Main Areas of Research

List of publications by
Hans Schneider

List of publications
by coworkers



The Poppelsdorfer Schloss in Bonn is home
to the Institute for Zoology.

Hans Schneider and the
Institute for Zoology in Bonn.

Main Areas of Research

  1. One aspect emphasized by my studies was analysis of the various call types, primarily the advertisement calls; beginning with anurans native to Germany, the project was then extended to many species in other regions of Europe and beyond.
  2. Because anurans are ectothermic, many of their bodily functions are influenced by the ambient temperature, including the calls. Hence one objective was to determine the extent to which important characteristics of the mating calls and other call types are correlated with the temperature. Knowledge of these changes is indispensable in order to draw conclusions about the species-specificity of the advertisement calls. Furthermore, it is a crucial prerequisite for comparing the calls of the different species.
  3. Whereas the behaviour of other animal groups, for instance the birds, has long been the subject of intensive research, until very recently the behaviour of native anurans had attracted no appreciable interest. But the anurans have proved to be distinguished by diverse and specific behavioural traits that mainly determine their calling and reproductive behaviour. Hence another point of emphasis was to clarify these traits, e.g. by monitoring the daily and seasonal variations in the calls of male frogs and demonstrating the precise responses of the females to conspecific and simulated mating calls.
  4. Comparative morphological investigations revealed the structure of the larynx, the vocal cords and the laryngeal muscles, as well as other muscles involved in call production. Electron microscopic and experimental studies clarified the fine structure and the physiological properties of the laryngeal musculature.
  5. Physiological analyses provided information about the arrangement of the rest of the vocal system, the nerve centres involved in calling and the interaction of various neural structures during call production.
  6. Because the advertisement calls are extremely specific characteristics of a species, they constitute a valuable criterion for establishing the kinship relations among various anurans. Bioacoustic comparisons proved successful in tree frogs and water frogs, and resulted in a reorganization of anuran systematics, including the discovery of new species.
  7. At a later stage in the bioacoustic studies the anuran auditory organs were also included, as well as the sense organs in the labyrinth that mediate perception of gravity and movements. Comparative anatomical experiments provided information about the structure of the labyrinth in many anuran species, as well as the number and arrangement of the sensory cells at the sensory end points.
  8. The fine structure of the sensory cells themselves and the nature of stimulus transmission were an additional point of emphasis, as well as the development of the labyrinth and the differentiation of the sensory epitheliums during embryonic and larval development.
  9. Physiological studies in several native anuran species taught us about the neuronal auditory threshold curves and how they change under the influence of temperature.