Research topics

Our group provides insight into the variable feeding systems of all kinds of vertebrates. With the usage of high speed videography and µCT reconstruction of skull bones and musculature, we are able to describe the biomechanics during various feeding stages. Our group started around 25 years ago with turtle’s feeding modes, but proceeds now with several groups within vertebrates.

Feeding in fish

Regarding morphology and kinematics, the fish skull is very complex. Different dietary preferences and hence different trophic strategies determine the diverse and manifold skull morphology and feeding mechanisms which can be found among fishes.

Current research focuses on several species of the cyprinodontiform genus Aphanius, which are widespread across different habitats from saline via brackish to freshwater environments. Focus of current studies lies on the morphology of the feeding apparatus in Aphanius with the aim to describe the anatomy in detail and thereby prepare a foundation for further anatomical, kinematic, and evolutionary studies.

Ongoing projects:

> Feeding kinematics in Aphanius mento (Christina Kaurin)

Recently completed:

> The morphology of the feeding apparatus in Aphanius mento (Christina Kaurin)

Feeding in amphibians

Amphibians are of special interest since this vertebrate group comprises many aquatic as well as terrestrial species. Amphibians were the first tetrapod group that conquered terrestrial environment during evolution but are still closely related to water. Having a fully aquatic larval form, they metamorphose to a terrestrial form during ontogeny. Aquatic salamanders use fast mouth opening, by means of explosive oropharyngeal volume expansion to draw prey and surrounding water into the mouth. The suction feeding apparatus of aquatic salamanders was always suggested to be homologous to the mechanism used by larval salamanders which is supposed to be homologous to fishes. So the aquatic feeding mechanisms in salamanders represent a plesiomorphic condition of tetrapods and only other tetrapods use truly secondary and thus convergent suction feeding mechanisms. Frogs for example, representing the main amphibian branch with about 90% of all amphibians, are true secondary aquatic feeders. Thus, purely aquatic frogs evoked some interest in the last years as well.

We use on the one hand high-speed cinematography to describe feeding kinematics and on the other hand µCT stacks for segmentation of the necessary muscular features. 

Ongoing projects:

> Variations in feeding mechanisms in Triturus ivanbureschi (Yurii Kornilev)
> Nahrungsaufnahme-Mechanismen bei Ambystoma dumerilii (Saskia Krüger)

 Recently completed:

> Funktionsmorphologie der Nahrungsaufnahme bei Triturus dobrogicus, Kiritzescu 1903 (Urodela, Salamandridae) (Florian Kucera)
> Feeding in Ambystoma andersoni (Marlene Weberndorfer)
> Feeding mechanisms of Calyptocephalella gayi (Verena Wiesinger)
> A comparison of the feeding-apparatus of the aquatic Calyptocephallela gayi and the terrestrial Leptodactylus pentadactylus (Stephanie Kunisch)

Feeding in reptiles

Turtles comprise a very old lineage within reptiles and have an aquatic lifestyle since more than 200 million years. The return into water was one of the first important steps within turtle evolution making them a group of special interest. We are interested in the change from fully aquatic to fully terrestrial feeding modes that in some cases is genus-specific (intrafamiliar, e.g. within the south-east Asian Cuora species), in others an ontogenetic drift can be observed (e.g. in Heosemys grandis) – juveniles prefer to feed in water whereas adults prefer to stay and feed on land.

Recently, we started research with squamates feeding systems, especially with respect to their cranial kinesis. Cranial kinesis refers to intracranial movements in the vertebrate skull that do not concern the jaw joint, middle ear, or hyobranchial skeleton (i.e. mesokinesis, metakinesis, streptostyly). Cranial kinesis is widespread among vertebrates (fish, lizards, birds) and many theories about purpose and benefit arose. Again, we are highly interested in the evolution of this feature within the squamates.

A further project deals with different kinds of locomotion (snakelike, just forefeet, usage of all extremities) of a miniaturized snakelike skink, which is done in cooperation with Vladislav Vergilov.

We use on the one hand high-speed cinematography to describe feeding kinematics and on the other hand µCT stacks for segmentation of the necessary muscular features.

Ongoing projects:

> Skulls in motion: comparative study of cranial kinesis in lizards
> Dorsal tongue morphology in Cuora - evolution under the pressure of physical constraints? (Beisser & Blüml)
> Locomotion in Ablepharus kitaibelii (Lemell & Vergilov)

Recently completed:

> Feeding kinematics and skull morphology of the keeled box turtle Cuora mouhotii (Gray, 1862) (Valentin Blüml)
> Cranial kinesis in the miniaturised lizard Ablepharus kitaibelii (Handschuh et al.)
> Nahrungsaufnahme bei Shinisaurus crocodilurus (Ahl, 1930) (Rayno Tchobanov; in cooperation with Doris Nagel [Department of Palaeontology])

Feeding in mammals

Mastication is a fundamental activity undertaken by mammals and the extent of oral food processing distinguishes them from other vertebrate groups. In order to break down food effectively, mammals have evolved a complex set of masticatory muscles. The relative proportions of these muscles vary amongst mammals in a manner related to their diet and mode of feeding. The masticatory musculature of rodents represents an extreme version of the herbivore jaw-closing musculature configuration.

In cooperation with Doris Nagel (Department of Palaeontology), the morphology of the skull together with the feeding kinematics are examined in selected species.

Ongoing projects:

> Feeding in the darkness – intraspecific variations of the jaw mechanics in the naked mole-rat Heterocephalus glaber (Anastasia Kotlubei)
> Feeding in Tenrek (Staubmann; in cooperation with Doris Nagel [Department of Palaeontology]

Recently completed:

> Nahrungsaufnahme bei Cavia porcellus (Linnaeus, 1758). Ein Vergleich zwischen harter und weicher Nahrung (Anja Paster, in cooperation with Nagel [Department of Palaeontology])