra serpentina versus Chelus fimbriatus Aquatic feeding in turtles shows two possibilities of specialisations: ram feeding and suction feeding. Therefore, two exceptional representatives of each feeding lineage were studied: Chelydra serpentina and Chelus fimbriatus. The feeding kinematics of these two turtles were evaluated by analyses of high speed videos (3000fr/s), gross anatomy was elucidated by computertomographic reconstructions of the whole feeding apparatus. Chelydra serpentina of the suborder cryptodira has a massive almost rectangular skull in contrary to the arrow like cranium of Chelus fimbriatus (pleurodira). Thus, Chelydra has the disadvantage of compensating the large bow wave during the fast ram strike. In Chelus, the generated bow wave is negligible and an absolutely necessary feature for an ambush predator. The hyoid apparatus of both chelonians is large and well ossified with well developed musculature. This is required for generating highest suction forces during feeding. In Chelydra the suction is needed for compensating the repulsion of the prey, whereas Chelus uses the huge suction force mainly for complete ingestion. Both strategies – ram feeding of Chelydra serpentina and suction feeding of Chelus fimbriatus – are very successful, the only difference and maybe advantage for Chelydra lies in the possibility of modulating its feeding kinematics whereas Chelus is restricted to its stereotyped suction behaviour.
ABSTRACT This study examines the anatomy and histology of the feeding apparatus of two closely re... more ABSTRACT This study examines the anatomy and histology of the feeding apparatus of two closely related turtle species, the Malayan box turtle (Cuora amboinensis) and the yellow-margined box turtle (Cuora flavomarginata). The focus was on the kinematic patterns of terrestrial and aquatic feeding. Feeding patterns were analyzed by high-speed cinematography. Both species are able to feed on land as well as in water and are omnivorous. During terrestrial feeding (analyzed for both species), the Initial food prehension is always done by the jaws, whereas intraoral Food transport and swallowing actions are lingual-based. In aquatic feeding (analyzed for C. amboinensis only), the prey is captured by a fast Forward strike (ram feeding) of the head. Compensatory suction by hyoid depression prevents the prey from floating away during the head approach. In C. amboinensis, food transport under water involves inertial suction; additional compensatory suction movements occur. Despite the close phylogenetic relationship of the investigated species, there are differences in their head morphology—weaker jaw adductor muscles and a simplified trochlear complex in C. flavomarginata—as well as in their terrestrial feeding modes. Cuora amboinensis exhibits head and neck movements that are very similar to the inertial movements in aquatic feeding, but have no real effects on food transport on land. We hypothesize that these movements represent relicts of basic aquatic feeding patterns.
ABSTRACT We investigated the morphology of the feeding apparatus in five testudinid (tortoises) a... more ABSTRACT We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six geoemydid species using classical dissections and various histological and SEM techniques. The kinematics of the food uptake and the food transport behaviour were studied based on highspeed film recordings and high-speed cineradiography. In our experiments all geoemydids were fed on land and underwater. In both media, all types of food items (pellets, pieces of vegetables, fish and liver) were captured by the jaws. We found no differences concerning the ontogenetic status (juvenile, subadult and adult) of the specimens. The food uptake modes in geoemydids differ considerably from those described in emydids and tortoises, as the hyolingual complex remains retracted during the gape cycle. In all investigated species the food transport on land is lingual based. In some sequences, we detected a fast forward movement of the craniocervical complex upon reaching peak gape. We cannot define this kind of transport as “inertial” because there was no retraction of the head prior to neck extension and the food item stuck on the tongue surface. Our results lead to the hypothesis that the primitive mode of food uptake within the testudinoids is “jaw prehension”. In modern turtles, “lingual prehension” is an aberrant feeding modus, typical only for the highly evolved tortoises.
Feeding behavior in salamanders undergoing seasonal habitat shifts poses substantial challenges c... more Feeding behavior in salamanders undergoing seasonal habitat shifts poses substantial challenges caused by differences in the physical properties of air and water. Adapting to these specific environments, urodelans use suction feeding predominantly under water as opposed to lingual food prehension on land. This study aims to determine the functionality of aquatic and terrestrial feeding behavior in the Balkan-Anatolian crested newt (Triturus ivanbureschi) in its terrestrial stage. During the terrestrial stage, these newts feed frequently in water where they use hydrodynamic mechanisms for prey capture. On land, prey apprehension is accomplished mainly by lingual prehension, while jaw prehension seems to be the exception (16.67%) in all terrestrial prey capture events. In jaw prehension events there was no detectable depression of the hyo-lingual complex. The success of terrestrial prey capture was significantly higher when T. ivanbureschi used lingual prehension. In addition to prey capture, we studied the mechanisms involved in the subduction of prey. In both media, the newts frequently used a shaking behavior to immobilize the captured earthworms. Apparently, prey shaking constitutes a significant element in the feeding behavior of T. ivanbureschi. Prey immobilization was applied more frequently during underwater feeding, which necessitates a discussion of the influence of the feeding media on food manipulation. We also investigated the osteology of the cranio-cervical complex in T. ivanbureschi to compare it to that of the predominantly terrestrial salamandrid Salamandra salamandra.
Almost all extant testudinids are highly associated with terrestrial habitats and the few tortois... more Almost all extant testudinids are highly associated with terrestrial habitats and the few tortoises with high affinity to aquatic environments are found within the genus Manouria. Manouria belongs to a clade which forms a sister taxon to all remaining tortoises and is suitable as a model for studying evolutionary transitions within modern turtles. We analysed the feeding behaviour of Manouria emys and due to its phylogenetic position, we hypothesise that the species might have retained some ancestral features associated with an aquatic lifestyle. We tested whether M. emys is able to feed both in aquatic and terrestrial environments. In fact, M. emys repetitively tried to reach submerged food items in water, but always failed to grasp them-no suction feeding mechanism was applied. When feeding on land, M. emys showed another peculiar behaviour; it grasped food items by its jaws-a behaviour typical for aquatic or semiaquatic turtles-and not by the tongue as generally accepted as the typical feeding mode in all tortoises studied so far. In M. emys, the hyolingual complex remained retracted during all food uptake sequences, but the food transport was entirely lingual based. The kinematical profiles significantly differed from those described for other tortoises and from those proposed from the general models on the function of the feeding systems in lower tetrapods. We conclude that the feeding behaviour of M. emys might reflect a remnant of the primordial condition expected in the aquatic ancestor of the tortoises.
To date, the data published on the occurrence of the fire-bellied toad (Bombina bombina) and yell... more To date, the data published on the occurrence of the fire-bellied toad (Bombina bombina) and yellow-bellied toad (B. variegata) in the region of the Natural Park “Shumensko plato” (SE Bulgaria) are controversial. The species are included in the inventory of the protected territory, but none of them has been reported since 1934. In the range of this study we provide a field survey to investigate whether both Bombina species inhabit the park and where they can be located. We selected two study polygons where water basins are available for the toads at least in the spring. During our four year investigation we were able to detect only a single fire-bellied toad. One female specimen was captured in the spring of 2012 and recaptured in 2014. The specimen was found at an altitude of 472 m a.s.l. This is the highest habitat reported for B. bombina in Bulgaria.
This study examines the anatomy and histology of the feeding apparatus of two closely related tur... more This study examines the anatomy and histology of the feeding apparatus of two closely related turtle species, the Malayan box turtle (Cuora amboinensis) and the yellow-margined box turtle (Cuora flavomarginata). The focus was on the kinematic patterns of terrestrial and aquatic feeding. Feeding patterns were analyzed by high-speed cinematography. Both species are able to feed on land as well as in water and are omnivorous. During terrestrial feeding (analyzed for both species), the Initial food prehension is always done by the jaws, whereas intraoral Food transport and swallowing actions are lingual-based. In aquatic feeding (analyzed for C. amboinensis only), the prey is captured by a fast Forward strike (ram feeding) of the head. Compensatory suction by hyoid depression prevents the prey from floating away during the head approach. In C. amboinensis, food transport under water involves inertial suction; additional compensatory suction movements occur. Despite the close phylogeneti...
The Indochinese box turtle Cuora galbinifrons is a purely terrestrial species in its natural habi... more The Indochinese box turtle Cuora galbinifrons is a purely terrestrial species in its natural habitat; aquatic feeding has not been described for this species. The present study examines aquatic and terrestrial food uptake, intraoral transport and swallowing using high-speed films and cineradiography. These patterns differ from those in other box turtles. In both media, food uptake involves jaw prehension. Intraoral transport mechanisms under water differ depending on prey size: small items are transported by inertial suction, whereas larger items are moved by the tongue—normally a clear terrestrial strategy. Intraoral transport on land is lingual based. Pharyngeal packing phases are detectable prior to swallowing in both media. Swallowing mechanisms are similar under water and on land. Within the swallowing act, a further static phase could be detected. It is termed esophageal packing here (the bolus is retained for a certain time in the posterior third of the esophagus). The descri...
We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six ge... more We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six geoemydid species using classical dissections and various histological and SEM techniques. The kinematics of the food uptake and the food transport behaviour were studied based on highspeed film recordings and high-speed cineradiography. In our experiments all geoemydids were fed on land and underwater. In both media, all types of food items (pellets, pieces of vegetables, fish and liver) were captured by the jaws. We found no differences concerning the ontogenetic status (juvenile, subadult and adult) of the specimens. The food uptake modes in geoemydids differ considerably from those described in emydids and tortoises, as the hyolingual complex remains retracted during the gape cycle. In all investigated species the food transport on land is lingual based. In some sequences, we detected a fast forward movement of the craniocervical complex upon reaching peak gape. We cannot define this k...
ABSTRACT Clash of the titans – Chelydra serpentina versus Chelus fimbriatus Aquatic feeding in tu... more ABSTRACT Clash of the titans – Chelydra serpentina versus Chelus fimbriatus Aquatic feeding in turtles shows two possibilities of specialisations: ram feeding and suction feeding. Therefore, two exceptional representatives of each feeding lineage were studied: Chelydra serpentina and Chelus fimbriatus. The feeding kinematics of these two turtles were evaluated by analyses of high speed videos (3000fr/s), gross anatomy was elucidated by computertomographic reconstructions of the whole feeding apparatus. Chelydra serpentina of the suborder cryptodira has a massive almost rectangular skull in contrary to the arrow like cranium of Chelus fimbriatus (pleurodira). Thus, Chelydra has the disadvantage of compensating the large bow wave during the fast ram strike. In Chelus, the generated bow wave is negligible and an absolutely necessary feature for an ambush predator. The hyoid apparatus of both chelonians is large and well ossified with well developed musculature. This is required for generating highest suction forces during feeding. In Chelydra the suction is needed for compensating the repulsion of the prey, whereas Chelus uses the huge suction force mainly for complete ingestion. Both strategies – ram feeding of Chelydra serpentina and suction feeding of Chelus fimbriatus – are very successful, the only difference and maybe advantage for Chelydra lies in the possibility of modulating its feeding kinematics whereas Chelus is restricted to its stereotyped suction behaviour.
ABSTRACT This study examines the anatomy and histology of the feeding apparatus of two closely re... more ABSTRACT This study examines the anatomy and histology of the feeding apparatus of two closely related turtle species, the Malayan box turtle (Cuora amboinensis) and the yellow-margined box turtle (Cuora flavomarginata). The focus was on the kinematic patterns of terrestrial and aquatic feeding. Feeding patterns were analyzed by high-speed cinematography. Both species are able to feed on land as well as in water and are omnivorous. During terrestrial feeding (analyzed for both species), the Initial food prehension is always done by the jaws, whereas intraoral Food transport and swallowing actions are lingual-based. In aquatic feeding (analyzed for C. amboinensis only), the prey is captured by a fast Forward strike (ram feeding) of the head. Compensatory suction by hyoid depression prevents the prey from floating away during the head approach. In C. amboinensis, food transport under water involves inertial suction; additional compensatory suction movements occur. Despite the close phylogenetic relationship of the investigated species, there are differences in their head morphology—weaker jaw adductor muscles and a simplified trochlear complex in C. flavomarginata—as well as in their terrestrial feeding modes. Cuora amboinensis exhibits head and neck movements that are very similar to the inertial movements in aquatic feeding, but have no real effects on food transport on land. We hypothesize that these movements represent relicts of basic aquatic feeding patterns.
ABSTRACT We investigated the morphology of the feeding apparatus in five testudinid (tortoises) a... more ABSTRACT We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six geoemydid species using classical dissections and various histological and SEM techniques. The kinematics of the food uptake and the food transport behaviour were studied based on highspeed film recordings and high-speed cineradiography. In our experiments all geoemydids were fed on land and underwater. In both media, all types of food items (pellets, pieces of vegetables, fish and liver) were captured by the jaws. We found no differences concerning the ontogenetic status (juvenile, subadult and adult) of the specimens. The food uptake modes in geoemydids differ considerably from those described in emydids and tortoises, as the hyolingual complex remains retracted during the gape cycle. In all investigated species the food transport on land is lingual based. In some sequences, we detected a fast forward movement of the craniocervical complex upon reaching peak gape. We cannot define this kind of transport as “inertial” because there was no retraction of the head prior to neck extension and the food item stuck on the tongue surface. Our results lead to the hypothesis that the primitive mode of food uptake within the testudinoids is “jaw prehension”. In modern turtles, “lingual prehension” is an aberrant feeding modus, typical only for the highly evolved tortoises.
Feeding behavior in salamanders undergoing seasonal habitat shifts poses substantial challenges c... more Feeding behavior in salamanders undergoing seasonal habitat shifts poses substantial challenges caused by differences in the physical properties of air and water. Adapting to these specific environments, urodelans use suction feeding predominantly under water as opposed to lingual food prehension on land. This study aims to determine the functionality of aquatic and terrestrial feeding behavior in the Balkan-Anatolian crested newt (Triturus ivanbureschi) in its terrestrial stage. During the terrestrial stage, these newts feed frequently in water where they use hydrodynamic mechanisms for prey capture. On land, prey apprehension is accomplished mainly by lingual prehension, while jaw prehension seems to be the exception (16.67%) in all terrestrial prey capture events. In jaw prehension events there was no detectable depression of the hyo-lingual complex. The success of terrestrial prey capture was significantly higher when T. ivanbureschi used lingual prehension. In addition to prey capture, we studied the mechanisms involved in the subduction of prey. In both media, the newts frequently used a shaking behavior to immobilize the captured earthworms. Apparently, prey shaking constitutes a significant element in the feeding behavior of T. ivanbureschi. Prey immobilization was applied more frequently during underwater feeding, which necessitates a discussion of the influence of the feeding media on food manipulation. We also investigated the osteology of the cranio-cervical complex in T. ivanbureschi to compare it to that of the predominantly terrestrial salamandrid Salamandra salamandra.
Almost all extant testudinids are highly associated with terrestrial habitats and the few tortois... more Almost all extant testudinids are highly associated with terrestrial habitats and the few tortoises with high affinity to aquatic environments are found within the genus Manouria. Manouria belongs to a clade which forms a sister taxon to all remaining tortoises and is suitable as a model for studying evolutionary transitions within modern turtles. We analysed the feeding behaviour of Manouria emys and due to its phylogenetic position, we hypothesise that the species might have retained some ancestral features associated with an aquatic lifestyle. We tested whether M. emys is able to feed both in aquatic and terrestrial environments. In fact, M. emys repetitively tried to reach submerged food items in water, but always failed to grasp them-no suction feeding mechanism was applied. When feeding on land, M. emys showed another peculiar behaviour; it grasped food items by its jaws-a behaviour typical for aquatic or semiaquatic turtles-and not by the tongue as generally accepted as the typical feeding mode in all tortoises studied so far. In M. emys, the hyolingual complex remained retracted during all food uptake sequences, but the food transport was entirely lingual based. The kinematical profiles significantly differed from those described for other tortoises and from those proposed from the general models on the function of the feeding systems in lower tetrapods. We conclude that the feeding behaviour of M. emys might reflect a remnant of the primordial condition expected in the aquatic ancestor of the tortoises.
To date, the data published on the occurrence of the fire-bellied toad (Bombina bombina) and yell... more To date, the data published on the occurrence of the fire-bellied toad (Bombina bombina) and yellow-bellied toad (B. variegata) in the region of the Natural Park “Shumensko plato” (SE Bulgaria) are controversial. The species are included in the inventory of the protected territory, but none of them has been reported since 1934. In the range of this study we provide a field survey to investigate whether both Bombina species inhabit the park and where they can be located. We selected two study polygons where water basins are available for the toads at least in the spring. During our four year investigation we were able to detect only a single fire-bellied toad. One female specimen was captured in the spring of 2012 and recaptured in 2014. The specimen was found at an altitude of 472 m a.s.l. This is the highest habitat reported for B. bombina in Bulgaria.
This study examines the anatomy and histology of the feeding apparatus of two closely related tur... more This study examines the anatomy and histology of the feeding apparatus of two closely related turtle species, the Malayan box turtle (Cuora amboinensis) and the yellow-margined box turtle (Cuora flavomarginata). The focus was on the kinematic patterns of terrestrial and aquatic feeding. Feeding patterns were analyzed by high-speed cinematography. Both species are able to feed on land as well as in water and are omnivorous. During terrestrial feeding (analyzed for both species), the Initial food prehension is always done by the jaws, whereas intraoral Food transport and swallowing actions are lingual-based. In aquatic feeding (analyzed for C. amboinensis only), the prey is captured by a fast Forward strike (ram feeding) of the head. Compensatory suction by hyoid depression prevents the prey from floating away during the head approach. In C. amboinensis, food transport under water involves inertial suction; additional compensatory suction movements occur. Despite the close phylogeneti...
The Indochinese box turtle Cuora galbinifrons is a purely terrestrial species in its natural habi... more The Indochinese box turtle Cuora galbinifrons is a purely terrestrial species in its natural habitat; aquatic feeding has not been described for this species. The present study examines aquatic and terrestrial food uptake, intraoral transport and swallowing using high-speed films and cineradiography. These patterns differ from those in other box turtles. In both media, food uptake involves jaw prehension. Intraoral transport mechanisms under water differ depending on prey size: small items are transported by inertial suction, whereas larger items are moved by the tongue—normally a clear terrestrial strategy. Intraoral transport on land is lingual based. Pharyngeal packing phases are detectable prior to swallowing in both media. Swallowing mechanisms are similar under water and on land. Within the swallowing act, a further static phase could be detected. It is termed esophageal packing here (the bolus is retained for a certain time in the posterior third of the esophagus). The descri...
We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six ge... more We investigated the morphology of the feeding apparatus in five testudinid (tortoises) and six geoemydid species using classical dissections and various histological and SEM techniques. The kinematics of the food uptake and the food transport behaviour were studied based on highspeed film recordings and high-speed cineradiography. In our experiments all geoemydids were fed on land and underwater. In both media, all types of food items (pellets, pieces of vegetables, fish and liver) were captured by the jaws. We found no differences concerning the ontogenetic status (juvenile, subadult and adult) of the specimens. The food uptake modes in geoemydids differ considerably from those described in emydids and tortoises, as the hyolingual complex remains retracted during the gape cycle. In all investigated species the food transport on land is lingual based. In some sequences, we detected a fast forward movement of the craniocervical complex upon reaching peak gape. We cannot define this k...
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