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Feeding behaviour in a 'basal' tortoise provides insights on the transitional feeding mode at the dawn of modern land turtle evolution.

Natchev N, Tzankov N, Werneburg I, Heiss E - PeerJ (2015)

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Integrative Zoology, Vienna University , Vienna , Austria ; Faculty of Natural Science, Shumen University , Shumen , Bulgaria.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Selected graphics (based on a high-speed video with 500 fr/s) showing the movement patterns of jaws, hyoid, tongue and head during terrestrial food transport in M. emys; note the delay in hyoid ventral displacement relative to the start the retraction of the tongue tip, as well as the delay of both the tongue retraction and hyoid retraction relative to the start of the FO phase.Abbreviations in Appendix S1.
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fig-5: Selected graphics (based on a high-speed video with 500 fr/s) showing the movement patterns of jaws, hyoid, tongue and head during terrestrial food transport in M. emys; note the delay in hyoid ventral displacement relative to the start the retraction of the tongue tip, as well as the delay of both the tongue retraction and hyoid retraction relative to the start of the FO phase.Abbreviations in Appendix S1.

Mentions: When feeding on land, the Asian forest tortoises always grasped food by the jaws. After food uptake, one to four transport cycles followed prior to oesophageal packing (see Schwenk, 2000). The tip of the tongue was barely visible during food uptake (see Figs. 3B and 3C) indicating that the tongue was not protracted. By contrast, during transport cycles, the cyclic movements of the tongue were well visible as it was rhythmically pro- and retracted to transport the food item towards the oesophagus (Fig. 5).


Feeding behaviour in a 'basal' tortoise provides insights on the transitional feeding mode at the dawn of modern land turtle evolution.

Natchev N, Tzankov N, Werneburg I, Heiss E - PeerJ (2015)

Selected graphics (based on a high-speed video with 500 fr/s) showing the movement patterns of jaws, hyoid, tongue and head during terrestrial food transport in M. emys; note the delay in hyoid ventral displacement relative to the start the retraction of the tongue tip, as well as the delay of both the tongue retraction and hyoid retraction relative to the start of the FO phase.Abbreviations in Appendix S1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558077&req=5

fig-5: Selected graphics (based on a high-speed video with 500 fr/s) showing the movement patterns of jaws, hyoid, tongue and head during terrestrial food transport in M. emys; note the delay in hyoid ventral displacement relative to the start the retraction of the tongue tip, as well as the delay of both the tongue retraction and hyoid retraction relative to the start of the FO phase.Abbreviations in Appendix S1.
Mentions: When feeding on land, the Asian forest tortoises always grasped food by the jaws. After food uptake, one to four transport cycles followed prior to oesophageal packing (see Schwenk, 2000). The tip of the tongue was barely visible during food uptake (see Figs. 3B and 3C) indicating that the tongue was not protracted. By contrast, during transport cycles, the cyclic movements of the tongue were well visible as it was rhythmically pro- and retracted to transport the food item towards the oesophagus (Fig. 5).

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Integrative Zoology, Vienna University , Vienna , Austria ; Faculty of Natural Science, Shumen University , Shumen , Bulgaria.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus