Abstracts - Deutsche Zoologische Gesellschaft

Neurobiology Symposium 77O NB.5 (Su) - ENBee vision and flower detection: new insights from immunocytochemical andpsychophysical studiesJohannes SpaetheDepartment für Evolutionsbiologie, Universität Wien, ÖsterreichA major task of the visual system of bees is the detection of flowers during foraging flights. Detectionis determined by the size and shape of a flower, as well as its chromatic and achromatic contrastagainst the foliage. When searching for flowers, bees can optionally use a chromatic or achromaticvisual channel which differ in spatial resolution and receptor types involved. Immunocytochemicalstudies show that photoreceptors are heterogeneously expressed in the bee’s eye giving rise tothree ommatidial types in the main retina of which only one type comprises all three photoreceptors(UV, blue and green). Interestingly, the heterogeneity of the receptor distribution correlates with thespatial resolution of the different visual channels. However, flower detection is not only limited byoptical features of the flower but also by the complexity of the visual surrounding. When bees weretrained to choose a rewarding target among various non-rewarding distractors, search efficiency wassignificantly affected by the number and spectral quality of the distractors, indicating that flowerdetection is not simply a threshold problem.O NB.6 (Su) - ENThe infrared sensory organ in the Fossorial Python Aspidites sp.Guido Westhoff 1 , Shaun Collin 21Institute of Zoology, University of Bonn; 2 School of Biomedical Sciences, University of Queensland,AustraliaThe infrared sensitive organs of pythons are comprised of infrared sensitive thermoreceptors, whichare embedded within specialised pits of the labial scales. Infrared signals are detected by these pitslined with thermoreceptors, which project to the cns via the trigeminal nerve and a specialised nucleuswithin the hindbrain (nucleus of the lateral descending trigeminal tract: nLTTD). The nLTTDis only found in infrared sensitive snakes. The lack of labial pits and thus the obvious lack of theinfrared sense in Aspidites have been interpreted in the past as a primitive character of this genus oras a secondary loss. We investigated a conspicuous U-shaped single pit located in the rostralia of Aspiditessp. Scanning electron microscopy (SEM) has confirmed that the ultrastructure of the fundusof the pit resembles the fundus of labial pits in other pythons i.e. it possesses enlarged shingle likecells with micropits. Transmission electron microscopy (TEM) also reveals the presence of typicalinfrared thermoreceptors within the pit that are not found in other scales. Furthermore, a comparativemorphological analysis of the brain of Aspidites melanocephalus reveals a structure that can beregarded as a nLTTD. We propose that Aspidites clearly possesses an infrared sense and the unusualposition of the single, downwardly-directed pit in the rostralia has evolved in response to its fossoriallifestyle i.e. to avoid damage to the pit from soil and debris.